Interface Configuration Guide Cisco IOS Realease 15M&T.html

Configuring Serial Interfaces

Last Updated: February 3, 2010

This module describes the procedure to configure serial interfaces. For hardware technical descriptions and information about installing interfaces, refer to the hardware installation and configuration publication for your product.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring Serial Interfaces" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.

Contents

•Prerequisites for Configuring Serial Interfaces

•Restrictions for Configuring Serial Interfaces

•Information About Configuring Serial Interfaces

•How to Configure Serial Interfaces

•Troubleshooting Serial Interfaces

•Configuration Examples for Serial Interface Configuration

•Additional References

•Feature Information for Configuring Serial Interfaces

Prerequisites for Configuring Serial Interfaces

The following are the prerequisites for configuring serial interfaces:

•Your hardware must support T3/E3 controllers and serial interfaces. The following hardware supports T3/E3 controllers and serial interfaces:

–2-Port and 4-Port Clear Channel T3/E3 SPAs

–2-Port and 4-Port Channelized T3 SPAs

•You have already configured the clear channel T3/E3 controller or channelized T3-to-T1/E1controller that is associated with the serial interface you want to configure.

Restrictions for Configuring Serial Interfaces

In case of auto installation over a serial interface using either HDLC or Frame Relay, it can be performed only over the first serial port on a new device (serial interface 0 or serial interface x/0).

Information About Configuring Serial Interfaces

To configure serial interfaces, you must understand the following concepts:

•Cisco HDLC Encapsulation

•PPP Encapsulation

•Keepalive Timer

•Layer 2 Tunnel Protocol Version 3-Based Layer 2 VPN on Frame Relay

•High-Speed Serial Interfaces

Cisco HDLC Encapsulation

Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for sending data over synchronous serial links using HDLC. Cisco HDLC also provides a simple control protocol called Serial Line Address Resolution Protocol (SLARP) to maintain serial link keepalives. Cisco HDLC is the default for data encapsulation at Layer 2 (data link) of the Open System Interconnection (OSI) stack for efficient packet delineation and error control.

Note Cisco HDLC is the default encapsulation type for the serial interfaces.

When the encapsulation on a serial interface is changed from HDLC to any other encapsulation type, the configured serial subinterfaces on the main interface inherit the newly changed encapsulation and they do not get deleted.

Cisco HDLC uses keepalives to monitor the link state, as described in the "Keepalive Timer" section.

PPP Encapsulation

PPP is a standard protocol used to send data over synchronous serial links. PPP also provides a Link Control Protocol (LCP) for negotiating properties of the link. LCP uses echo requests and responses to monitor the continuing availability of the link.

Note When an interface is configured with PPP encapsulation, a link is declared down, and full LCP negotiation is re-initiated after five ECHOREQ packets are sent without receiving an ECHOREP response.

PPP provides the following Network Control Protocols (NCPs) for negotiating properties of data protocols that will run on the link:

•IP Control Protocol (IPCP) to negotiate IP properties

•Multiprotocol Label Switching control processor (MPLSCP) to negotiate MPLS properties

•Cisco Discovery Protocol control processor (CDPCP) to negotiate CDP properties

•IPv6CP to negotiate IP Version 6 (IPv6) properties

•Open Systems Interconnection control processor (OSICP) to negotiate OSI properties

PPP uses keepalives to monitor the link state, as described in the "Keepalive Timer" section.

PPP supports the following authentication protocols, which require a remote device to prove its identity before allowing data traffic to flow over a connection:

•Challenge Handshake Authentication Protocol (CHAP)—CHAP authentication sends a challenge message to the remote device. The remote device encrypts the challenge value with a shared secret and returns the encrypted value and its name to the local router in a response message. The local router attempts to match the remote device's name with an associated secret stored in the local username or remote security server database; it uses the stored secret to encrypt the original challenge and verify that the encrypted values match.

•Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)—MS-CHAP is the Microsoft version of CHAP. Like the standard version of CHAP, MS-CHAP is used for PPP authentication; in this case, authentication occurs between a personal computer using Microsoft Windows NT or Microsoft Windows 95 and a Cisco router or access server acting as a network access server.

•Password Authentication Protocol (PAP)—PAP authentication requires the remote device to send a name and a password, which are checked against a matching entry in the local username database or in the remote security server database.

Use the ppp authentication command in interface configuration mode to enable CHAP, MS-CHAP, and PAP on a serial interface.

Note Enabling or disabling PPP authentication does not effect the local router's willingness to authenticate itself to the remote device.

Multilink PPP

Multilink Point-to-Point Protocol (MLPPP) is supported on the 1-Port Channelized OC-12/DS0 SPAs. MLPPP provides a method for combining multiple physical links into one logical link. The implementation of MLPPP combines multiple PPP serial interfaces into one multilink interface. MLPPP performs the fragmenting, reassembling, and sequencing of datagrams across multiple PPP links. MLPPP is supported on the 2-Port and 4-Port Channelized T3 SPAs.

MLPPP provides the same features that are supported on PPP Serial interfaces with the exception of QoS. It also provides the following additional features:

•Fragment sizes of 128, 256, and 512 bytes

•Long sequence numbers (24-bit)

•Lost fragment detection timeout period of 80 ms

•Minimum-active-links configuration option

•LCP echo request/reply support over multilink interface

•Full T1 and E1 framed and unframed links

Keepalive Timer

Cisco keepalives are useful for monitoring the link state. Periodic keepalives are sent to and received from the peer at a frequency determined by the value of the keepalive timer. If an acceptable keepalive response is not received from the peer, the link makes the transition to the down state. As soon as an acceptable keepalive response is obtained from the peer or if keepalives are disabled, the link makes the transition to the up state.

Note The keepalive command applies to serial interfaces using HDLC or PPP encapsulation. It does not apply to serial interfaces using Frame Relay encapsulation.

For each encapsulation type, a certain number of keepalives ignored by a peer triggers the serial interface to transition to the down state. For HDLC encapsulation, three ignored keepalives causes the interface to be brought down. For PPP encapsulation, five ignored keepalives causes the interface to be brought down. ECHOREQ packets are sent out only when LCP negotiation is complete (for example, when LCP is open).

Use the keepalive command in interface configuration mode to set the frequency at which LCP sends ECHOREQ packets to its peer. To restore the system to the default keepalive interval of 10 seconds, use the keepalive command with no argument. To disable keepalives, use the keepalive disable command. For both PPP and Cisco HDLC, a keepalive of 0 disables keepalives and is reported in the show running-config command output as keepalive disable.

When LCP is running on the peer and receives an ECHOREQ packet, it responds with an echo reply (ECHOREP) packet, regardless of whether keepalives are enabled on the peer.

Keepalives are independent between the two peers. One peer end can have keepalives enabled; the other end can have them disabled. Even if keepalives are disabled locally, LCP still responds with ECHOREP packets to the ECHOREQ packets it receives. Similarly, LCP also works if the period of keepalives at each end is different.

Frame Relay Encapsulation

When Frame Relay encapsulation is enabled on a serial interface, the interface configuration is hierarchical and comprises the following elements:

•The serial main interface comprises the physical interface and port. If you are not using the serial interface to support Cisco HDLC and PPP encapsulated connections, then you must configure subinterfaces with permanent virtual circuits (PVCs) under the serial main interface. Frame Relay connections are supported on PVCs only.

•Serial subinterfaces are configured under the serial main interface. A serial subinterface does not actively carry traffic until you configure a PVC under the serial subinterface. Layer 3 configuration typically takes place on the subinterface.

•When the encapsulation on a serial interface is changed from HDLC to any other encapsulation type, the configured serial subinterfaces on the main interface inherit the newly changed encapsulation and they do not get deleted.

•Point-to-point PVCs are configured under a serial subinterface. You cannot configure a PVC directly under a main interface. A single point-to-point PVC is allowed per subinterface. PVCs use a predefined circuit path and fail if the path is interrupted. PVCs remain active until the circuit is removed from either configuration. Connections on the serial PVC support Frame Relay encapsulation only.

Note The administrative state of a parent interface drives the state of the subinterface and its PVC. When the administrative state of a parent interface or subinterface changes, so does the administrative state of any child PVC configured under that parent interface or subinterface.

To configure Frame Relay encapsulation on serial interfaces, use the encapsulation (Frame Relay VC-bundle) command.

Frame Relay interfaces support two types of encapsulated frames:

•Cisco (default)

•IETF

Use the encap command in PVC configuration mode to configure Cisco or IETF encapsulation on a PVC. If the encapsulation type is not configured explicitly for a PVC, then that PVC inherits the encapsulation type from the main serial interface.

Note Cisco encapsulation is required on serial main interfaces that are configured for MPLS. IETF encapsulation is not supported for MPLS.

Before you configure Frame Relay encapsulation on an interface, you must verify that all prior
Layer 3 configuration is removed from that interface. For example, you must ensure that there is no IP address configured directly under the main interface; otherwise, any Frame Relay configuration done under the main interface will not be viable.

LMI on Frame Relay Interfaces

The Local Management Interface (LMI) protocol monitors the addition, deletion, and status of PVCs. LMI also verifies the integrity of the link that forms a Frame Relay UNI interface. By default, cisco LMI is enabled on all PVCs.

If the LMI type is cisco (the default LMI type), the maximum number of PVCs that can be supported under a single interface is related to the MTU size of the main interface. Use the following formula to calculate the maximum number of PVCs supported on a card or SPA:

(MTU - 13)/8 = maximum number of PVCs

Note The default setting of the mtu command for a serial interface is 1504 bytes. Therefore, the default numbers of PVCs supported on a serial interface configured with cisco LMI is 186.

Layer 2 Tunnel Protocol Version 3-Based Layer 2 VPN on Frame Relay

The Layer 2 Tunnel Protocol Version 3 (L2TPv3) feature defines the L2TP protocol for tunneling Layer 2 payloads over an IP core network using Layer 2 virtual private networks (VPNs).

L2TPv3 is a tunneling protocol used for transporting Layer 2 protocols. It can operate in a number of different configurations and tunnel a number of different Layer 2 protocols and connections over a packet-switched network.

Before you can configure L2TPv3, you need configure a connection between the two attachment circuits (ACs) that will host the L2TPv3 psuedowire. This module describes how to configure a Layer 2 AC on a Frame Relay encapsulated serial interface.

Note Serial interfaces support DLCI mode layer 2 ACs only; layer 2 port mode ACs are not supported on serial interfaces.

For detailed information about configuring L2TPv3 in your network, see the Cisco IOS Multiprotocol Label Switching Configuration Guide. For detailed information about configuring L2VPNs, see the L2VPN Interworking chapter in the Cisco IOS Multiprotocol Label Switching Configuration Guide.

High-Speed Serial Interfaces

The High-Speed Serial Interface (HSSI) Interface Processor (HIP) provides a single HSSI network interface. The network interface resides on a modular interface processor that provides a direct connection between the high-speed CiscoBus and an external network.

The HSSI port adapters (PA-H and PA-2H) are available on:

•Cisco 7200 series routers

•Second-generation Versatile Interface Processors (VIP2s) in Cisco 7500 series routers

•Cisco 7000 series routers with the 7000 series Route Switch Processor (RSP7000) and 7000 series Chassis Interface (RSP7000CI)

The PA-H provides one high-speed synchronous serial interface, and the PA-2H provides two high-speed synchronous serial interfaces that support full-duplex and data rates up to 52 Mbps. For more information on the PA-H, refer to the PA-H HSSI Port Adapter Installation and Configuration publication. For more information on the PA-2H, refer to the PA-2H Dual-Port HSSI Port Adapter Installation and Configuration publication.

The Cisco 3600 series 1-port HSSI network module provides full-duplex connectivity at SONET OC-1/STS-1 (51.840 MHz), T3 (44.736 MHz), and E3 (34.368 MHz) rates in conformance with the EIA/TIA-612 and EIA/TIA-613 specifications. The actual rate of the interface depends on the external data service unit (DSU) and the type of service to which it is connected. This 1-port HSSI network module can reach speeds of up to 52 Mbps in unidirectional traffic with 1548-byte packets and 4250 packets per second. ATM, High-Level Data Link Control (HDLC), PPP, Frame Relay, and Switched Multimegabit Data Service (SMDS) WAN services are all fully supported.

Before you configure the 1-port HSSI network module, complete the following prerequisite tasks:

•Install the HSSI Network Module in a chassis slot. For information on how to install this network module, refer to the "Installing a 1-Port HSSI Network Module in a Chassis Slot" section in the 1-Port HSSI Network Module Configuration Note publication.

•Complete basic device configuration, including host name, user name, protocol, and security configuration. For more information about basic device configuration, refer to the Cisco 3620 Installation and Configuration Guide or the Cisco 3640 Installation and Configuration Guide.

How to Configure Serial Interfaces

This section contains the following tasks:

•Configuring a High-Speed Serial Interface

•Configuring a Synchronous Serial Interface

•Configuring a Channelized T3 Interface Processor

•Configuring PA-E3 and PA-2E3 Serial Port Adapters

•Configuring PA-T3 and PA-2T3 Serial Port Adapters

•Configuring a Packet OC-3 Interface

•Configuring a DPT OC-12c Interface

•Configuring Automatic Protection Switching of Packet-over-SONET Circuits

•Configuring Serial Interfaces for CSU/DSU Service Modules

•Configuring Low-Speed Serial Interfaces

•Automatic Removal of tftp/ftp/rcp Source Interfaces Configuration

Configuring a High-Speed Serial Interface

To configure a High-speed serial interface (HSSI), perform the tasks in the following sections. Each task is identified as either required or optional.

•Specifying a HSSI Interface (Required)

•Specifying HSSI Encapsulation (Optional)

•Invoking ATM on a HSSI Line (Optional)

•Converting HSSI to Clock Master (Optional)

Specifying a HSSI Interface

To specify a High-Speed Serial Interface (HSSI) and enter interface configuration mode, use one of the following commands in global configuration mode.

Specifying HSSI Encapsulation

The HSSI supports the serial encapsulation methods, except for X.25-based encapsulations. The default method is HDLC. To define the encapsulation method, use the following command in interface configuration mode.

For information about PPP, refer to the "Configuring Asynchronous SLIP and PPP" and "Configuring Media-Independent PPP and Multilink PPP" chapters in the Cisco IOS Dial Technologies Configuration Guide.

Invoking ATM on a HSSI Line

If you have an ATM DSU, you can invoke ATM over a HSSI line. You do so by mapping an ATM virtual path identifier (VPI) and virtual channel identifier (VCI) to a Data Exchange Interface (DXI) frame address. ATM-DXI encapsulation defines a data exchange interface that allows a DTE (such as a router) and a DCE (such as an ATM DSU) to cooperate to provide a User-Network Interface (UNI) for ATM networks.

To invoke ATM over a serial line, use the following commands in interface configuration mode.

You can also configure the dxi map command on a serial interface.

To configure an ATM interface using an ATM Interface Processor (AIP) card, refer to the "Configuring ATM" chapter in the Cisco IOS Asynchronous Transfer Mode Configuration Guide.

Converting HSSI to Clock Master

The HSSI network module provides full-duplex connectivity at SONET OC-1/STS-1 (51.840 MHz), T3 (44.736 MHz), and E3 (34.368 MHz) rates in conformance with the EIA/TIA-612 and EIA/TIA-613 specifications. The actual rate of the interface depends on the DSU and the type of service to which it is connected. To convert the HSSI interface into a clock master use the following command in interface configuration mode.

Configuring a Synchronous Serial Interface

Synchronous serial interfaces are supported on various serial network interface cards or systems. These interfaces support full-duplex operation at T1 (1.544 Mbps) and E1 (2.048 Mbps) speeds. Refer to the Cisco Product Catalog for specific information regarding platform and hardware compatibility.

Synchronous Serial Configuration Task List

To configure a synchronous serial interface, perform the tasks in the following sections. Each task in the list is identified as either required or optional.

•Specifying a Synchronous Serial Interface (Required)

•Specifying Synchronous Serial Encapsulation (Optional)

•Configuring PPP (Optional)

•Configuring Half-Duplex and Bisync for Synchronous Serial Port Adapters on Cisco 7200 Series Routers (Optional)

•Configuring Compression Service Adapters on Cisco 7500 Series Routers (Optional)

•Configuring Compression of HDLC Data (Optional)

•Configuring Real-Time Transport Protocol Header Compression (Optional)

•Configuring the Data Compression AIM (Optional)

•Configuring the CRC (Optional)

•Using the NRZI Line-Coding Format (Optional)

•Enabling the Internal Clock (Optional)

•Inverting the Data (Optional)

•Inverting the Transmit Clock Signal (Optional)

•Setting Transmit Delay (Optional)

•Configuring DTR Signal Pulsing (Optional)

•Ignoring DCD and Monitoring DSR as Line Up/Down Indicator (Optional)

•Specifying the Serial Network Interface Module Timing (Optional)

•Specifying G.703 and E1-G.703/G.704 Interface Options (Optional)

See the "Configuration Examples for Serial Interface Configuration" for examples of configuration tasks described in this chapter.

Specifying a Synchronous Serial Interface

To specify a synchronous serial interface and enter interface configuration mode, use one of the following commands in global configuration mode.

Specifying Synchronous Serial Encapsulation

By default, synchronous serial lines use the High-Level Data Link Control (HDLC) serial encapsulation method, which provides the synchronous framing and error detection functions of HDLC without windowing or retransmission. The synchronous serial interfaces support the following serial encapsulation methods:

•ATM-DXI

•HDLC

•Frame Relay

•PPP

•Synchronous Data Link Control (SDLC)

•SMDS

•Cisco Serial Tunnel (STUN)

•X.25-based encapsulations

To define the encapsulation method, use the following command in interface configuration mode.

Note You cannot use the physical-layer async command for frame-relay encapsulation.

Encapsulation methods are set according to the type of protocol or application you configure in the Cisco IOS software.

•ATM-DXI is described in the "Configuring the CRC" section.

•PPP is described in the "Configuring Media-Independent PPP and Multilink PPP" chapter in the Cisco IOS Dial Technologies Configuration Guide.

•ATM, Frame Relay, and X.25 information and configuration steps are described in the Cisco IOS Asynchronous Transfer Mode Configuration Guide and the Cisco IOS Wide-Area Networking Configuration Guide.

•The remaining encapsulation methods are defined in their respective books and chapters describing the protocols or applications. Serial encapsulation methods are also discussed in the Cisco IOS Interface and Hardware Component Command Reference, under the encapsulation command.

By default, synchronous interfaces operate in full-duplex mode. To configure an SDLC interface for half-duplex mode, use the following command in interface configuration mode.

Binary synchronous communication (Bisync) is a half-duplex protocol. Each block of transmission is acknowledged explicitly. To avoid the problem associated with simultaneous transmission, there is an implicit role of primary and secondary station. The primary sends the last block again if there is no response from the secondary within the period of block receive timeout.

To configure the serial interface for full-duplex mode, use the following command in interface configuration mode.

Configuring PPP

To configure PPP, refer to the "Configuring Media-Independent PPP and Multilink PPP" chapter in the Cisco IOS Dial Technologies Configuration Guide.

Configuring Half-Duplex and Bisync for Synchronous Serial Port Adapters on Cisco 7200 Series Routers

The synchronous serial port adapters (PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+) on Cisco 7200 series routers support half-duplex and Bisync. Bisync is a character-oriented data-link layer protocol for half-duplex applications. In half-duplex mode, data is sent one direction at a time. Direction is controlled by handshaking the Request to Send (RST) and Clear to Send (CTS) control lines. These are described in the following sections:

•Configuring Bisync

•Changing Between Controlled-Carrier and Constant-Carrier Modes

For more information about the PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+ synchronous serial port adapters, refer to the following publications:

•PA-8T-V35 Synchronous Serial Port Adapter Installation and Configuration

•PA-8T-X21 Synchronous Serial Port Adapter Installation and Configuration

•PA-8T-232 Synchronous Serial Port Adapter Installation and Configuration

•PA-4T+ Synchronous Serial Port Adapter Installation and Configuration

Configuring Bisync

To configure the Bisync feature on the synchronous serial port adapters (PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+) on Cisco 7200 series routers, refer to the "Block Serial Tunnelling (BSTUN)" section of the "Configuring Serial Tunnel and Block Serial Tunnel" chapter of the Cisco IOS Bridging and IBM Networking Configuration Guide. All commands listed in the "Block Serial Tunnelling (BSTUN) Overview" section apply to the synchronous serial port adapters on Cisco 7200 series routers. Any command syntax that specifies an interface number supports the Cisco 7200 series slot/port syntax.

•Changing Between Controlled-Carrier and Constant-Carrier Modes

Configuring Compression Service Adapters on Cisco 7500 Series Routers

The SA-Comp/1 and SA-Comp/4 data compression service adapters (CSAs) are available on:

•Cisco 7200 series routers

•Second-generation Versatile Interface Processors (VIP2s) in Cisco 7500 series routers (CSAs require VIP2 model VIP2-40.)

The SA-Comp/1 supports up to 64 WAN interfaces, and the SA-Comp/4 supports up to 256 WAN interfaces.

On the Cisco 7200 series routers you can optionally specify which CSA the interface uses to perform hardware compression.

You can configure point-to-point compression on serial interfaces that use PPP encapsulation. Compression reduces the size of a PPP frame via lossless data compression. PPP encapsulations support both predictor and Stacker compression algorithms.

Note If the majority of your traffic is already compressed files, do not use compression.

When you configure Stacker compression on Cisco 7200 series routers and on Cisco 7500 series routers, there are three methods of compression: hardware compression, distributed compression, and software compression. Specifying the compress stac command with no options causes the router to use the fastest available compression method, as described here:

•If the router contains a compression service adapter (CSA), compression is performed in the CSA hardware (hardware compression).

•If the CSA is not available, compression is performed in the software installed on the VIP2 (distributed compression).

•If the VIP2 is not available, compression is performed in the router's main processor (software compression).

Using hardware compression in the CSA frees the main processor of the router for other tasks. You can also configure the router to use the VIP2 to perform compression by using the distributed option on the compress command, or to use the main processor of the router by using the software option on the compress command. If the VIP2 is not available, compression is performed in the main processor of the router.

When compression is performed in software installed in the main processor of the router, it might significantly affect system performance. You should disable compression in the router's main processor if the router CPU load exceeds 40 percent. To display the CPU load, use the show process cpu EXEC command.

For instructions on configuring compression over PPP, refer to the "Configuring Media-Independent PPP and Multilink PPP" chapter in the Cisco IOS Dial Technologies Configuration Guide.

Configuring Compression of HDLC Data

You can configure point-to-point software compression on serial interfaces that use HDLC encapsulation. Compression reduces the size of a HDLC frame via lossless data compression. The compression algorithm used is a Stacker (LZS) algorithm.

Compression is performed in software and might significantly affect system performance. We recommend that you disable compression if CPU load exceeds 65 percent. To display the CPU load, use the show process cpu EXEC command.

If the majority of your traffic is already compressed files, you should not use compression.

To configure compression over HDLC, use the following commands in interface configuration mode.

Configuring Real-Time Transport Protocol Header Compression

Real-time Transport Protocol (RTP) is a protocol used for carrying packetized audio and video traffic over an IP network. RTP is described in RFC 1889, RTP—A Transport Protocol for Real-Time Applications. RTP is not intended for data traffic, which uses TCP or UDP (User Datagram Protocol). RTP provides end-to-end network transport functions intended for applications with real-time requirements, such as audio, video, or simulation data over multicast or unicast network services.

For information and instructions for configuring RTP header compression, refer to the Cisco IOS IP Multicast Configuration Guide.

Configuring the Data Compression AIM

The data compression Advanced Interface Module (AIM) provides hardware-based compression and decompression of packet data transmitted and received on the serial network interfaces of the Cisco 2600 series router without occupying the Port Module Slot which might otherwise be used for additional customer network ports. Supported are the industry standard Lempel-Ziv Stac (LZS) and Microsoft point-to-point compression (MPPC) compression algorithms over point-to-point protocol (PPP) or Frame Relay. High-level Data Link Control (HDLC) is not supported. The data compression AIM requires Cisco IOS Release 12.0(1)T or later.

The data compression AIM is a daughtercard assembly that attaches directly to the Cisco 2600 motherboard leaving the single network module slot available for other purposes. The data compression AIM supports only serial interfaces using PPP encapsulation with STAC or MPPC compression, or Frame Relay encapsulation with STAC compression. No routing, bridging, or switching performance is impacted by this feature. The data compression AIM module contains a high-performance data compression coprocessor that implements the LZS and MPPC data compression algorithms. The module provides compression support for up to two E1 lines. The module contains a PCI Target/Initiator system bus interface for access into host system memory with minimal Host processor intervention.

To configure the data compression AIM daughtercard assembly, perform the following tasks:

•Configuring PPP Compression

•Configuring Frame Relay Map Compression

•Configuring Frame Relay Payload Compression

•Configuring Diagnostics

Configuring PPP Compression

Configure your Cisco 2600 access server to use PPP compression. Specify the following information for each serial interface:

•encapsulation type

•compression algorithm

•the CAIM daughtercard to be designated as the source of this algorithm, and the port.

To configure the PPP form of compression, use the following commands, beginning in privileged EXEC mode.

Verifying PPP Compression

To check that the interface is activated, use the show interfaces serial slot/port command. Notice the highlighted fields in the following example:

Router# show interfaces serial 0/0

Serial0/0 is up, line protocol is up

  Hardware is PowerQUICC Serial

  Internet address is 1.1.1.2/24

  MTU 1500 bytes, BW 2000 Kbit, DLY 20000 usec,

     reliability 255/255, txload 3/255, rxload 50/255

  Encapsulation PPP, loopback not set, keepalive not set

  LCP Open

  Open: IPCP, CCP ==> If two routers have successfully negotiated compression.

  Last input 00:00:04, output 00:00:00, output hang never

  Last clearing of "show interface" counters 1w1d

  Queueing strategy: fifo

  Output queue 0/40, 80 drops; input queue 0/75, 0 drops

  30 second input rate 397000 bits/sec, 40 packets/sec

  30 second output rate 30000 bits/sec, 40 packets/sec

     27859655 packets input, 4176659739 bytes, 0 no buffer

     Received 175145 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

     55309592 packets output, 1044865717 bytes, 0 underruns

     0 output errors, 0 collisions, 12 interface resets

     0 output buffer failures, 0 output buffers swapped out

     36 carrier transitions

     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

To indicate whether compression is active, use the show compress command. Notice the highlighted fields in the following example:

Router# show compress

 Serial0/0

     Hardware compression enabled

     CSA in slot 0 in use

     Compressed bytes sent:  317862131 bytes   61 Kbits/sec  ratio: 12.870

     Compressed bytes recv:  221975672 bytes   43 Kbits/sec  ratio: 9.194

     restarts: 1

     last clearing of counters: 41252 seconds

Tip•The interface must report being up.

•No errors should be reported.

•Check this interface again after you are sure that traffic is getting to the Cisco 2600 series router and verify that the Compressed bytes recv field value changes.

Configuring Frame Relay Map Compression

Configure Frame Relay to map compression on this Data-Link Connection Identifier (DLCI) to use the specified AIM hardware compression on the Cisco 2600 access server. You must specify the following information for each serial interface:

•The protocol, protocol address

•DLCI

•Encapsulation type

•FRF.9 stac compression algorithm

You must also designate the CAIM daughtercard as a source of this algorithm, and the CAIM element number.

To configure the Frame Relay map compression command for operation, use the following commands beginning in privileged EXEC mode.

Note The compress ppp command applied to the PPP compression configuration example above has no equivalent for compression under Frame Relay.

Verifying Frame Relay Map Compression

To check that the interface is activated with proper compression and encapsulation, use the show interfaces serial slot/port command. Notice the highlighted fields in the following example:

Router# show interfaces serial 0/1

Serial0/1 is up, line protocol is up

  Hardware is PowerQUICC Serial

  Internet address is 1.1.1.2/24

  MTU 1500 bytes, BW 2000 Kbit, DLY 20000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation FRAME-RELAY, loopback not set, keepalive not set

  FR SVC disabled, LAPF state down

  Broadcast queue 0/64, broadcasts sent/dropped 2743/0, interface broadcasts 2742

  Last input 03:05:57, output 00:00:03, output hang never

  Last clearing of "show interface" counters 1w1d

  Queueing strategy: fifo

  Output queue 0/40, 80 drops; input queue 0/75, 0 drops

  30 second input rate 0 bits/sec, 0 packets/sec

  30 second output rate 0 bits/sec, 0 packets/sec

     30800054 packets input, 3488155802 bytes, 0 no buffer

     Received 199567 broadcasts, 0 runts, 0 giants, 0 throttles

     2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored, 0 abort

     58246738 packets output, 1325052697 bytes, 0 underruns

     0 output errors, 0 collisions, 15 interface resets

     0 output buffer failures, 0 output buffers swapped out

     36 carrier transitions

     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

To indicate whether compression is active, use the show controllers serial slot/port command. Notice the highlighted fields in the following example:

Router# show controllers serial 1/0

CD2430 Slot 1, Port 0, Controller 0, Channel 0, Revision 14

Channel mode is synchronous serial 

idb 0x811082E8, buffer size 1524, X.21 DTE cable

Global registers

  rpilr 0x2, rir 0x0, risr 0x0, rfoc 0x0, rdr 0x30

  tpilr 0x1, tir 0x0, tisr 0x60, tftc 0x0, tdr 0x41

  mpilr 0x3, mir 0x2, misr 0x60

  bercnt 0xFF, stk 0x0

Per-channel registers for channel 0

  Option registers

  0x02 0x00 0x42 0xE7 0xE0 0x00 0x00

  Command and status registers

  cmr 0xC0, ccr 0x00, csr 0xAC, msvr-rts 0xF1, msvr-dtr 0xF1

  Clock option registers

  rcor 0x06, rbpr 0x01, tcor 0xC8, tbpr 0x01

  Interrupt registers

  ier 0x89, livr 0x00, licr 0x00

  DMA buffer status 0x27

  DMA receive registers

  arbaddr 0x2549D44, arbcnt 1548, arbsts 0x1

  brbaddr 0x2548344, brbcnt 1548, brbsts 0x1

  rcbaddr 0x2549D94

  DMA transmit registers

  atbaddr 0x257F93E, atbcnt 104, atbsts 0x43

  btbaddr 0x25B25C2, btbcnt 1490, btbsts 0x43

  tcbaddr 0x25B25D2

  Special character registers

  schr1 0x00, schr2 0x00, schr3 0x00, schr4 0x00

  scrl 0x0, scrh 0x0, lnxt 0xF1

Driver context information

  Context structure 0x8110D830, Register table 0x40800400

  Serial Interface Control 5:1 Register (0x40800802) is 0x0

  Adaptor Flags 0x0

  Serial Modem Control Register (0x40800804) is 0x18

  Receive static buffer 0x810E1274

  Receive particle buffers 0x8110DE00, 0x8110DDC0

  Transmit DMA buffers 0x8113E240, 0x810F2808, 0x810D4C00, 0x810EA0DC

  Transmit packet with particles 0x0, first word is 0x0

  Interrupt rates (per second) transmit 25, receive 139, modem 0

  True fast-switched packets    41

  Semi fast-switched packets    13449573

  Transmitter hang count        0

  Residual indication count     0

  Bus error count       0

  Aborted short frames count    0

  CRC short frames count        0

Error counters

  CTS deassertion failures      0

  Nested interrupt errors transmit 0, receive 0, modem 0

Using Compression AIM 0

CompressionAim0

    ds:0x8113FC04 idb:0x8113A6CC

       5005867 uncomp paks in -->      5005867 comp paks out

      38397501 comp paks in   -->     38397502 uncomp paks out

    2882277146 uncomp bytes in-->    497476655 comp bytes out

    3500965085 comp bytes in  -->   1211331227 uncomp bytes out

            72 uncomp paks/sec in-->        72 comp paks/sec out

           557 comp paks/sec in  -->       557 uncomp paks/sec out

        334959 uncomp bits/sec in-->     57812 comp bits/sec out

        406855 comp bits/sec in  -->    140827 uncomp bits/sec out

    68841 seconds since last clear

    holdq:0  hw_enable:1  src_limited:0  num cnxts:8

    no data:0  drops:0  nobuffers:0  enc adj errs:0  fallbacks:

5322165

    no Replace:0  num seq errs:0  num desc errs:0  cmds complete:

43403738

    Bad reqs:0  Dead cnxts:0  No Paks:0  enq errs:0

    rx pkt drops:0  tx pkt drops:0  dequeues:0  requeues:0

    drops disabled:0  clears:0  ints:41973007  purges:203200

    no cnxts:0  bad algos:0  no crams:0  bad paks:0

    # opens:0  # closes:4  # hangs:0

    # 9711 fatal:0  # poison pkts:0  cmd/res ovruns:0

    # dma fatal:0

    Jupiter DMA Controller Registers:(0x40200000

        Cmd Ring:0x025BAE60  Src Ring:0x025BBB60

        Res Ring:0x025BB4E8  Dst Ring:0x025BBDA8

        Status/Cntl:present:0x8080989C  last int:0x9898989C

        Inten:0x30302021  config:0x00080003

        Num DMA ints:41973355

    Hifn9711 Data Compression Coprocessor Registers (0x40201000):

        Config:0x000051D4  Inten:0x00000E00

        Status:0x00004000  FIFO status:0x00004000

        FIFO config:0x00000101

Tip•The interface must report being up.

•No errors should be reported.

•Check this interface again after you are sure that traffic is getting to the Cisco 2600 series router and verify that the Compressed bytes recv field value changes.

Configuring Frame Relay Payload Compression

To configure Frame Relay payload compression, use the following commands beginning in privileged EXEC mode.

Verifying Frame Relay Payload Compression

To check that the interface is activated with proper compression and encapsulation, use the show interfaces serial slot/port command. Notice the highlighted fields in the following example:

Router# show interfaces serial 0/0

Serial0/0 is up, line protocol is up

  Hardware is PowerQUICC Serial

  Internet address is 1.1.1.2/24

  MTU 1500 bytes, BW 2000 Kbit, DLY 20000 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation FRAME-RELAY, loopback not set, keepalive not set

  FR SVC disabled, LAPF state down

  Broadcast queue 0/64, broadcasts sent/dropped 2743/0, interface broadcasts 2742

  Last input 03:05:57, output 00:00:03, output hang never

  Last clearing of "show interface" counters 1w1d

  Queueing strategy: fifo

  Output queue 0/40, 80 drops; input queue 0/75, 0 drops

  30 second input rate 0 bits/sec, 0 packets/sec

  30 second output rate 0 bits/sec, 0 packets/sec

     30800054 packets input, 3488155802 bytes, 0 no buffer

     Received 199567 broadcasts, 0 runts, 0 giants, 0 throttles

     2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored, 0 abort

     58246738 packets output, 1325052697 bytes, 0 underruns

     0 output errors, 0 collisions, 15 interface resets

     0 output buffer failures, 0 output buffers swapped out

     36 carrier transitions

     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

Note FRAME-RELAY is not displayed using the show compress command. Use the debug compress command to see this information.

Tip•The interface must report being up.

•No errors should be reported.

Configuring Diagnostics

Configure the AIM daughtercard to provide compression for the Cisco 2600 series router. You must specify the following information for each daughtercard installed.

To configure the PPP for compression, use the following commands beginning in user EXEC mode.

Verifying Diagnostics

To check that the data compression AIM is collecting statistics that represent proper compression, use the show pas caim stats element-number command:

Router# show pas caim stats 0

CompressionAim0

      ds:0x80F56A44 idb:0x80F50DB8

          422074 uncomp paks in -->       422076 comp paks out

          422071 comp paks in   -->       422075 uncomp paks out

       633912308 uncomp bytes in-->     22791798 comp bytes out

        27433911 comp bytes in  -->    633911762 uncomp bytes out

             974 uncomp paks/sec in-->       974 comp paks/sec out

             974 comp paks/sec in  -->       974 uncomp paks/sec out

        11739116 uncomp bits/sec in-->    422070 comp bits/sec out

          508035 comp bits/sec in  -->  11739106 uncomp bits/sec out

      433 seconds since last clear

      holdq: 0  hw_enable: 1  src_limited: 0  num cnxts: 4

      no data: 0  drops: 0  nobuffers: 0  enc adj errs: 0  fallbacks: 0

      no Replace: 0  num seq errs: 0  num desc errs: 0  cmds complete: 844151

      Bad reqs: 0  Dead cnxts: 0  No Paks: 0  enq errs: 0

      rx pkt drops: 0  tx pkt drops: 0  dequeues: 0  requeues: 0

      drops disabled: 0  clears: 0  ints: 844314  purges: 0

      no cnxts: 0  bad algos: 0  no crams: 0  bad paks: 0

      # opens: 0  # closes: 0 # hangs: 0

To identify compression characteristics for each port, use the show compress command:

Router# show compress

 Serial0/0

     Hardware compression enabled

     CSA in slot 0 in use

     Compressed bytes sent:  317862131 bytes   61 Kbits/sec  ratio: 12.870

     Compressed bytes recv:  221975672 bytes   43 Kbits/sec  ratio: 9.194

     restarts: 1

     last clearing of counters: 41252 seconds

 Serial0/1

     Hardware compression enabled

     CSA in slot 0 in use

     Compressed bytes sent:     249720 bytes    0 Kbits/sec  ratio: 5.923

     Compressed bytes recv:  465843659 bytes   43 Kbits/sec  ratio: 9.128

     restarts: 1

     last clearing of counters: 85525 seconds

To reset the CAIM hardware to 0, use the clear compress command. There is no output for this command; instead, check the output from the show compress command to verify the result:

Router# clear compress

Router# show compress

 Serial0/0

     Hardware compression enabled

     CSA in slot 0 in use

     Compressed bytes sent:  0 bytes   61 Kbits/sec  ratio: 0

     Compressed bytes recv:  0 bytes   43 Kbits/sec  ratio: 0

     restarts: 0

     last clearing of counters: 0 seconds

Tip•The interface must report being up.

•No errors should be reported.

Configuring the CRC

The cyclic redundancy check (CRC) on a serial interface defaults to a length of 16 bits. To change the length of the CRC to 32 bits on an Fast Serial Interface Processor (FSIP) or HSSI Interface Processor (HIP) of the Cisco 7500 series only, use the following command in interface configuration mode.

Using the NRZI Line-Coding Format

The nonreturn-to-zero (NRZ) and nonreturn-to-zero inverted (NRZI) formats are supported on:

•All FSIP interface types on Cisco 7500 series routers

•PA-8T and PA-4T+ synchronous serial port adapters on:

–Cisco 7000 series routers with RSP7000

–Cisco 7200 series routers

–Cisco 7500 series routers

NRZ and NRZI are line-coding formats that are required for serial connections in some environments. NRZ encoding is most common. NRZI encoding is used primarily with EIA/TIA-232 connections in IBM environments.

The default configuration for all serial interfaces is NRZ format. The default is no nrzi-encoding.

To enable NRZI format, use one of the following commands in interface configuration mode.

Enabling the Internal Clock

When a DTE does not return a transmit clock, use the following interface configuration command on the Cisco 7000 series to enable the internally generated clock on a serial interface:

Inverting the Data

If the interface on the PA-8T and PA-4T+ synchronous serial port adapters is used to drive a dedicated T1 line that does not have B8ZS encoding, you must invert the data stream on the connecting CSU/DSU or on the interface. Be careful not to invert data on both the CSU/DSU and the interface because two data inversions will cancel each other out.

If the T1 channel on the CT3IP is using alternate mark inversion (AMI) line coding, you must invert the data. For more information, refer to the t1 linecode controller configuration command. For more information on the CT3IP, see the "Configuring a Channelized T3 Interface Processor" section.

To invert the data stream, use the following command in interface configuration mode.

Inverting the Transmit Clock Signal

Systems that use long cables or cables that are not transmitting the TxC signal (transmit echoed clock line, also known as TXCE or SCTE clock) can experience high error rates when operating at the higher transmission speeds. For example, if the interface on the PA-8T and PA-4T+ synchronous serial port adapters is reporting a high number of error packets, a phase shift might be the problem. Inverting the clock signal can correct this shift. To invert the clock signal, use the following commands in interface configuration mode.

Setting Transmit Delay

It is possible to send back-to-back data packets over serial interfaces faster than some hosts can receive them. You can specify a minimum dead time after transmitting a packet to remove this condition. This setting is available for serial interfaces on the MCI and SCI interface cards and for the HSSI or MIP. Use one of the following commands, as appropriate for your system, in interface configuration mode.

Configuring DTR Signal Pulsing

You can configure pulsing dedicated Token Ring (DTR) signals on all serial interfaces. When the serial line protocol goes down (for example, because of loss of synchronization), the interface hardware is reset and the DTR signal is held inactive for at least the specified interval. This function is useful for handling encrypting or other similar devices that use the toggling of the DTR signal to reset synchronization. To configure DTR signal pulsing, use the following command in interface configuration mode.

Ignoring DCD and Monitoring DSR as Line Up/Down Indicator

This task applies to:

•Quad Serial NIM (network interface module) interfaces on the Cisco 4000 series

•Hitachi-based serial interfaces on the Cisco 2500 series and Cisco 3000 series

By default, when the serial interface is operating in DTE mode, it monitors the Data Carrier Detect (DCD) signal as the line up/down indicator. By default, the attached DCE device sends the DCD signal. When the DTE interface detects the DCD signal, it changes the state of the interface to up.

In some configurations, such as an SDLC multidrop environment, the DCE device sends the Data Set Ready (DSR) signal instead of the DCD signal, which prevents the interface from coming up. To tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator, use the following command in interface configuration mode.

Caution Unless you know for certain that you really need this feature, be very careful using this command. It will hide the real status of the interface. The interface could actually be down and you will not know by looking at show displays.

Specifying the Serial Network Interface Module Timing

On Cisco 4000 series routers, you can specify the serial Network Interface Module timing signal configuration. When the board is operating as a DCE and the DTE provides terminal timing (SCTE or TT), you can configure the DCE to use SCTE from the DTE. When running the line at high speeds and long distances, this strategy prevents phase shifting of the data with respect to the clock.

To configure the DCE to use SCTE from the DTE, use the following command in interface configuration mode.

When the board is operating as a DTE, you can invert the TXC clock signal it gets from the DCE that the DTE uses to transmit data. Invert the clock signal if the DCE cannot receive SCTE from the DTE, the data is running at high speeds, and the transmission line is long. Again, this prevents phase shifting of the data with respect to the clock.

To configure the interface so that the router inverts the TXC clock signal, use the following command in interface configuration mode.

Specifying G.703 and E1-G.703/G.704 Interface Options

This section describes the optional tasks for configuring a G.703 serial interface (a serial interface that meets the G.703 electrical and mechanical specifications and operates at E1 data rates). G.703 interfaces are available on port adapters for the Fast Serial Interface Processor (FSIP) on a Cisco 4000 series or Cisco 7500 series router.

The E1-G.703/G.704 serial port adapters (PA-4E1G-120 and PA-4E1G-75) are available on:

•Cisco 7500 series routers

•Cisco 7200 series routers

•Cisco 7000 series routers with the 7000 series Route Switch Processor (RSP7000) and 7000 series Chassis Interface (RSP7000CI)

These port adapters provide up to four E1 synchronous serial interfaces, which are compatible with and specified by G.703/G.704. The PA-4E1G-120 supports balanced operation, and the PA-4E1G-75 supports unbalanced operation with 15-pin, D-shell (DB-15) receptacles on the port adapters. Both port adapters operate in full-duplex mode at the E1 speed of 2.048 Mbps.

Configuration tasks are described in the following sections:

•Enabling Framed Mode

•Enabling CRC4 Generation

•Using Time Slot 16 for Data

•Specifying a Clock Source

Enabling Framed Mode

G.703 interfaces have two modes of operation: framed and unframed. By default, G.703 serial interfaces are configured for unframed mode. To enable framed mode, use the following command in interface configuration mode.

To restore the default, use the no form of this command or set the starting time slot to 0.

Enabling CRC4 Generation

By default, the G.703 CRC4, which is useful for checking data integrity while operating in framed mode, is not generated. To enable generation of the G.703 CRC4, use the following command in interface configuration mode.

Using Time Slot 16 for Data

By default, time slot 16 is used for signaling. It can also be used for data (in order to get all possible subframes or time slots when in framed mode). To specify the use of time slot 16 for data, use the following command in interface configuration mode.

Specifying a Clock Source

A G.703 interface can clock its transmitted data either from its internal clock or from a clock recovered from the receive data stream of the line. By default, the interface uses the receive data stream of the line. To control which clock is used, use the following command in interface configuration mode.

Configuring a Channelized T3 Interface Processor

The Channelized T3 Interface Processor (CT3IP) is available on:

•Cisco 7500 series routers

•Cisco 7000 series routers with the 7000 series Route Switch Processor (RSP7000) and 7000 series Chassis Interface (RSP7000CI)

The Channelized T3 (CT3) feature board is available on Cisco AS5800 access servers.

These cards provide for the aggregation of channelized interfaces into a single T3 facility. T3 support on the Cisco AS5800 allows support for 28 T1s (672 channels) per chassis. The Channelized T3 dual-wide port adapter (PA-CT3/4T1) can be used in Cisco 7200 series routers.

Note Throughout this document are references to the CT3IP. However, the term CT3IP also applies to the PA-CT3/4T1 and to the CT3 feature board. Wherever you see a description of a feature of the CT3IP, the feature is also available in the PA-CT3/4T1 and the CT3 feature board, unless otherwise indicated.

The CT3IP is a fixed-configuration interface processor based on the second-generation Versatile Interface Processor (VIP2). The CT3 channelized port adapter (PA-CT3/4T1) is a dual-wide port adapter. The CT3IP or PA-CT3/4T1 has four T1 connections via DB-15 connectors and one DS3 connection via BNC connectors. Each DS3 interface can provide up to 28 T1 channels (a single T3 group). Each channel is presented to the system as a serial interface that can be configured individually. The CT3IP or PA-CT3/4T1 can transmit and receive data bidirectionally at the T1 rate of 1.536 Mbps. The four T1 connections use 100-ohm twisted-pair serial cables to external channel service units (CSUs) or to a MultiChannel Interface Processor (MIP) on the same router or on another router. For wide-area networking, the CT3IP or PA-CT3/4T1 can function as a concentrator for a remote site.

Note The VIP2-50 is the newest and fastest second-generation Versatile Interface Processor (VIP2) available on Cisco 7500 series routers that use the Route Switch Processor (RSP), and on Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI). The VIP2-50 provides significantly greater packet and program memory space and increased distributed switching performance.

For more information on the VIP2-50, refer to the Second-Generation Versatile Interface Processor (VIP2) Installation, Configuration, and Maintenance publication.

As mentioned above, the CT3IP or PA-CT3/4T1 provides 28 T1 channels for serial transmission of data. Each T1 channel can be configured to use a portion of the T1 bandwidth or the entire T1 bandwidth for data transmission. Bandwidth for each T1 channel can be configured for n x 56 kbps or n x 64 kbps (where n is 1 to 24). The unused portion of the T1 bandwidth, when not running at full T1 speeds, is filled with idle channel data. The CT3IP or PA-CT3/4T1 does not support the aggregation of multiple T1 channels (called inverse muxing or bonding) for higher bandwidth data rates.

The first three T1 channels of the CT3IP or PA-CT3/4T1 can be broken out to the three DSUP-15 connectors on the CPT3IP or PA-CT3/4T1 so that the T1 can be further demultiplexed by the MIP on the same router or on another router or by other multiplexing equipment. When connecting to the MIP, you configure a channelized T1 as described in the "Configuring External T1 Channels" section. This is referred to as an external T1 channel.

The CT3IP supports RFC 1406, Definitions of Managed Objects for DS1 and E1 Interface Types, and RFC 1407, DS3 MIB Variables (CISCO-RFC-1407-CAPABILITY.my). For information about Cisco MIBs, refer to the current Cisco IOS release note for the location of the MIB online reference.

For RFC 1406, Cisco supports all tables except the "Frac" table. For RFC 1407, Cisco supports all tables except the "FarEnd" tables.

The CT3IP supports the following WAN protocols:

•Frame Relay

•HDLC

•PPP

•SMDS Data Exchange Interface (DXI)

The CT3IP meets ANSI T1.102-1987 and BELCORE TR-TSY-000499 specifications for T3 and meets ANSI 62411 and BELCORE TR499 specifications for T1. The CT3IP provides internal CSU functionality and includes reporting performance data statistics, transmit and receive statistics, and error statistics. The CT3IP supports RFC 1406 (T1 MIB) and RFC 1407 (T3 MIB).

External T1 channels do not provide CSU functionality and must connect to an external CSU.

Channelized T3 Configuration Task List

To configure the CT3IP, perform the tasks in the following sections. Each task is identified as either required or optional.

•Configuring T3 Controller Support for the Cisco AS5800 (Optional)

•Configuring the T3 Controller (Optional)

•Configuring Each T1 Channel (Required)

•Configuring External T1 Channels (Optional)

•Monitoring and Maintaining the CT3IP (Optional)

•Verifying T3 Configuration (Optional)

•Configuring Maintenance Data Link Messages (Optional)

•Enabling Performance Report Monitoring (Optional)

•Configuring for BERT on the Cisco AS5300 (Optional)

•Verifying BERT on the Cisco AS5300 (Optional)

•Enabling a BERT Test Pattern (Optional)

•Enabling Remote FDL Loopbacks (Optional)

•Configuring T1 Cable Length and T1/E1 Line Termination (Optional)

After you configure the T1 channels on the CT3IP, you can continue configuring it as you would a normal serial interface.

For CT3IP configuration examples, see the "Channelized T3 Interface Processor Configuration: Examples" section.

Configuring T3 Controller Support for the Cisco AS5800

To configure T3 controller support specifically for the CT3 feature board in a Cisco AS5800 access server, use the following commands beginning in user EXEC mode.

Configuring the T3 Controller

If you do not modify the configuration of the CT3IP, the configuration defaults shown in Table 1 are used.

If you must change any of the default configuration attributes, use the following commands beginning in global configuration mode.

Configuring Each T1 Channel

You must configure the time slots used by each T1 channel on the CT3IP. Optionally, you can specify the speed, framing format, and clock source used by each T1 channel. If you do not specify the speed, framing format, and clock source used by each T1 channel, the configuration defaults shown in Table 2 are used.

To specify the time slots used by each T1 channel, use the following commands beginning in global configuration mode.

Note The 56-kbps speed is valid only for T1 channels 21 through 28.

Note T1 channels on the CT3IP are numbered 1 to 28 rather than the more traditional zero-based scheme (0 to 27) used with other Cisco products. This numbering scheme is to ensure consistency with telco numbering schemes for T1 channels within channelized T3 equipment.

If you need to change any of the default configuration attributes, use the following commands, beginning in global configuration mode.

After you configure the T1 channels on the CT3IP, you can continue configuring it as you would a normal serial interface. All serial interface commands might not be applicable to the T1 channel. For more information, see the "Configuring a Synchronous Serial Interface" section.

To enter interface configuration mode and configure the serial interface that corresponds to a T1 channel, use the following command in global configuration mode.

In addition to the commands in the "Configuring a Synchronous Serial Interface" section, the invert data interface command can be used to configure the T1 channels on the CT3IP. If the T1 channel on the CT3IP is using AMI line coding, you must invert the data. For information on the invert data interface command, see the "Inverting the Data" section. For more information, refer to the t1 linecode controller configuration command in the Cisco IOS Interface and Hardware Component Command Reference.

Configuring External T1 Channels

The first three T1 channels (1, 2, and 3) of the CT3IP can be broken out to the DSUP-15 connectors so that the T1 channel can be further demultiplexed by the MIP on the same router, another router, or other multiplexing equipment.

Note If a T1 channel that was previously configured as a serial interface is broken out to the external T1 port, that interface and its associated configuration remain intact while the channel is broken out to the external T1 port. The serial interface is not usable during the time that the T1 channel is broken out to the external T1 port; however, the configuration remains to facilitate the return of the T1 channel to a serial interface using the no t1 external command.

To configure a T1 channel as an external port, use the following commands beginning in EXEC mode.

After you configure the external T1 channel, you can continue configuring it as a channelized T1 from the MIP. All channelized T1 commands might not be applicable to the T1 interface. To define the T1 controller and enter controller configuration mode, use the following command in global configuration mode.

After you configure the channelized T1 on the MIP, you can continue configuring it as you would a normal serial interface. All serial interface commands might not be applicable to the T1 interface. To enter interface configuration mode and configure the serial interface that corresponds to a T1 channel group, use the following command in global configuration mode.

For more information, see the "Configuring Each T1 Channel" section and the "Specifying a Synchronous Serial Interface" section.

For an example of configuring an external T1 channel, see the "Channelized T3 Interface Processor Configuration: Examples" section.

Monitoring and Maintaining the CT3IP

After configuring the new interface, you can monitor the status and maintain the CT3IP in the Cisco 7000 series routers with an RSP7000 or in the Cisco 7500 series routers by using the show commands. To display the status of any interface, use one of the following commands in EXEC mode.

Verifying T3 Configuration

To verify your software configuration, you can use show commands for controller settings. To use show commands, you must be in privileged EXEC mode.

Router# show controller t3

T3 1/0/0 is up.

 Applique type is Channelized T3

 No alarms detected.

 FEAC code received: No code is being received

 Framing is M23, Line Code is B3ZS, Clock Source is Line.

 Data in current interval (751 seconds elapsed):

     0 Line Code Violations, 0 P-bit Coding Violation

     0 C-bit Coding Violation, 0 P-bit Err Secs

     0 P-bit Severely Err Secs, 0 Severely Err Framing Secs

     0 Unavailable Secs, 0 Line Errored Secs

     0 C-bit Errored Secs, 0 C-bit Severely Errored Secs

 Total Data (last 16 15 minute intervals):

     0 Line Code Violations, 0 P-bit Coding Violation,

     0 C-bit Coding Violation, 0 P-bit Err Secs,

     0 P-bit Severely Err Secs, 0 Severely Err Framing Secs,

     0 Unavailable Secs, 0 Line Errored Secs,

     0 C-bit Errored Secs, 0 C-bit Severely Errored Secs

Tip•To use the controller, it must report being up.

•No errors should be reported.

Configuring Maintenance Data Link Messages

The CT3IP can be configured to send a Maintenance Data Link (MDL) message as defined in the ANSI T1.107a-1990 specification. To specify the transmission of the MDL messages, use the following commands beginning in global configuration mode.

Specify one mdl command for each message. For example, use mdl string eic Router A to transmit "Router A" as the equipment identification code and use mdl string lic Test Network to transmit "Test Network" as the location identification code.

Use the show controllers t3 command to display MDL information (received strings). MDL information is displayed only when framing is set to C-bit.

Enabling Performance Report Monitoring

The CT3IP supports performance reports via the Facility Data Link (FDL) per ANSI T1.403. By default, performance reports are disabled. To enable FDL performance reports, use the following commands beginning in global configuration mode.

Note Performance reporting is available only on T1 channels configured for ESF framing.

To display the remote performance report information, use the following command in EXEC mode.

Configuring for BERT on the Cisco AS5300

Bit-error rate testing (BERT) and loopbacks are used by carriers and Internet service providers (ISPs) to aid in problem resolution as well as testing the quality of T1/E1 links. BERT detects poor quality links early and isolates problems quickly, enabling Cisco AS5300 users to improve their quality of service and increase their revenues.

BERT is available for the Cisco AS5300 router for T1 and E1 facilities. Perform the following tasks to configure the Cisco AS5300 router for BERT, use the following commands beginning in user EXEC mode.

Verifying BERT on the Cisco AS5300

To verify that a BERT feature is running, use the show running-config command in EXEC mode.

5300> show running-config

!

bert profile 1 pattern 1s threshold 10^-4 error-injection none duration 3

bert profile 7 pattern 220-O.151QRSS threshold 10^-3 error-injection 10^-5 duration 120

Enabling a BERT Test Pattern

To enable and disable generation of a BERT test pattern for a specified interval for a specific T1 channel, use the following commands beginning in global configuration mode.

The BERT test patterns from the CT3IP are framed test patterns (that is, the test patterns are inserted into the payload of the framed T1 signal).

To view the BERT results, use the show controllers t3 or show controllers t3 brief EXEC command. The BERT results include the following information:

•Type of test pattern selected

•Status of the test

•Interval selected

•Time remaining on the BERT test

•Total bit errors

•Total bits received

When the T1 channel has a BERT test running, the line state is DOWN. Also, when the BERT test is running and the Status field is Not Sync, the information in the total bit errors field is not valid. When the BERT test is done, the Status field is not relevant.

The t1 bert pattern command is not written to NVRAM because it is only used for testing the T1 channel for a short predefined interval and to avoid accidentally saving the command, which could cause the interface not to come up the next time the router reboots.

Enabling Remote FDL Loopbacks

You can perform the following types of remote Facility Data Link (FDL) loopbacks on a T1 channel:

•Remote payload FDL ANSI—Sends a repeating, 16-bit Extended Superframe (ESF) data link code word (00010100 11111111) to the remote end requesting that it enter into a network payload loopback.

•Remote line FDL ANSI—Sends a repeating, 16-bit ESF data link code word (00001110 11111111) to the remote CSU end requesting that it enter into a network line loopback.

•Remote line FDL Bellcore—Sends a repeating, 16-bit ESF data link code word (00010010 11111111) to the remote SmartJack end requesting that it enter into a network line loopback.

To enable loopback on a T1 channel, use the following commands beginning in global configuration mode.

Note The port adapter and port numbers for the CT3IP are 0.

Configuring T1 Cable Length and T1/E1 Line Termination

When you configure your channelized T1 trunk cards, you can change the line build-out of the cable pair connected to the port. To specify the build-out value, use either the cablelength long command or the cablelength short command. These commands are not required for E1 trunk cards.

For cables longer than 655 feet, use the cablelength long command; for cables up to and including 655 feet, use the cablelength short command.

The line-termination command allows you to set the T1/E1 port termination to 75 ohms unbalanced or 120 ohms balanced.

The following cable length short configurations define the length range (in feet) between your network access server (NAS) and your repeater. The cablelength short command is configured for a channelized T1 only and includes the following settings:

•133 feet (0 to 133 feet)

•266 feet (134 to 266 feet)

•399 feet (267 to 399 feet)

•533 feet (400 to 533 feet)

•655 feet (534 to 655 feet)

Note Although you can specify a cable length from 0 to 655 feet, the hardware only recognizes fixed configuration lengths. For example, if your cable length is 50 feet between your NAS and your repeater, you should configure your cable length using the 133-feet setting. If you later change the cable length to 200 feet, you should reconfigure your cable length using the 266-feet setting.

The following cable length long configurations define the length range in gain and pulse requirements for the length of build-out between your NAS and your repeater that is longer than 655 feet. The cablelength long command is configured for a channelized T1 only and includes the following gain and pulse settings:

•gain26 (26 dB gain)

•gain36 (36 dB gain)

•-15db (-15 dB pulse)

•-22.5db (-22.5 dB pulse)

•-7.5db (-7.5 dB pulse)

•0db (0 dB pulse)

To configure channelized T1 lines for line build-out, use the following commands beginning in user EXEC mode.

Configuring PA-E3 and PA-2E3 Serial Port Adapters

The PA-E3 and PA-2E3 serial port adapters are available on:

•Cisco 7200 series routers

•Cisco 7500 series routers

•Cisco 7000 series routers with the 7000 series Route Switch Processor (RSP7000) and 7000 series Chassis Interface (RSP7000CI)

These port adapters provide one (PA-E3) or two (PA-2E3) high-speed, full-duplex, synchronous serial E3 interfaces and integrated data service unit (DSU) functionality.

The E3 port adapters can transmit and receive data at E3 rates of up to 34 Mbps and use a 75-ohm coaxial cable available from Cisco to connect to a serial E3 network. These port adapters support the following:

•16- and 32-bit cyclic redundancy checks (CRCs)

•High-speed HDLC data

•G.751 framing or bypass

•HDB3 line coding

•ATM-DXI, Frame Relay, HDLC, PPP, and SMDS serial encapsulation

•National service bits

•E3 MIB (RFC 1407)

•Scrambling and reduced bandwidth

•Remote and local loopbacks

The PA-E3 port adapter supports the RFC 1407 DS3 Near End Group, including:

•DS3/E3 Configuration Table

•DS3/E3 Current Table

•DS3/E3 Interval Table

•DS3/E3 Total Table

The PA-E3 port adapter also supports the Card Table in the Cisco Chassis MIB and the MIB-2 for each PA-E3 interface.

The PA-E3 port adapter does not support the RFC 1407 DS3 Far End Group and DS3/E3 Fractional Group.

Note For additional information on the E3 serial port adapter, refer to the PA-E3 Serial Port Adapter Installation and Configuration publication.

PA-E3 and PA-2E3 Serial Port Adapter Configuration Task List

To configure the PA-E3, Perform the tasks in the following sections. Each task in the list is identified as either required or optional.

•Configuring the PA-E3 Port Adapter (Required)

•Monitoring and Maintaining the PA-E3 Port Adapter (Optional)

For PA-E3 port adapter configuration examples, see the "PA-E3 Serial Port Adapter Configuration: Example" section.

Configuring the PA-E3 Port Adapter

The commands listed in Table 3 have been added to support the PA-E3 interface configuration. If you do not modify the configuration of the PA-E3, the configuration defaults shown in Table 3 are used.

If you need to change any of the default configuration attributes, use the first command in global configuration mode, followed by any of the optional commands in interface configuration mode.

Monitoring and Maintaining the PA-E3 Port Adapter

After configuring the new interface, you can display its status. To show current status of the E3 interface on the PA-E3 port adapter, use any of the following commands in EXEC mode.

Configuring PA-T3 and PA-2T3 Serial Port Adapters

The PA-T3 and PA-2T3 serial port adapters are available on:

•Cisco 7200 series routers

•Second-generation Versatile Interface Processor (VIP2) in all Cisco 7500 series routers

•Cisco 7000 series routers with the 7000 series Route Switch Processor (RSP7000) and 7000 series Chassis Interface (RSP7000CI)

These port adapters provide one (PA-T3) or two (PA-2T3) high-speed, full-duplex, synchronous serial T3 interfaces and integrated data service unit (DSU) functionality.

The T3 port adapters can transmit and receive data at T3 rates of up to 45 Mbps and use a 75-ohm coaxial cable available from Cisco to connect to a serial T3 network. These port adapters support the following features:

•16- and 32-bit cyclic redundancy checks (CRCs)

•High-speed HDLC data

•C-bit, M13, and bypass framing

•HDB3 line coding

•ATM-DXI, Frame Relay, HDLC, PPP, and SMDS serial encapsulation

•DS3 MIB (RFC 1407)

•Scrambling and reduced bandwidth

•Remote and local loopbacks

Note For additional information on interoperability guidelines for T3 serial port adapter DSUs, refer to the PA-T3 Serial Port Adapter Installation and Configuration publication.

PA-T3 and PA-2T3 Port Adapter Configuration Task List

To configure the PA-T3 port adapters, perform the tasks in the following sections. Each task is identified as either required or optional.

•Configuring the PA-T3 Port Adapter (Required)

•Troubleshooting the PA-T3 Port Adapter (Optional)

•Monitoring and Maintaining the PA-T3 Port Adapter (Optional)

For PA-T3 port adapter configuration examples, see the "PA-T3 and PA-2T3 Configuration: Example" section.

Configuring the PA-T3 Port Adapter

The commands listed in Table 4 have been added to support the PA-T3 interface configuration. If you do not modify the configuration of the PA-T3, the configuration defaults shown in Table 4 are used.

If you need to change any of the default configuration attributes, use the first command in global configuration mode, followed by any of the optional commands in interface configuration mode.

Troubleshooting the PA-T3 Port Adapter

To set the following loopback modes to troubleshoot the PA-T3 port adapter using Cisco IOS software, use the first command in global configuration mode, followed by any of the other commands depending on your needs:

These loopback commands loop all packets from the T3 interface back to the interface or direct packets from the network back out toward the network.

Monitoring and Maintaining the PA-T3 Port Adapter

After configuring the new interface, you can display its status. To show current status of the T3 interface on the PA-T3 port adapter, use any of the following commands in EXEC mode.

Configuring a Packet OC-3 Interface

The Cisco Packet OC-3 Interface Processor (POSIP) and Packet OC-3 Port Adapter (POSPA) are available on:

•Cisco 7500 series routers

•Cisco 7200 series routers

The Packet-Over-SONET OC-3 port adapters (PA-POS-OC3SML, PA-POS-OC3SMI, and PA-POS-OC3MM) are available on:

•Cisco 7500 series routers

•Cisco 7200 series routers

•Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI)

The POSIP and POS OC-3 provide a single 155.520-Mbps, OC-3 physical layer interface for packet-based traffic. This OC-3 interface is fully compatible with SONET and Synchronous Digital Hierarchy (SDH) network facilities and is compliant with RFC 1619, "PPP over SONET/SDH," and RFC 1662, PPP in HDLC-like Framing. The Packet-Over-SONET specification is primarily concerned with the use of PPP encapsulation over SONET/SDH links.

For more information on the PA-POS-OC3 port adapter, refer to the PA-POS-OC3 Packet OC-3 Port Adapter Installation and Configuration publication that accompanies the hardware.

The POS is a fixed-configuration interface processor that uses second-generation Versatile Interface Processor (VIP2) technology. The POS provides a single 155.520-Mbps, OC-3 physical layer interface for packet-based traffic. This OC-3 interface is fully compatible with SONET and SDH network facilities and is compliant with RFC 1619 and RFC 1662. The Packet-Over-SONET specification primarily addresses the use of PPP encapsulation over SONET/SDH links.

Table 5 describes the default values set in the initial configuration of a Packet OC-3 interface.

Because the Packet OC-3 interface is partially configured, you might not need to change its configuration before enabling it. However, when the router is powered up, a new Packet OC-3 interface is shut down. To enable the Packet OC-3 interface, you must use the no shutdown command in the global configuration mode.

Packet OC-3 Interface Configuration Task List

The values of all Packet OC-3 configuration parameters can be changed to match your network environment. To customize the POS configuration, perform the tasks in the following sections. Each task in the list is identified as either required or optional.

•Selecting a Packet OC-3 Interface (Optional)

•Setting the MTU Size (Optional)

•Configuring Framing (Optional)

•Configuring an Interface for Internal Loopback (Optional)

•Configuring an Interface for Line Loopback (Optional)

•Setting the Source of the Transmit Clock (Optional)

•Enabling Payload Scrambling (Optional)

•Configuring an Alarm Indication Signal (Optional)

Selecting a Packet OC-3 Interface

The Packet OC-3 interface is referred to as pos in the configuration commands. An interface is created for each POS found in the system at reset time.

If you need to change any of the default configuration attributes or otherwise reconfigure the Packet OC-3 interface, use one the following commands in global configuration mode.

Setting the MTU Size

To set the maximum transmission unit (MTU) size for the interface, use the following command in interface configuration mode.

The value of the bytes argument is in the range 64 to 4470 bytes; the default is 4470 bytes (4470 bytes exactly matches FDDI and HSSI interfaces for autonomous switching). The no form of the command restores the default.

Caution Changing an MTU size on a Cisco 7500 series router will result in resizing and reassignment of buffers and resetting of all interfaces. The following message is displayed:

%RSP-3-Restart:cbus complex88

Configuring Framing

To configure framing on the Packet OC-3 interface, use one of the following commands in interface configuration mode.

Configuring an Interface for Internal Loopback

With the loopback internal command, packets from the router are looped back in the framer. Outgoing data gets looped back to the receiver without actually being transmitted. With the loopback line command, the receive fiber (RX) is logically connected to the transmit fiber (TX) so that packets from the remote router are looped back to it. Incoming data gets looped around and retransmitted without actually being received.

To enable or disable internal loopback on the interface, use one of the following commands in interface configuration mode.

Local loopback is useful for checking that the POS is working. Packets from the router are looped back in the framer.

Configuring an Interface for Line Loopback

Line loopback is used primarily for debugging purposes.

To enable or disable an interface for line loopback, use one of the following commands in interface configuration mode.

The receive fiber (RX) is logically connected to the transmit fiber (TX) so that packets from the remote router are looped back to it.

Setting the Source of the Transmit Clock

By default, the Packet OC-3 interface uses the recovered receive clock to provide transmit clocking. To change the transmit clock source, use one of the following commands in interface configuration mode.

Enabling Payload Scrambling

SONET payload scrambling applies a self-synchronous scrambler (x43+1) to the Synchronous Payload Envelope (SPE) of the interface to ensure sufficient bit transition density. Both ends of the connection must use the same scrambling algorithm. When enabling POS scrambling on a VIP2 POS on the Cisco 7500 series router that has a hardware revision of 1.5 or higher, you can specify CRC 16 only (that is, CRC 32 is currently not supported).

To enable SONET payload scrambling on a POS interface, use the following command in interface configuration mode.

Configuring an Alarm Indication Signal

To configure line alarm indication signals (LAIS) when the POS interface is placed in any administrative shut down state, use the following command in interface configuration mode.

Configuring a DPT OC-12c Interface

The dual-width OC-12c Dynamic Packet Transport (DPT) port adapter is available on Cisco 7200 series routers and Cisco 7200 VXR series routers with the correct Route Switch Processor (RSP2 or RSP4), running Cisco IOS Release 12.0(6)S or later, to provide shared IP-over-SONET capability.

The OC-12c Dynamic Packet Transport Interface Processor (DPTIP) is available on Cisco 7500 series routers with the correct Route Switch Processor (RSP2 or RSP4), running Cisco IOS Release 12.0(6)S or later. The DPT is an OC-12c interface that uses second-generation Versatile Interface Processor (VIP2) technology to provide shared IP-over-SONET capability, and it complies with IEEE 802.3 specifications for multicast and broadcast media. The DPTIP assembly consists of a VIP2 with a dual-width DPT interface processor permanently attached to it.

The DPT interface provides the following benefits:

•Accommodates large-scale network topology.

•Complies with applicable IEEE 802.3 standards.

•Supports Intelligent Protection Switching (IPS).

The interface type of the DPT or DPTIP is Spatial Reuse Protocol (SRP). SRP is a Cisco-developed MAC-layer protocol, used in conjunction with Cisco's DPT product family. DPT products deliver scalable Internet service, reliable IP-aware optical transport, and simplified network operations. These solutions allow you to scale and distribute your IP services across a reliable optical packet ring infrastructure.

Spatial bandwidth reuse is possible due to the packet destination-stripping property of SRP. Older technologies incorporate source stripping, where packets traverse the entire ring until they are removed by the source. Even if the source and destination nodes are next to each other on the ring, packets continue to traverse the entire ring until they return to the source to be removed. SRP provides more efficient use of available bandwidth by having the destination node remove the packet after it is read. This provides more bandwidth for other nodes on the SRP ring.

SRP rings consists of two counterrotating fibers, known as outer and inner rings, both concurrently used to carry data and control packets. SRP uses both explicit control packets and control information piggybacked inside data packets (control packets handle tasks such as keepalives, protection switching, and bandwidth control propagation). Control packets propagate in the opposite direction from the corresponding data packets, ensuring that the data takes the shortest path to its destination. The use of dual fiber-optic rings provides a high level of packet survivability. In the event of a failed node or a fiber cut, data is transmitted over the alternate ring.

SRP rings are media independent and can operate over a variety of underlying technologies, including SONET/SDH, wavelength division multiplexing (WDM), and dark fiber. This ability to run SRP rings over any embedded fiber transport infrastructure provides a path to packet-optimized transport for high- bandwidth IP networks.

One of the important benefits of SRP is the bandwidth scalability and efficiency with growth opportunities from OC-12c/STM-4c rings up to OC-192c/STM-64c rings.

OC-12c Interface Configuration Task List

To configure the DPT interface, perform the tasks in the following sections. Each task in the list is identified as either required or optional.

•Configuring the Dynamic Packet Transport Interface (Required)

•Configuring Intelligent Protection Switching (Optional)

•Configuring DPT Topology (Optional)

Configuring the Dynamic Packet Transport Interface

The system displays an OK message when the configuration has been stored.

Use the show running-config command to verify the currently running configuration. Use the show version command to display the configuration of the system hardware and the Cisco IOS software information.

Configuring Intelligent Protection Switching

The SRP interface uses ring architecture to provide redundancy and protection from a failed node or a fiber cut by using Intelligent Protection Switching (IPS). To configure IPS, use the following commands beginning in privileged EXEC mode. The steps described in this section are optional.

Use the show srp command to verify the configuration.

Configuring DPT Topology

Every node on a DPT ring maintains a topology map of the ring, so that it knows where to route traffic. It updates the topology map by periodically sending a query, called a topology discovery packet, out onto the outer-ring path. Each node on the ring adds its own MAC address to the packet. When the discovery packet returns to the originating node, the contents of the packet are used to update the topology map. You use the srp topology-timer command to set the frequency with which the node sends out topology discovery packets. To configure DPT, use the following commands beginning in privileged EXEC mode.

Configuring Automatic Protection Switching of Packet-over-SONET Circuits

The automatic protection switching (APS) feature is supported on Cisco 7500 series routers. This feature allows switchover of Packet-over-SONET (POS) circuits and is often required when connecting SONET equipment to telco equipment. APS refers to the mechanism of bringing a "protect" POS interface into the SONET network as the "working" POS interface on a circuit from the intervening SONET equipment.

The protection mechanism used for this feature is "1+1, Bidirectional, nonrevertive" as described in the Bellcore publication "TR-TSY-000253, SONET Transport Systems; Common Generic Criteria, Section 5.3." In the 1+1 architecture, there is one working interface (circuit) and one protect interface, and the same payload from the transmitting end is sent to both the receiving ends. The receiving end decides which interface to use. The line overhead (LOH) bytes (K1 and K2) in the SONET frame indicate both status and action.

The protect interface is configured with the IP address of the router that has the working interface. The APS Protect Group Protocol, which runs on top of UDP, provides communication between the process controlling the working interface and the process controlling the protect interface. Using this protocol, POS interfaces can be switched because of a router failure, degradation or loss of channel signal, or manual intervention. In bidirectional mode, the receive and transmit channels are switched as a pair. In unidirectional mode, the transmit and receive channels are switched independently. For example, if the receive channel on the working interface has a loss of channel signal, both the receive and transmit channels are switched.

In addition to the new Cisco IOS commands added for the APS feature, the POS interface configuration commands pos threshold and pos report have been added to support user configuration of the bit-error rate (BER) thresholds and reporting of SONET alarms.

APS Configuration Task List

Two SONET connections are required to support APS. In a telco environment, the SONET circuits must be provisioned as APS. You must also provision the operation (for example, 1+1), mode (for example, bidirectional), and revert options (for example, no revert). If the SONET connections are homed on two separate routers (the normal configuration), an out of band (OOB) communications channel between the two routers needs to be set up for APS communication.

When configuring APS, we recommend that you configure the working interface first. Normal operation with 1+1 operation is to configure it as a working interface. Also configure the IP address of the interface being used as the APS OOB communications path.

For more information on POS interfaces, refer to the installation and configuration documentation that accompanies the POS hardware.

To configure APS and POS, perform the following tasks. Each task is identified as either required or optional.

•Configuring APS Working and Protect Interfaces (Required)

•Configuring Other APS Options (Optional)

•Monitoring and Maintaining APS (Optional)

•Configuring SONET Alarm Reporting (Optional)

•Configuring a Protection Switch (Optional)

Configuring APS Working and Protect Interfaces

This section describes how to configure and protect a working interface. The commands listed in this section are required. To avoid having the protected interface become the active circuit and disabling the working circuit when it is discovered, configure the working interface before configuring the protected interface.

To configure the working interface, use the following commands beginning in global configuration mode.

Note If a router has two or more protect interfaces, the aps group command for each interface must precede the corresponding aps protect command.

To configure the protect interface, use the following commands beginning in global configuration mode.

Configuring Other APS Options

To configure the other APS options, use any of the following optional commands in interface configuration mode.

Monitoring and Maintaining APS

To provide information about system processes, the Cisco IOS software includes an extensive list of EXEC commands that begin with the word show, which, when executed, display detailed tables of system information. Following is a list of some of the common show commands for the APS feature.

To display the information described, use these commands in privileged EXEC mode.

Configuring SONET Alarm Reporting

To configure the thresholds and the type of SONET alarms that are reported, use any of the following commands in interface configuration mode. The commands listed in this section are optional. The default settings are adequate for most POS installations.

To display the current BER threshold setting or to view the reporting of the SONET alarms, use the show controllers pos EXEC command.

Configuring a Protection Switch

LAIS can be used to force a protection switch in an APS environment. To force an APS switch when the interface is placed in administrative shut down state, use the following command in interface configuration mode.

Configuring Serial Interfaces for CSU/DSU Service Modules

The Cisco T1 data service unit/channel service unit (DSU/CSU) WAN interface card is an integrated, managed T1 or fractional T1 WAN interface card. It provides nonchannelized data rates of 1 to 24 X 64 kbps or 1 to 24 X 56 kbps and follows ANSI T1.403 and AT&T Publication 62411 standards.

The Cisco DSU/CSU WAN T1 interface includes the following management features:

•You can remotely configure the interface using Telnet and the Cisco IOS command-line interface (CLI).

•For monitoring purposes, the router and DSU/CSU are manageable as a single Simple Network Management Protocol (SNMP) entity using CiscoWorks or CiscoView. DSU/CSU statistics are accessed from the CLI.

•The SNMP agent supports the standard MIB II, Cisco integrated DSU/CSU MIB, and T1 MIB (RFC 1406).

•Loopbacks (including a manual button for a network line loopback) and bit error rate tester (BERT) tests are provided for troubleshooting.

•Test patterns, alarm counters, and performance reports are accessible using the CLI.

•The module has carrier detect, loopback, and alarm LEDs.

The following CSU and DSU service modules are described in this section:

•Fractional T1/FT/WIC CSU/DSU service module

•2-wire and 4-wire, 56/64-kbps CSU/DSU service module

Fractional T1/FT/WIC CSU/DSU Service Module Configuration Task List

To configure fractional T1 and T1 (FT1/T1) service modules, perform the tasks described in these sections. Each task in the list is identified as either required or optional.

•Specifying the Clock Source (Required)

•Enabling Data Inversion Before Transmission (Required)

•Specifying the Frame Type of an FT/T1 Line (Required)

•Specifying the CSU Line Build-Out (Required)

•Specifying FT1/T1 Line-Code Type (Required)

•Enabling Remote Alarms (Optional)

•Enabling Loop Codes That Initiate Remote Loopbacks (Optional)

•Specifying Time Slots (Required)

•Enabling the T1 CSU WIC (Required)

Specifying the Clock Source

To specify the clock source (that is, the source of the timing synchronization signal) for the FT1/T1 CSU/DSU module, use the following command in interface configuration mode.

Enabling Data Inversion Before Transmission

Data inversion is used to guarantee the ones density requirement on an alternate mark inversion (AMI) line when using bit-oriented protocols such as High-Level Data Link Control (HDLC), PPP, X.25, and Frame Relay.

To guarantee the ones density requirement on an AMI line using the FT1/T1 CSU/DSU module, use the following command in interface configuration mode.

If the time-slot speed is set to 56 kbps, this command is rejected because line density is guaranteed when transmitting at 56 kbps. Use this command with the 64-kbps line speed. If you transmit inverted bit codes, both CSU/DSUs must have this command configured for successful communication.

To enable normal data transmission on an FT1/T1 network, use the following command in interface configuration mode.

Specifying the Frame Type of an FT/T1 Line

To specify the frame type for a line using the FT1/T1 CSU/DSU module, use the following command in interface configuration mode.

In most cases, the service provider determines which framing type, either sf or esf, is required for your circuit.

Specifying the CSU Line Build-Out

To decrease the outgoing signal strength to an optimum value for the telecommunication carrier network, use the following command on the FT1/T1 CSU/DSU module in interface configuration mode.

To transmit packets without decreasing outgoing signal strength, use the following command in interface configuration mode.

The ideal signal strength should be between -15 dB and -22 dB, which is calculated by adding the phone company loss plus cable length loss plus line build out. You may use this command in back-to-back configurations, but it is not needed on most actual T1 lines.

Specifying FT1/T1 Line-Code Type

To configure the line code for the FT1/T1 CSU/DSU module, use the following command in interface configuration mode.

Configuring B8ZS is a method of ensuring the ones density requirement on a T1 line by substituting intentional bipolar violations in bit positions four and seven for a sequence of eight zero bits. When you configure the CSU/DSU AMI, you must guarantee the ones density requirement in your router using the service-module t1 data-coding inverted command or the service-module t1 timeslots speed 56 command. In most cases, your T1 service provider determines which line-code type, either ami or b8zs, is required for your T1 circuit.

Enabling Remote Alarms

To generate remote alarms (yellow alarms) at the local CSU/DSU or to detect remote alarms sent from the remote CSU/DSU, use the following command in interface configuration mode.

Remote alarms are transmitted by the CSU/DSU when it detects an alarm condition, such as a red alarm (loss of signal) or blue alarm (unframed 1s). The receiving CSU/DSU then knows that there is an error condition on the line.

With D4 Superframe configured, a remote alarm condition is transmitted by setting the bit 2 of each time slot to zero. For received user data that has bit 2 of each time slot set to zero, the CSU/DSU interprets the data as a remote alarm and interrupts data transmission, which explains why remote alarms are disabled by default. With Extended Super Frame configured, the remote alarm condition is signalled out of band in the facility data link.

You can see if the FT1/T1 CSU/DSU is receiving a remote alarm (yellow alarm) by issuing the show service-module command.

To disable remote alarms, use the following command in interface configuration mode.

Enabling Loop Codes That Initiate Remote Loopbacks

To specify if the fractional T1/T1 CSU/DSU module goes into loopback when it receives a loopback code on the line, use the following commands in interface configuration mode.

Note By using the service-module t1 remote-loopback command without specifying any keywords, you enable the standard-loopup codes, which use a 1-in-5 pattern for loopup and a 1-in-3 pattern for loopdown.

You can simultaneously configure the full and payload loopback points. However, only one loopback payload code can be configured at a time. For example, if you configure the service-module t1 remote-loopback payload alternate command, a payload v.54 request, which is the industry standard and default, cannot be transmitted or accepted. Full and payload loopbacks with standard-loopup codes are enabled by default.

The no form of this command disables loopback requests. For example, the no service-module t1 remote-loopback full command ignores all full-bandwidth loopback transmissions and requests. Configuring the no form of the command may not prevent telco line providers from looping your router in esf mode, because fractional T1/T1 telcos use facilities data-link messages to initiate loopbacks.

If you enable the service-module t1 remote-loopback command, the loopback remote commands on the FT1/T1 CSU/DSU module will not be successful.

Specifying Time Slots

To define time slots for an FT1/T1 module, use the following command in interface configuration mode.

This command specifies which time slots are used in fractional T1 operation and determines the amount of bandwidth available to the router in each time slot. The range specifies the DS0 time slots that constitute the FT1/T1 channel. The range is from 1 to 24, where the first time slot is numbered 1, and the last time slot is numbered 24. Specify this field by using a series of subranges separated by commas. The time-slot range must match the time slots assigned to the channel group. In most cases, the service provider defines the time slots that comprise a channel group. Use the no form of this command to select all FT1/T1 time slots that are transmitting at 64 kbps, which is the default.

To use the entire T1 line, enable the service-module t1 timeslots all command.

Enabling the T1 CSU WIC

The following are prerequisites to enable the T1 CSU WIC:

•Leased line from your telephone company

•Configuration parameters depending on your specific telephone company. For most connections, the default settings should suffice:

–service-module t1 clock source line

–service-module t1 data-coding normal

–service-module t1 timeslots all speed 64

–service-module t1 framing esf

–service-module t1 lbo none

–service-module t1 linecode b8zs

–no service-module t1 remote-alarm-enable

–no service-module t1 fdl

Note To view the current configuration, use the show service-module serial slot/port command. For further information about these commands and how to change them, refer to the Cisco IOS configuration guides and command references that shipped with your router.

To configure the router to send SNMP traps, use the following commands:

2-Wire and 4-Wire, 56/64-kbps CSU/DSU Service Module Configuration Task List

To configure 2- and 4-wire, 56/64 kbps service modules, perform the tasks described in these sections:

•Setting the Clock Source

•Setting the Network Line Speed

•Enabling Scrambled Data Coding

•Changing Between Digital Data Service and Switched Dial-Up Modes

•Enabling Acceptance of a Remote Loopback Request

•Selecting a Service Provider

Setting the Clock Source

In most applications, the CSU/DSU should be configured using the service-module 56k clock source line command. For back-to-back configurations, use the internal keyword to configure one CSU/DSU and use the line keyword to configure the other CSU/DSU.

To configure the clock source for a 4-wire, 56/64-kbps CSU/DSU module, use the following command in interface configuration mode for a serial interface:

Use the no form of this command to revert to the default clock source, which is the line clock.

Setting the Network Line Speed

To configure the network line speed for a 4-wire, 56/64-kbps CSU/DSU module, use the following command in interface configuration mode for a serial interface:

You can use the following line speed settings: 2.4, 4.8, 9.6, 19.2, 38.4, 56, 64 kbps, and an auto setting.

The 64-kbps line speed cannot be used with back-to-back digital data service (DDS) lines. The subrate line speeds are determined by the service provider.

Only the 56-kbps line speed is available in switched mode. Switched mode is the default on the 2-wire CSU/DSU and is enabled by the service-module 56k network-type interface configuration command on the 4-wire CSU/DSU.

The auto linespeed setting enables the CSU/DSU to decipher current line speed from the sealing current running on the network. Because back-to-back DDS lines do not have sealing current, use the auto setting only when transmitting over telco DDS lines and using the line clock as the clock source.

Use the no form of this command to enable a network line speed of 56 kbps, which is the default.

Enabling Scrambled Data Coding

To prevent application data from replicating loopback codes when operating at 64 kbps on a 4-wire CSU/DSU, use the following command in interface configuration mode for a serial interface:

Enable the scrambled configuration only in 64 kbps DDS mode. If the network type is set to switched, the configuration is refused.

If you transmit scrambled bit codes, both CSU/DSUs must have this command configured for successful communication.

To enable normal data transmission for the 4-wire, 56/64-kbps module, use one of the following commands for a serial interface in interface configuration mode.

Changing Between Digital Data Service and Switched Dial-Up Modes

To transmit packets in DDS mode or switched dial-up mode using the 4-wire, 56/64-kbps CSU/DSU module, use one of the following commands in interface configuration mode for a serial interface: