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Feature Name |
Release Information |
Description |
|---|---|---|
|
48-Port T1/E1 CEM Interface Module support in ASR-920-12SZ-IM |
Cisco IOS XE Cupertino 17.8.1 |
The router supports the following features for the 48-Port T1/E1 Circuit Emulation (CEM) interface module:
The support for the interface module provides cost-effective delivery of CEM over a packet-based network (MPLS). |
The T1 or E1 interface module delivers T1 or E1 connectivity on the router with the RSP3 module. The module can be software configured as either T1 mode or E1 mode per interface module The module provides physical connectivity using a single high-density connector and requires a breakout cable and patch panel for individual port connections.
The T1 or E1 interface module supports the following modes:
T1
E1
 Note |
Mixing T1 and E1 ports on the same interface module is not supported. |
CEM configurations are supported on different modes on the interface module. The troubleshooting, monitoring, and redundancy features are supported on the module. The module can be clocked from a line or from an internal clock source. The table describes the configurations and features for the modes that are supported on the T1 or E1 interface module.
| T1 | E1 | |
|---|---|---|
|
Required Configurations |
||
|
Mode |
Yes |
Yes |
|
Internal/Line Clock Source |
Yes |
Yes |
|
ACR/DCR Clock |
Yes |
Yes |
|
CEM Configurations |
||
|
Structure-Agnostic TDM over Packet (SATOP) (Framed/Unframed) |
Yes |
Yes |
|
Circuit Emulation over Packet-Switched Network (CESoPSN) |
Yes |
Yes |
|
Troubleshooting Features |
||
|
Bit Error Rate Testing (BERT) |
Yes |
Yes |
|
Loopback |
Yes |
Yes |
|
Monitoring Features |
||
|
Performance Monitoring |
Yes |
Yes |
You can configure CEM to support serial interface configuration.
The card can be configured either in the T1 or E1 mode. A combination of T1 and E1 ports is not supported.
Circuit Emulation (CEM) is a technology that provides a protocol-independent transport over IP/MPLS networks. It enables proprietary or legacy applications to be carried transparently to the destination, similar to a leased line.
CEM provides a bridge between a Time-Division Multiplexing (TDM) network and a Multiprotocol Label Switching (MPLS) network. The router encapsulates the TDM data in the MPLS packets and sends the data over a CEM pseudowire to the remote Provider Edge (PE) router. As a result, CEM functions as a physical communication link across the packet network.
The router supports the pseudowire type that utilizes CEM transport: Structure-Agnostic TDM over Packet (SAToP) and Circuit Emulation Service over Packet-Switched Network (CESoPSN).
L2VPN over IP/MPLS is supported on the interface modules.
Note |
We recommend that you configure the controller in the administratively up mode. Configuration under the administratively down mode is not recommended and it might cause configuration errors. |
Note |
The default behaviour of the CEM pseudowire is always UP irrespective of the controller alarms. |
Pseudowires manage encapsulation, timing, order, and other operations in order to make it transparent to users. The pseudowire tunnel acts as an unshared link or circuit of the emulated service. CEM is a way to carry TDM circuits over packet switched network. CEM embeds the TDM circuits into packets, encapsulates them into an appropriate header, and then sends that through Packet Switched Network. The receiver side of CEM restores the TDM circuits from packets.
Cisco Pseudowire Emulation Edge-to-Edge (PWE3) allows you to transport traffic by using traditional services such as T1/E1 over a packet-based backhaul technology such as MPLS or IP. A pseudowire (PW) consists of a connection between two provider edge (PE) chassis that connects two attachment circuits (ACs), such as T1/E1 or T3 /E3 links.
Framed Structure-Agnostic TDM over Packet (SAToP) is required to detect an incoming AIS alarm in the DS1 SAToP mode. An AIS alarm indicates a problem with the line that is upstream from the DS1 network element connected to the interface. Framed SAToP further helps in the detection of a packet drop.
In case of unframed mode of SAToP, data received from the Customer Edge (CE) device is transported ove the pseudowire. If the Provider Edge (PE) device receives a Loss of Frame (LOF) signal or Remote Alarm Indication (RAI) signal from a CE, the PE can only transmit the signal that is detected by the CE device. With the introduction of Framed SAToP, when the PE device receives the LOF or RAI signal, the PE device can detect the alarm for SAToP. Thus, the alarm can be detected earlier in the network. This helps in enhanced performance.
Note |
Framing type should be maintained same in all routers end to end. |
Difference between Framed and Unframed SAToP:
For unframed SAToP, the incoming signal is transmitted to the far end. This signal is not analyzed by the PE device. Hence, no alarm is reported.
For framed SAToP, the incoming signal is analyzed but is not terminated. If a LOF or RAI signal is detected, the remote PE detects the signals and transmits towards the remote CE.
Difference between Framed SAToP and CESoP:
| Modes |
Alarm Detected at PE |
Controller Status at PE |
Alarm Detected at CE (Remote) |
Framing Bits Generationat PE (Remote) |
Framing Bits Terminated at PE (Remote) |
|---|---|---|---|---|---|
|
Unframed SAToP |
None |
Up |
LOF |
No |
No |
|
Framed SAToP |
LOF |
Down (Data path remians up) |
Yes |
No |
|
|
CESOP |
LOF |
Down (Data path remians up) |
AIS |
Yes |
Yes |
| Modes |
Alarm Detected at PE |
Controller Status at PE |
Alarm Detected at CE (Remote) |
Framing Bits Generation at PE (Remote) |
Framing Bits Terminated at PE (Remote) |
|---|---|---|---|---|---|
|
Unframed SAToP |
None |
Up |
RDI |
No |
No |
|
Framed SAToP |
RDI |
Down (data path remains up) |
RDI |
No |
No |
|
CESOP |
RDI |
Down (data path remains up) |
RDI |
M-bit is set into control word |
Yes |
|
Modes |
Alarm Detected at PE |
Controller Status at PE |
Alarm Detected at CE (Remote) |
Framing Bits Generation at PE (Remote) |
Framing Bits Terminated at PE (Remote) |
|---|---|---|---|---|---|
|
Unframed SAToP |
AIS |
Down (data path remains up) |
AIS |
No |
No |
|
Framed SAToP |
AIS |
Down (data path remains up) |
AIS |
No |
No |
|
CESOP |
AIS |
Down (data path remains up) |
AIS |
L-bit is set into control word |
Yes |
Remote Loopback from CE to PE Detection:
Framed SAToP does not detect any loopback.
|
Loopback Detected at PE |
Controller Status at PE (Remote) |
Controller Status at CE (Remote) |
|
|---|---|---|---|
|
Unframed SAToP |
No |
Not in Loopback |
Loopback |
|
Framed SAToP |
No |
Not in Loopback |
Loopback |
|
CESOP |
Yes |
Loopback |
Not in loopback |
CESoPSN is a method for encapsulating structured (NxDS0) TDM signals as pseudowires over packet switching networks.
The maximum number of CEM interface supported is 192.
DS0 loopback is not supported on the T1 interface.
Alarm forwarding is not supported on the T1 interface.
Card protection is not supported on the T1 interface.
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