PacketCable is a program initiative from Cablelabs and its associated vendors to establish a standard way of providing packet-based, real-time video and other multimedia traffic over hybrid fiber-coaxial (HFC) cable networks. The PacketCable specification is built upon the Data-over-Cable System Interface Specifications (DOCSIS) 1.1, but it extends the DOCSIS protocol with several other protocols for use over noncable networks, such as the Internet and the public switched telephone network (PSTN).

This allows PacketCable to be an end-to-end solution for traffic that originates or terminates on a cable network, simplifying the task of providing multimedia services over an infrastructure composed of disparate networks and media types. It also provides an integrated approach to end-to-end call signaling, provisioning, quality of service (QoS), security, billing, and network management.

The PacketCable Emergency 911 cable interface line card prioritization feature enables cable interface line cards that are supporting an Emergency 911 call to be given automatic priority over cable interface line cards supporting non-emergency voice calls, even in the case of HCCP switchover events. In such cases, Protect HCCP line card interfaces automatically prioritize service to Emergency 911 voice calls, should Working HCCP cable interface line cards be disrupted. This feature is enabled by default, and may not be disabled with manual configuration.

Note	Emergency 911 cable interface line card prioritization applies only to PacketCable voice calls.

During HCCP switchover events, cable modems recover in the following sequence:

1. Cable modems supporting Emergency 911 voice traffic
2. Cable modems supporting non-emergency voice traffic
3. Cable modems that are nearing a T4 timeout event, in which service would be disrupted
4. Remaining cable modems

To view information about Emergency 911 voice events and cable interface line card prioritization on the Cisco CMTS router, use the show hccp, show cable calls, and show hccp event-history commands in privileged EXEC mode.

The enhanced informational support for PacketCable Emergency 911 calls on the Cisco CMTS router provides the following information and related history:

• active Emergency 911 calls
• recent Emergency 911 calls
• regular voice calls
• voice calls made after recent Emergency 911 calls

This feature is enabled and supported with the following configuration and show commands:

• cable high-priority-call-window
• show cable calls
• show cable modem calls

To set the call window (in minutes) during which the Cisco CMTS router maintains records of Emergency 911 calls, use the cable high-priority-call-window command in global configuration mode. To remove the call window configuration from the Cisco CMTS router, use the no form of this command:

A PacketCable network contains a number of components. Some components are the same as those that exist in a DOCSIS 1.1 network, while other components are new entities that create the end-to-end infrastructure that the PacketCable network needs to establish calls. Wherever possible, the PacketCable components and protocols build on existing protocols and infrastructures to simplify implementation and interoperability.

• Cable modem—A customer premises equipment (CPE) device that connects to a DOCSIS 1.0 or DOCSIS 1.1 cable network. All DOCSIS cable modems provide high-speed data connectivity to the Internet, while other cable modems can provide additional features, such as telephone connectivity.
• Cable Modem Termination System (CMTS)—A headend-based router that connects a DOCSIS cable network to the IP backbone network. The CMTS controls the DOCSIS 1.1 MAC layer and enforces the quality of service (QoS) limits that the cable operator guarantees to its subscribers. A typical CMTS services between several hundred and several thousand cable modems.

Note	See the DOCSIS 1.1 specifications for information about cable modem and CMTS operations.

• Multimedia terminal adapter (MTA)—A CPE device that connects telephones and other end-user devices to the PacketCable network. The PacketCable specification defines two MTA types, an embedded MTA (E-MTA) and a standalone MTA (S-MTA). The E-MTA is an MTA integrated into a DOCSIS 1.1 cable modem, while the S-MTA is a separate MTA that requires a DOCSIS 1.1 cable modem to connect to the cable network.
• Call management server (CMS)—A centrally located server that provides the signaling functions that allow MTAs to establish calls over the network. The CMS uses the Network-based call signaling (NCS) protocol to provide authentication and authorization, call routing, and support for special features such as three-way calling. A PacketCable network could have multiple CMS servers, depending on its size and complexity.

Note	The CMS implements several protocols on top of the Common Open Policy Service (COPS) protocol to communicate with the rest of the PacketCable network.

• Gate controller (GC)—A server that controls the establishment of gates in the PacketCable network. A gate is a logical entity in the CMTS that ensures that a service flow is authorized for the QoS features it is requesting. A separate gate controls the upstream and downstream directions of a service flow. When a call is established, the GC instructs the CMTS to create each gate and supplies the set of authorized parameters for each gate, which the CMTS uses to authorize the QoS requests that the MTA is making for the call. The GC is also responsible for coordinating the creation of the two sets of gates at each end of the call so that the call can be authorized and established.

Note	A PacketCable network can contain multiple GCs, although only one server at a time is in control of any particular call. Typically, the same workstation provides both the CMS and GC servers.

• Record keeping server (RKS)—Billing server that collects the information about each call as it is made. The RKS uses the Remote Authentication Dial-In User Service (RADIUS) protocol to collect the billing data from the CMTS and other PacketCable servers. The RKS generates a call data record (CDR) for every call and forwards that information to the appropriate application server at the service provider’s data processing center for further processing.

A key feature of a PacketCable network is a dynamic quality of service (DQoS) capability that is similar to the dynamic services provided by DOCSIS 1.1. However, DOCSIS 1.1 DQoS authorizes and provisions services only in the cable network and does not reserve the resources needed to propagate a call from one endpoint to another across the network.

The PacketCable DQoS extends the DOCSIS 1.1 services across the entire network, so that resources can be dynamically authorized and provisioned from one endpoint to another. This prevents possible theft-of-service attacks and guarantees customers the services they are authorized to use.

Note	PacketCable 1.0 requires that DOCSIS 1.1 be used for resource reservation within the cable network for E-MTA clients.

DOCSIS 2.0 mandates unique Transaction IDs (TAIDs) across transactions. The TAIDs must be unique and not incremented. The TAIDs are assigned by the senders and sometimes the TAID timeout is mismatched between senders and receivers. This affects the uniqueness of the TAID.

A TAID can be reused when the sender finishes a transaction. Similarly, DOCSIS allows the receiver to identify a transaction by TAID without the SFID. Problems arise in DSD transaction and DSA/DSC interrupted transactions, when these two requirements are combined.

The uniqueness of TAID must be ensured to resolve the interoperability issue. This is done by making the CMTS wait until T10 to reuse the same TAID. A new TAID allocation algorithm is used to fulfill this requirement.

It creates a TAID pool to replace the existing 16-bit counter. This TAID pool is monitored by timers to track the TAID expiration. A flag is assigned to each TAID in the pool to indicate its availability. When new TAID is requested, the dynamic service process checks the availability of the TAID. If the TAID is available, it is allocated to the new service flow, else the request is rejected.

Once the TAID is allocated, the timer starts with T10 expiration time and the TAID flag is set to FALSE to indicate the unavailability of TAID. The dynamic service process keeps track of the timer. When the time expires, the timer stops and the flag is set to TRUE to indicate the availability of TAID.

The TAID pool is allocated and initialized at the process initialization. All timers associated with the TAIDs are added as leaf timers to the process' parent timer.

The PacketCable Subscriber ID feature adds a subscriber ID to all Gate Control messages and enhances error codes returned from the Cisco CMTS router.

Previously, the Gate ID was unique only to individual CMTS systems, with the CMTS proxying all CMS Gate Control messaging through a central device, which manages the CMTS connections on behalf of the CMS. The CMS had a single Common Open Policy Service (COPS) association to the proxy device. Therefore, the Gate IDs could be duplicated when using multiple CMTS systems.

A subscriber ID is added to each Gate Control message to disambiguate the Gate IDs between the CMS and proxy device. The subscriber ID parameter is added to the following COPS messages:

• GATE-INFO
• GATE-DELETE
• GATE-OPEN
• GATE-CLOSE

The subscriber ID is available at the CMS and is used in the Gate-Set messages. Additionally, the error codes returned from CMTS or its proxy are enhanced to include more specific information about gate operation failures.

To enable this feature, use the packetcable gate send-subscriberID command in global configuration mode.

The PacketCable feature offers the following benefits to service providers and their customers:

Router> enable 

Router# configure terminal

Router(config)# aaa new-model 

Router(config)# aaa group server radius packetcable 

Router(config-sg-radius)# server radius-server1 

Router(config-sg-radius)# exit 

Router(config)# aaa accounting network default start-stop group radius group packetcable 

Router(config)# radius-server host radius-server1 key 0000000000000000 

Router(config)# radius-server vsa send accounting 

Router(config)# exit 

Troubleshooting Tips

If the connection between a PacketCable CMS and the Cisco CMTS router is not completely established, and the PacketCable CMS does not correctly terminate the session by sending a TCP FIN message, the connection shows a COPS server in the output of the show cops server command.

Router> enable

Router# configure terminal

Router(config)# packetcable timer T0 300000

Router(config)# packetcable timer T1 400000

Router(config)# packetcable timer multimedia T1 400000

Router(config)# end

Troubleshooting Tips

If the connection between a PacketCable CMS and the Cisco CMTS router is not completely established, and the PacketCable CMS does not correctly terminate the session by sending a TCP FIN message, the connection shows a COPS server in the output of the show cops server command.

This section provides a few examples to illustrate how you can use the show cable calls and show cable modem calls commands to verify different scenarios associated with Emergency 911 calls.

The following example displays Emergency 911 calls made on the Cable8/1/1 interface on the Cisco CMTS router during the window set for high priority calls:

Router# show cable calls
Interface   ActiveHiPriCalls  ActiveAllCalls  PostHiPriCallCMs  RecentHiPriCMs
C5/0/0  				0                 0               0                 0              
C5/0/1  				0                 0               0                 0              
C5/1/0  				0                 0               0                 0              
C5/1/1  				0                 0               0                 0              
C5/1/2  				0                 0               0                 0              
C5/1/3  				0                 0               0                 0              
C5/1/4  				0                 0               0                 0              
C6/0/0  				0                 0               0                 0              
C6/0/1  				0                 0               0                 0              
C7/0/0  				0                 0               0                 0              
C7/0/1  				0                 0               0                 0              
C8/1/0  				0                 0               0                 0              
C8/1/1  				1                 1               0                 0              
C8/1/2  				0                 0               0                 0              
C8/1/3  				0                 0               0                 0              
C8/1/4  				0                 0               0                 0              
Total       1                 1               0                 0              

The following example displays the change on the Cisco CMTS router when this Emergency 911 calls ends:

Router# show cable calls
Interface   ActiveHiPriCalls  ActiveAllCalls  PostHiPriCallCMs  RecentHiPriCMs
C5/0/0  				0                 0               0                 0              
C5/0/1  				0                 0               0                 0              
C5/1/0  				0                 0               0                 0              
C5/1/1  				0                 0               0                 0              
C5/1/2  				0                 0               0                 0              
C5/1/3  				0                 0               0                 0              
C5/1/4  				0                 0               0                 0              
C6/0/0  				0                 0               0                 0              
C6/0/1  				0                 0               0                 0              
C7/0/0  				0                 0               0                 0              
C7/0/1  				0                 0               0                 0              
C8/1/0  				0                 0               0                 0              
C8/1/1 				 0                 0               0                 1              
C8/1/2  				0                 0               0                 0              
C8/1/3  				0                 0               0                 0              
C8/1/4  				0                 0               0                 0              
Total       0                 0               0                 1              

The following example displays information that is available when making a voice call from the same MTA to another MTA on the same interface:

Router# show cable calls
Interface   ActiveHiPriCalls  ActiveAllCalls  PostHiPriCallCMs  RecentHiPriCMs
C5/0/0  				0                 0               0                 0              
C5/0/1  				0                 0               0                 0              
C5/1/0  				0                 0               0                 0              
C5/1/1  				0                 0               0                 0              
C5/1/2  				0                 0               0                 0              
C5/1/3  				0                 0               0                 0              
C5/1/4  				0                 0               0                 0              
C6/0/0  				0                 0               0                 0              
C6/0/1  				0                 0               0                 0              
C7/0/0  				0                 0               0                 0              
C7/0/1  				0                 0               0                 0              
C8/1/0  				0                 0               0                 0              
C8/1/1  				0                 2               1                 1              
C8/1/2  				0                 0               0                 0              
C8/1/3  				0                 0               0                 0              
C8/1/4  				0                 0               0                 0              
Total       0                 2               1                 1              

The following example displays information that is available when a voice call from the same MTA to another MTA on the same interface ends:

Router# show cable calls
Interface   ActiveHiPriCalls  ActiveAllCalls  PostHiPriCallCMs  RecentHiPriCMs
C5/0/0  				0                 0               0                 0              
C5/0/1  				0                 0               0                 0              
C5/1/0  				0                 0               0                 0              
C5/1/1  				0                 0               0                 0              
C5/1/2  				0                 0               0                 0              
C5/1/3  				0                 0               0                 0              
C5/1/4  				0                 0               0                 0              
C6/0/0  				0                 0               0                 0              
C6/0/1  				0                 0               0                 0              
C7/0/0  				0                 0               0                 0              
C7/0/1  				0                 0               0                 0              
C8/1/0  				0                 0               0                 0              
C8/1/1  				0                 0               0                 1              
C8/1/2  				0                 0               0                 0              
C8/1/3 				 0                 0               0                 0              
C8/1/4  				0                 0               0                 0              
Total       0                 0               0                 1              

The following examples display the show cable modem calls command output on the Cisco CMTS router over a period of time, with changing call status information. The call information disappears when a call ends.

Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)
0000.cab7.7b04 10.10.155.38    C8/1/1/U0 18    R                   0:39
Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)

The following example displays a new Emergency 911 call on the Cisco CMTS router:

Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)
0000.cab7.7b04 10.10.155.38    C8/1/1/U0 18    HV                  1:30

The following example displays the end of the Emergency 911 call on the Cisco CMTS router:

Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)
0000.cab7.7b04 10.10.155.38    C8/1/1/U0 18    R                   0:3 

The following example displays a non-emergency voice call on the Cisco CMTS router from the same MTA:

Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)
0000.ca36.f97d 10.10.155.25    C8/1/1/U0 5     V                    -
0000.cab7.7b04 10.10.155.38    C8/1/1/U0 18    RV                  0:30

The following example displays the end of the non-emergency voice call on the Cisco CMTS router:

Router# show cable modem calls
Cable Modem Call Status Flags:
H: Active high priority calls
R: Recent high priority calls
V: Active voice calls (including high priority)
MAC Address    IP Address      I/F       Prim  CMCallStatus  LatestHiPriCall
                                         Sid                    (min:sec)
0000.cab7.7b04 10.10.155.38    C8/1/1/U0 18    R                   0:36

The following network components are required to support the PCMM feature:

• Application Server—Responsible for relaying client requests to the Application Manager.
• Application Manager—Responsible for application or session-level state and for applying session control domain (SCD) policy.
• Policy Server—Responsible for applying the RCD policy and for managing relationships between the Application Manager and a Cisco CMTS router.
• Cisco CMTS router—Responsible for performing admission control and managing network resources through DOCSIS service flows.

Figure below provides an architectural overview of the PCMM functionality:

Figure 1. PCMM Architectural Overview

• PCMM Gate Overview and PCMM Dynamic Quality of Service
• PCMM Persistent Gate

The following tasks describe how to enable PCMM operations and configure its related features on the Cisco CMTS router:

The following sections provide configuration examples for PCMM operations on the Cisco CMTS router:

Enhanced high availability support enables the synchronization of PacketCable and PacketCable MultiMedia (PCMM) gates during switchover events on the Cisco CMTS router. This enhancement is enabled by default.

This functionality uses the existing per-interface HCCP commands that are used to associate the working and protect interfaces in the case of N+1 redundancy.

The multiple grants per interval (MGPI) feature enables the Cisco CMTS router to map multiple PacketCable Multimedia gates (application flows) to a single DOCSIS service flow using UGS traffic profiles of the same cable modem. In other words, the Cisco CMTS router increases the number of grants per interval for each application flow based on a single service flow, resulting in multiple grants per interval.

The MGPI feature supports the flow-aggregated voice MGPI functionality based on CableLabs PacketCable Specification (PKT-SP-MM-I05-091029). The flow-aggregated MGPI functionality allows the application manager to use the UGS traffic profile to explicitly set the number of grants per interval and place several application flows on a single gate. This results in an aggregated view for event messages, volume, and time usage limits.