Cisco 7600 Series Router SIP, SSC, and SPA Software Configuration Guide

Specifying the Interface Address on a SPA

Four CEoP SPAs can be installed in a SPA interface processor (SIP). Ports are numbered from left to right, beginning with 0. Single-port SPAs use only the port number 0. To configure or monitor SPA interfaces, you need to specify the physical location of the SIP, SPA, and interface in the command-line-interface (CLI). The interface address format is slot / subslot / port, where:

• slot —Specifies the chassis slot number in the Cisco 7600 series router where the SIP is installed
• subslot —Specifies the secondary slot of the SIP where the SPA is installed
• port —Specifies the number of the individual interface port on a SPA

The following example shows how to specify the first interface (0) on a SPA installed in subslot 1 of the SIP in chassis slot 3:

For more information about how to identify slots and subslots, see the “Identifying Slots and Subslots for SIPs, SSCs, and SPAs” section.

Configuring Port Usage (Overview)

The 24-Port Channelized T1/E1 ATM CEoP SPA and 1-Port Channelized OC-3 STM1 ATM CEoP SPA can be configured to run in the following modes:

• Circuit emulation (CEM)
• Channelized Asynchronous Transfer Mode (ATM)
• Inverse Multiplexing over ATM (IMA)

The 2-Port Channelized T3/E3 ATM CEoP SPA, introduced in Cisco IOS Release 12.2(33)SRC, can be configured to run in ATM mode. The SPA does not currently support CEM or IMA mode.

The following tables show the commands to configure each of the SPAs for CEM or ATM. Detailed configuration instructions are provided in the sections that follow.

Configuring the 24-Port Channelized T1/E1 ATM CEoP SPA

To configure the 24-Port Channelized T1/E1 ATM CEoP SPA, perform the following steps:

Configuring the 2-Port Channelized T3/E3 ATM CEoP SPA

To configure the 2-Port Channelized T3/E3 ATM CEoP SPA, complete these steps:

SUMMARY STEPS

Step 1 enable

Step 2 configure terminal

Step 3 card type {t3 | e3 } slot subslot

Step 4 controller { t3 | e3 } slot/subslot/port

Step 5 channelized mode {t1 | e1}

Step 6 cem-group group unframed

or

{t1 } 1-28 cem-group group timeslots 1-24

{e1 } 1-21 cem-group group timeslots 1-31

or

atm

or

{t1 } 1-28 ima-group group-number

{e1 } 1-21 ima-group group-number

Step 7 exit

DETAILED STEPS

Note See “Configuring T3” section for information about the features that are not supported on the CEoP SPA in Cisco IOS Release 12.2SRC.

Restrictions and Usage Guidelines

Follow these restrictions and usage guidelines while configuring 2-Port Channelized T3/E3 CEoP SPA:

• CEoP SPAs does not support Layer 3QoS.
• Bridging featues such as bridging routed encapsulations (BRE), multipoint bridging(MPB), routed bridge encapsulation(RBE), and multi VLAN are not supported on CEoP.
• E3 Channelization to E1 is not supported.
• Maintenance Digital Link (MDL) is supported only for DSX3-C bit framing.
• CEoP SPAs simultaneously supports multiple interface types.
• Adaptive clock recovery is supported on 2-Port Channelized T3/E3 CEoP SPA.
• Out-of-Band(OOB) clock recovery for CEM is not supported.
• E3 or T3 ATM is not supported.

Sample Configuration for 2-Port Channelized T3/E3 CEoP SPA on Clear channel T3

Configure SPA in a T3 mode

Create an T3 ATM interface

Create CEM group

Sample Configuration for 2-Port Channelized T3/E3 CEoP SPA on Clear channel E3 mode

Configure SPA in a E3 mode

Create an E3 ATM interface

Create CEM group

Router(config-controller)# cem-group 0 unframed

Sample Configuration for 2-Port Channelized T3/E3 CEoP SPA on CT3-T1 Channelization mode

Configure SPA in a T3 mode

Create an T3 ATM interface

Router(config-controller)# t1 1 atm

Create a NxDS0 T1 CEM group

router(config-controller)# t1 2 cem-group 0 timeslots 1-12

Create two IMA groups (1 with two T1 members)

Sample Configuration for 2-Port Channelized T3/E3 CEoP SPA on CT3-E1 Channelization mode

Configure SPA in a T3 mode

Changing channelization to E1

Create an E1 ATM interface

Create a NxDS0 E1 CEM group

Create two IMA groups (1 with two E1 members)

Verifying 2-Port Channelized T3/E3 CEoP SPA configuration

None

Note See the “Configuring T3” section for information about the features that are not supported on the SPA in Cisco IOS Release 12.2SRC.

Configuring the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SONET VT1.5

To configure the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SONET VT 1.5, perform the following steps:

Configuring the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SDH AU-4 C-12

To configure the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SDH AU-4 C-12, perform the following steps:

Configuring the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SDH AU-3 C-11

To configure the 1-Port Channelized OC-3 STM1 ATM CEoP SPA for SDH AU-3 C-11, perform the following steps:

Configuration Guidelines and Restrictions

Not all combinations of payload-size and dejitter-buffer size are supported. Payload size, or dejitter configurations are rejected at the CLI level in CEM circuit mode on the SPA if they are not compatible. Any incompatible parameter modifications will be rejected and the configuration will fall back to the old dejitter and payload parameters if the parameters are being applied through the cem class template.

For relation between the payload size and the dejitter buffer size on CeoPSN and SaToP T1/E1 frames see Table 10-1 , CESoPSN DS0 Lines: Payload and Jitter Limits , Table 10-3 , SAToP T1 Frame: Payload and Jitter Limits and Table 10-4 , SAToP E1 Frame: Payload and Jitter Limits .

Configuring a CEM Group

To configure a CEM group to represent a CEM circuit on a SPA port, use the following procedure.

Note ● The first cem-group command under the controller creates a CEM interface that has the same slot/subslot/port information as the controller. The CEM interface is removed when all of the CEM groups under the interface have been deleted.

• The CEM interface is always up, even if the controller state is down. This allows the CEM pseudowire to carry alarm information to the remote end.

Configuring a CEM Class (Optional)

To assign CEM parameters to one or more CEM interfaces, you can create a CEM class (template) that defines the parameters and then apply the class to the interfaces.

CEM class parameters can be configured directly on the CEM circuit. The inheritance is as follows:

• CEM circuit (highest level)
• Class attached to CEM circuit
• Class attached to the CEM interface

If the same parameter is configured on the CEM interface and CEM circuit, the value on the CEM circuit takes precedence.

To configure a CEM class, use the following procedure:

In the following example, a CEM class (TDM-Class-A) is configured to set the payload-size and dejitter-buffer parameters:

In the next example, the CEM parameter settings from TDM-Class-A are applied to CEM interface 2/1/0. Any CEM circuits created under this interface inherit these parameter settings.

Configuring a CEM Pseudowire

To configure a pseudowire to transport a CEM circuit across the MPLS network, follow this procedure.

To configure a pseudowire to transport a CEM circuit across the UDP/IP network, follow this procedure.

For troubleshooting CEMoUDP issues, see the Overview of the CEoP and Channelized ATM SPAs section.

For troubleshooting ACR issues, see the Configuring Access Circuit Redundancy on CEoP and ATM SPAs section under Configuring the CEoP and Channelized ATM SPAs.

Note When the T1 controller that carries a particular CEM circuit traffic goes down, a message is sent about a failure between PE and CE routers. This results in pseudowire status as down, but the data plane is kept up for the alarms to be carried over.

The following sample configuration shows a T1 port on which two CEM circuits (groups) are configured. Each CEM circuit carries data from time slots of the TDM circuit attached to the port.

The two xconnect commands create pseudowires to carry the TDM data across the MPLS network. Pseudowire 2 carries the data from time slots 1, 2, 3, 4, 9, and 10 to the remote PE router at 10.10.10.10. Pseudowire 5 carries the data in time slots 5, 6, 7, 8, and 11 to the remote PE router at 10.10.10.11.

The following sample configuration for CEM over UDP, shows one E1 port on which two CEM circuits (groups) are configured. Each CEM circuit carries data from time slots of the TDM circuit attached to the port. Loopback 22 is mapped to the ACR group 1.

The two xconnect commands create pseudowires to carry the TDM data across the IP network. Pseudowire 1 carries data from time slots 1, 2, 3, 4, 5 and 6 to the remote PE router at 12.12.12.12. Pseudowire 2 carries data in time slots 1-31 to the remote PE router at 12.12.12.12.

Configuring TDM Local Switching

TDM Local Switching allows switching of Layer 2 data between two CEM interfaces on the same router. The two CEM groups can be on the same physical interface or different physical interfaces; they can be on the same SPA, the same line card, or different line cards.

Note For Cisco IOS Release 12.2(33)SRC, this feature is supported on the 24-Port Channelized T1/E1 ATM CEoP SPA and the 1-Port Channelized OC-3 STM1 ATM CEoP SPA.

Use the following guidelines for CEoP Phase 2 TDM Local Switching:

• Autoprovisioning is not supported.
• Out-of-band signaling is not supported.
• Port mode local switching is not supported on the CEM interface.
• Interworking with other interface types is not supported.
• The same CEM circuit cannot be used for both local switching and xconnect.
• You can use CEM local switching between two CEM circuits on the same CEM interface.
• CEM local switching can be across a 24-Port Channelized T1/E1 ATM CEoP SPA and a 1-Port Channelized OC-3 STM1 ATM CEoP SPA.

Use the following procedure to configure CEoPS Phase 2 TDM Local Switching:

Configuration Example

The following is an example:

Verifying

Use the show connection, show connection all, show connection id conn id, and show connection conn name commands to verify.

Local Switching Redundancy

Local Switching Redundancy provides a backup attachment circuit (AC) when the primary attachment circuit fails. All the ACs must be on same Cisco 7600 series router.

Note For Cisco IOS Release 12.2(33)SRC, this feature is supported on the 24-Port Channelized T1/E1 ATM CEoP SPA and the 1-Port Channelized OC-3 STM1 ATM CEoP SPA, as well as the 2-Port and 4-Port OC-3c/STM-1 ATM SPA, the 1-Port OC-12c/STM-4 ATM SPA, and the 1-Port OC-48c/STM-16 ATM SPA.

The following combinations of CEM ACs are supported:

• CEM ACs on the same SPA
• CEM ACs on different SPAs on the same SIP
• CEM ACs on different SIPs on the same Cisco 7600 series router

Guidelines

Local Switching Redundancy guidelines are as follows:

• Autoconfiguration of CEM interfaces is not supported.
• Only the tail end AC can be backed up, if head end fails, there is no protection.
• The circuit type of the primary and backup AC must be identical (failover operation will not switch between different types of interfaces or different CEM circuit types).
• Backs up a local switching connection to cem-ckt3 of CEM interface cem3.Only one backup AC is allowed for each connection.
• Autoconfiguration of backup CEM circuits is not allowed. Autoconfiguration is allowed for backup ATM Permanent Virtual Circuits (PVCs) or ATM Permanent Virtual Paths (PVPs).
• The CEM circuit used as a backup in a local switching connection cannot be used for xconnect configurations.
• Dynamic modification of parameters in a local switching connection is not supported in the case where the tail-end segment is backed up to a segment using the backup command. If you want to modify the parameters in any of the three segments (head-end, tail-end, or backup segment), you must first unconfigure with the backup command, make the changes in the individual segments, and then reconfigure the backup with the backup command.

Configuration

Configuration Example

The following is a configuration example for Local Switching Redundancy:

Verifying

Use the show xconnect all command to check the status of the backup and primary circuits.

Configuring VC QoS on VP-PW CEoP SPAs

The SIPs and SPAs support many QoS features using modular QoS CLI (MQC) configuration. For configuration information on Modular QoS CLI (MQC) policy support and ATM VCI (match atm-vci command), see the “Configuring QoS Features on a SIP” section of Chapter5, “Configuring the SIPs and SSC”

Restriction

VC QoS on VP-PW feature works only with Single Cell Relay and does not work with Packed Cell Relay.

Configuring an ATM Pseudowire

To configure a pseudowire for an ATM connection or an IMA link bundle, perform these steps. The pseudowire is used to carry the ATM data across the MPLS network.

T3 Configuration Guidelines

This section lists the guidelines for configuring the 2-Port Channelized T3/E3 ATM CEoP SPA. For information about supported features, see Chapter10, “Overview of the CEoP and Channelized ATM SPAs”

Note For a list of features that are not supported in Cisco IOS Release 12.2SRC, see the “Unsupported Features” section.

T3 Mode

In clear-channel T3 mode, each SPA port provides a single high-speed data channel operating at 44210 kilobits per second (kbps).

ATM Mode

For ATM mode up to 4000 point-to-point ATM VCs (per SIP) are supported.

Configuring Port Usage

Perform the following steps to configure a SPA port for T3:

Note E3 is not supported with Cisco IOS Release 12.2(33)SRC.

Configuring the SPA for Clear-Channel ATM

To configure a T3/E3 SPA port for clear-channel ATM, follow these steps:

SONET Controller Configuration

To configure the SONET controller, perform this task:

SDH Configuration for AU-4 C-12

This section describes how to enable an interface under SDH framing with AU-4 mapping after configuring the SONET controller.

SDH Configuration for AU-3 C-11

This section describes how to enable an interface under SDH framing with AU-3 mapping after configuring the SONET controller.

IMA Configuration Guidelines

Follow these guidelines as you configure the CEoP SPA for inverse multiplexing ATM:

• IMA is supported on the Cisco 7600 SIP-400 with the following CEoP SPAs:

– 24-Port Channelized T1/E1 ATM CEoP SPA (24 IMA groups per SPA)

– 1-Port Channelized OC-3 STM1 ATM CEoP SPA (42 IMA groups per SPA)

– 2-Port T3/E3 ATM CEoP SPA (42 IMA groups per SPA)

• When a T1 or E1 interface is configured for IMA mode, the interface no longer operates as an individual ATM link.
• IMA group numbers (IDs) must be unique on the SPA.
• You cannot mix T1 and E1 lines in the same IMA group.
• The T1 or E1 lines in an IMA group must be on the same CEoP SPA. An IMA group cannot contain T1 or E1 lines from different SPAs.
• Both ends of the T1 or E1 link must be in IMA mode.
• IMA is compliant with nonstop forwarding with stateful switchover (NSF/SSO). This means that when a switchover occurs, IMA connections remain up and continue to pass traffic, with no interruption in service.
• IMA Control Protocol (ICP) cells and filler cells are discarded by the receiving end; therefore, any counters displayed in show command output do not include these cells.
• The Cisco 7600 SIP-400 supports a maximum transmission unit (MTU) size of 4470 bytes.

To ensure that IMA groups synchronize correctly after a restart, observe the following guidelines as you configure IMA links. For information about restarts, see the description of ima autorestart in the “Configuring IMA Group Parameters” section.

• Each end of an IMA link should have a different IMA group ID. This way, after a restart the router can detect links in loopback mode, which means that a link is communicating with itself instead of the remote end. When both ends of a link have the same group ID, the link is in loopback mode.
• If both ends of an IMA link have the same group ID, loopbacked links might be the first to respond after a restart, in which case the IMA group could be communicating with itself instead of the far end.
• Effective from Cisco IOS release 15.1(01)S, the number of IMA groups supported on the different flavours of the CEoP SPA are:

– 24 T1/E1/J1 port SPA (12 IMA groups per SPA)

– 2XT3/E3 port SPA (42 IMA groups per SPA)

– 1xOC3 port SPA (42 IMA groups per SPA)

• When the atm bandwidth dynamic command is enabled, all of the permanent virtual circuits (PVCs) configured on an IMA group interface are re-created if the total available IMA group bandwidth changes.
• Maximum of 16 links can be configured on an IMA group.

IMA Link Bundle Configuration Overview

You bundle T1 or E1 links together by assigning the links to the same IMA group and configuring a PVC for the links in the group to use.

To assign a T1 or E1 link to an IMA group, issue the ima group group-number command under the T1 or E1 controller for the port that the link is attached to. Bundle a set of links together by issuing ima group under the controller for each of the links that you want to add to the bundle, and specify the same group number for each.

The router creates an IMA interface to represent the IMA group (link bundle). The interface has the same slot/subslot information as the SPA, followed by the IMA group ID, as shown here (for example, atm2/1/ima0):

interface atm slot / subslot / ima group-id

The IMA interface has all of the characteristics of an ATM interface and supports any currently supported ATM features.

When all of the T1/E1 interfaces are removed from an IMA group, the IMA interface that represents the group is removed.

To configure the IMA group for operation, you must:

• Configure a PVC for the links in the IMA group to use.
• Define the operating characteristics of the IMA link bundle by configuring IMA group parameters. (See the “Configuring IMA Group Parameters” section.)

Configuration Example

The following steps provide an example of the steps to configure an IMA link bundle on the 24-Port Channelized T1/E1 ATM CEoP SPA. Detailed steps are provided in the section that follows.

1. Bundle T1 or E1 links together by creating an IMA group and adding each link to the group. In this example, the T1 links attached to ports 0, 1, and 2 of the CEoP SPA in chassis slot 2, SPA subslot 1, are assigned to the same IMA link bundle (IMA group 0). Likewise, the E1 links attached to ports 0 and 1 of the SPA in chassis slot 5, SPA subslot 1 are assigned to another bundle (IMA group 1).

2. Configure a PVC and MPLS pseudowire for the links in the IMA group to use. In the following example, PVC 0/100 is configured for the T1 links in IMA group 0 and PVC 0/101 is configured for the E1 links in IMA group 1:

3. Configure IMA group parameters to define how the links in the group are to operate. In the following example, IMA group 0 is being configured to operate with a minimum of 2 active links, independent clock mode, and a frame length of 256:

Configuring an IMA Link Bundle

To configure an IMA link bundle on a 24-Port Channelized T1/E1 ATM CEoP SPA, perform the following steps from global configuration mode:

Configuring IMA Group Parameters

Use the commands in Table 11-2 to configure parameters for an IMA group. Issue the commands in interface configuration mode under the IMA interface of the IMA group being configured. Use the no form of each command to turn off a feature or to revert to its default setting.

Note If you modify parameters on an IMA interface, the interface is automatically restarted.

Verifying the IMA Configuration

To display information about all configured IMA groups, or a specific group, use the show ima interface command in privileged EXEC mode:

show ima interface atm slot / subslot / ima group-number [ detail ]

In the following example, information is displayed for IMA group 1 (on the SPA in slot 5, subslot 0):

IMA Auto Restart Examples

IMA auto restart is disabled by default, which means that IMA learns the ID of the remote IMA group each time a restart occurs. To see the current settings for auto restart, issue the show ima interface command and view the Auto-Restart section of the command output.

Following are several examples of different ways to enable auto restart:

• To enable auto restart so that the local IMA group synchronizes with the first remote IMA group that becomes active, issue the command as follows (where near-end-group-id identifies the local IMA group). The learned remote group ID remains active until the SPA is reloaded.

• To specify which remote IMA group the local IMA group should sync up with, issue the command as follows (where near-end-group-id identifies the local IMA group and far-end-group-id identifies the remote IMA group). Both near-end and far-end IDs must be the same.

• To disable auto restart and have IMA learn the remote IMA group ID after each restart, issue the command as follows:

BITS Clock Support—Receive and Distribute—CEoP SPA on SIP-400

You can use the BITS Clock Support—Receive and Distribute—CEoP SPA on SIP-400 feature to select and configure a clock and distribute it across the chassis to be used as the Transmit reference on all SPA ports.

The BITS Clock support - Receive and Distribute - CEoP SPA on SIP-400 feature is supported on Cisco IOS Release 12.2SRB on the SPA-24CHT1-CE-ATM and the SPA-1CHOC3-CE-ATM, SPA-4XOC3 ATM, SPA-1xOC12/STM4 POS SPAs.

The line card operates in three different modes, dependiing on the configuration and the configured source state.

• Free-running—A line card that is not participating in network-clocking or a line card that is actively sourcing the clock operates in free-running mode. In this mode, the line card internal oscillator generates the reference clock to the backplane.

Note In a nonpartcipating mode or a disabled mode, the line card distributes a Stratum 3-quality timing signal to an external reference clock. Other interfaces on different line cards receive either the backplane reference clock or the external reference clock depending on their configurations.

• Normal—In normal mode, the module synchronizes with an externally supplied network timing reference, sourced from one of the chassis BITS inputs or recovered from a network interface. In this mode, the accuracy and stability of the output signal is determined by the accuracy and stability of the input reference.

Note Line card operation is in free-running mode only if the SIP-400 is configured as the active sources; otherwise the line cards operate in normal mode.

• Holdover—In holdover mode, the network timing module generates a timing signal based on the stored timing reference used when operating in normal mode. Holdover mode is automatically selected when the recovered reference is lost or has drifted excessivley.

Note You cannot configure the drift range; it is set internally on the line card to +/-9.2 phase shifts per minute (ppm) by default.

Note All line cards operate in the free-running mode until network clock is configured.

Guidelines

Use the following guidelines:

• The SIP-400 operates in free-running mode until network clock is configured.
• When the network clocking configuration is present in the startup configuration, the clocking configuration is not applied until five minutes after the configuration has been parsed. This prevents clocking instability on the backplane when the interfaces/controllers come up out of order.
• Network clocking is enabled by default for the SIP-400.
• Cisco IOS Release 12.2SRB does not support local network clock configurations or synchronization status messaging (SSM).
• If there is a source flap, there is an interval of 180 seconds before the source becomes valid and active.
• In the event of an Out-of-Range (OOR) switchover (revertive mode), the source switchover occurs when the clock offset crosses the -9.2 ppm or +9.2 ppm threshold. If this occurs, you must reconfigure the source.

Configuration Tasks

To configure Network Clocking for the Cisco 7600/SIP-400, use the following commands:

Verifying

Use the show platform hardware network-clocks command to verify.

Configuring Clock Recovery

When configuring clock recovery, consider the following guidelines:

Adaptive Clock Recovery

• Clock source:

– In Cisco IOS Release 12.2(33)SRC and later, both the 1-Port Channelized OC-3 STM1 ATM CEoP SPA and the 24-Port Channelized T1/E1 ATM CEoP SPA can be used as a clock source.

– In earlier releases, only the 24-Port Channelized T1/E1 ATM CEoP SPA can be a clock source.

– Effective from Cisco IOS Release 15.1(1)S release, 2XT3E3 CE/ATM SPA supports adaptive clock recovery for T3/E3 CEM. Out of Band (OOB) Clocking for T3/E3 CEM is not supported due to lack of hardware support.

• Number of clock sources allowed:

– In Cisco IOS Release 12.2(33)SRC and later, multiple clocks can be sourced for the router: one clock for each SPA.

– In earlier releases, only a single clock can be sourced for a router.

• The clock must be the same as used by the router as the network clock. Any pseudowire in this case can carry the clock.
• The minimum bundle size of CEM pseudowires on the network that delivers robust clock recovery is 4 DS0s.
• The minimum packet size of CEM pseudowires on the network that delivers robust clock recovery is 64 bytes.

Differential Clocking

• The maximum number of differential clocks sourced from a 24-Port Channelized T1/E1 ATM CEoP SPA is 24.
• The 24-Port Channelized T1/E1 ATM CEoP SPA can recover up to 24 T1/E1 clocks.
• There are several bundles sent from the same port. The bundle that is used for carryingthe clock of the port is the first created bundle of the port. Only pseudowires that include the first DS0 of a port can carry differential clock.

To configure clock recovery on a 24-Port Channelized T1/E1 ATM CEoP SPA, use the following procedure:

To apply the recovered clock to the controller, use the following procedure:

Verifying Clock Recovery

To verify clock recovery, use the show recovered-clock command. In Cisco IOS Release 12.2SRB1 and later, command output has been expanded to include the port number and CEM group number.

Use the show platform network-clock command to display the contents of network clocking registers.

Configuring Out-of-Band Clocking

A TDM network requires a synchronized clock at each end of the connection (the source and destination). This means that the source and destination clock signals must be synchronized to each other in order to maintain data integrity on the communication link.

On the other hand, a packet-switched network (PSN) does not use a clocking strategy, which means that the PSN does not provide frequency synchronization between source and destination routers. Therefore, to transmit TDM data across a PSN (such as an MPLS network), we need a way to deliver the clocking signal between the source and destination routers.

Out-of-band clocking provides a way to deliver a clock signal between two CEoP SPAs, which allows TDM devices connected to the SPAs to communicate with each other. Dedicated pseudowires (called out-of-band clock channels) carry the timing signal between the sending and receiving SPAs. When a TDM device sends data to a destination TDM device, the receiving SPA uses the out-of-band clock channel to recover the clock signal that was used to send the data.

By keeping the timing packets separate from data packets, out-of-band clocking delivers an extremely accurate timing signal. This timing accuracy is important for mobile wireless applications and other specialized applications that have very low tolerances for such things as packet delay variation (PDV), jitter, and latency in the network. In-band clocking (where timing information is derived from the data stream) does not provide a clock that is accurate enough for these applications.

To set up out-of-band clock channels, you must configure a master clock interface and a slave clock interface on the SPAs and configure pseudowires to connect the master and slave clocks. Instructions for performing these steps are provided later in this section.

Benefits

Out-of-band clocking provides the following benefits:

• Enables mobile wireless providers to migrate from TDM networks to PSNs in order to save on costs and improve scalability.
• CEoP equipment can ignore the contents of the timing packets that are sent over the out-of-band clock channel because the packets do not contain data.
• Allows the CEoP SPA to be used for applications that use something other than constant bit rate (CBR) data. For example, out-of-band clocking allows the SPA to be used for 3G (data) wireless applications, which use AAL2 in variable bit rate (VBR) mode. In addition, out-of-band clocking allows the SPA to be used for 2G (voice) applications.
• Provides recovered clock accuracy that complies with ITU-T specifications G.823 and G.824, which enables the CEoP SPA to be used in mobile and wireless applications (including voice) that require extreme synchronization accuracy.
• Provides an alternative clock-recovery mechanism when adaptive clocking cannot be deployed.
• Enables the CEoP SPA to be the master clock in a PSN.
• Makes it possible to have two master clocks. Previously, only one master clock was possible.

Configuration Guidelines

The following guidelines apply to out-of-band clocking on CEoP SPAs:

• The default packet size for out-of-band clock channels (CEM circuits) is 910 bytes.
• Out-of-band clocking can co-exist with Stateful SwitchOver (SSO), but it is not SSO compliant. Therefore, if a switchover occurs, the out-of-band clocking functionality is not available for a brief period of time while the feature is brought back online.
• A CEoP SPA cannot be configured as both a master and slave clock. To reconfigure a SPA’s clock type, you must first remove the existing clock configuration (master or slave).
• Pseudowires for out-of-band clocking are configured under the virtual CEM interface that represents the recovered clock interface. This process differs from normal CEM pseudowires, which are configured under the port (controller interface).
  When no network clock is available, the virtual CEM interface goes down and the pseudowire is disabled. This process is reversed when a valid network clock becomes available again. Normal CEM interfaces never go down, even if the associated physical link is down.
• The master clock pseudowire and slave clock pseudowire should be on different CEoP SPAs.

Router Sending Clock (Master Clock)

• You must select the common telecom 19.44MHz clock as the recovered clock to use for the master clock.
• A maximum of 64 out-of-band clock channels can be configured from the CEoP SPA that provides the master clock signal.
• The out-of-band clock channel (pseudowire) is configured under the virtual CEM interface that represents the SPA from which the master clock is recovered. The xconnect command used to create the clock channel must specify the destination for the clock signal.
• The out-of-band clock stream is sent in SAToP (unframed) format.

Router Recovering Clock (Slave Clock)

• The out-of-band clock signal is always recovered in adaptive mode. The clock signal can then be used to drive all of the ports on the CEoP SPA.
• Two CEM circuits (a primary and a secondary out-of-band channel) can be configured under a slave clock interface, one for each of two master clock signals. This way, the SPA can receive a master clock signal from two separate sources (that is, two master clocks).
• Under the slave clock interface, the xconnect command (used to create the out-of-band clock channel) must specify the router from which the master clock is recovered.

Configuration Overview

The following steps provide a high-level overview of the procedure for configuring out-of-band clocking between two CEoP SPAs. Detailed steps are provided in the sections that follow.

Before you begin, determine which CEoP SPAs have TDM devices connected to them. You must configure an out-of-band clock channel to deliver the clock signal from each SPA that sends TDM data to every destination SPA that receives the data.

1. Use the recovered clock command to identify the CEoP SPA that is to send TDM data across the MPLS network. This SPA’s clock is used as the master clock for out-of-band clocking.

2. Configure master and slave clock interfaces to represent the source (clock master) and destination (clock slave) for the out-of-band clock signal. The master and slave clock interfaces (and pseudowires) should be configured on different SPAs.

a. The master clock interface represents the master clock, which is distributed to all destination CEoP SPAs that receive data from the source TDM device connected to this SPA. (See the “Creating and Configuring the Master Clock Interface” section for instructions.)

b. Configure a slave clock interface on each of the SPAs connected to TDM devices that can receive data from the source TDM device. (See the “Configuring the Slave Clock Interface” section for detailed instructions.)

Note When you configure a master or slave clock interface, the router creates a virtual CEM interface to represent this out-of-band clock. The virtual CEM interface has the same slot and subslot information as the CEoP SPA from which the master clock is recovered. The port number is always 24. For example, if the clock signal is recovered from the SPA in slot 8, subslot 1 (recovered-clock 8 1), the virtual CEM interface is virtual-cem8/1/24.

3. Under both the master and slave clock interfaces, use the cem circuit-id command to configure CEM circuits to represent the out-of-band channels that will distribute the clock signal over the MPLS network. Each CEM circuit represents a separate out-of-band channel for delivering the clock signal from the source (master clock) to a destination TDM device (slave clock). The out-of-band clock channel is created when you issue the xconnect command in the next step.

– Under the master clock interface, you can configure up to 64 CEM circuits, one for each of the destination TDM devices that will use this clock signal as its master clock.

– Under the slave clock interface (on the destination TDM device), you can configure one or two CEM circuits. Two CEM circuits are allowed because the clock slave can receive a clock signal from two master clocks.

Note Each out-of-band clock channel requires two CEM circuits (one on the master clock interface and one on the slave clock interface). Each CEM circuit represents the CEM attachment circuit at one end of the out-of-band clock channel.

4. Create the out-of-band channel for the clock signal by using the xconnect command to configure two pseudowires between the CEM circuit on the master clock interface and the CEM circuit on the slave clock interface. The master clock pseudowire and slave clock pseudowire should be on different SPAs; however, you should use the same VCID for both pseudowires.

a. Under the master clock interface, configure a pseudowire to the destination device (slave clock).

b. Under the slave clock interface (on the SPA that connects to the destination TDM device), configure a pseudowire to the router that contains the master clock interface.

Creating and Configuring the Master Clock Interface

To create the master clock interface for out-of-band clocking, perform the following steps:

To configure the out-of-band channel to use for the master clock signal, perform the following steps:

Note A CEoP SPA cannot be configured as both master and slave at the same time. To reconfigure a SPA’s clock type, you must first remove the existing clock configuration.

Configuring the Slave Clock Interface

To configure the slave clock interface and out-of-band channel to use for out-of-band clocking, perform the following steps. Configure a slave clock interface on every CEoP SPA that receives TDM data from the SPA configured as the master clock in the preceding section.

Verifying Out-of-Band Clocking

This section lists the show commands that you can use to verify the out-of-band clocking configuration.

• Use the show ip interface brief command to display the virtual CEM interfaces that the router created to represent master and slave clock interfaces. The output in the following example shows only the virtual CEM interface. Information for all other interfaces is omitted from the display.

• Use the show cem circuit command to display a list of CEM circuits configured on the SPA. The command displays both normal and out-of-band clocking CEM circuits.

• Use the show cem interface virtual-cem slot / subslot / port command to display information about a particular virtual CEM interface:

• Use the show run interface virtual-cem slot / subslot / port command to dislay the current running configuration for the specified interface:

• Use the show run | begin recovered command to display the recovered clock being used for out-of-band clocking:

• On the clock slave, you can use the show recovered-clock command to display the status of the out-of-band clock:

Removing the Out-of-Band Clocking Configuration

Use the following commands to delete the various components used for out-of-band clocking:

• To remove a CEM circuit, use the no cem circuit-id command (where circuit-id is the number assigned to the circuit). Issue the command under the virtual CEM interface where the circuit exists.

• To remove a virtual CEM interface, use the no clock master or no clock slave command in recovered-clock configuration mode, as shown in the following examples. Note that the virtual CEM interface is not deleted when you remove the last CEM circuit under the interface.

In the following example, the no clock slave command deletes the slave clock interface for the recovered clock (which is 8/1):

Out-of-Band Clocking Configuration Example

This section provides an example of how to configure out-of-band clocking between two CEoP SPAs. It is divided into several different configuration sections.

Configuring the Master Clock Interface

The following example shows how to configure a CEoP SPA as a master clock and verify the configuration:

Configuring the Slave Clock Interface

Verifying the Virtual CEM Interface Configuration

The router creates a virtual CEM interface when you configure either the master or slave clock interface. You can view the interface using the show ip interface brief command:

Configuring CEM Circuits for Out-of-Band Clocking Example

This section provides an example of how to configure CEM circuits and pseudowires for out-of-band clocking. The sample configuration shows the circuits and pseudowires configured on a CEoP SPA in PE1, which sends TDM data to another CEoP SPA in PE2.

You configure CEM circuits for the master and slave clocks under the virtual CEM interface that represents the recovered clock that is being used for out-of-band clocking. This differs from normal CEM circuits, which are configured under the SPA controller through the cem-group command.

Issuing the xconnect command under the master and slave CEM circuits configures an out-of-band clock channel to use to send the clock signal from the sending SPA to the receiving SPA. Note that normal CEM pseudowires are configured under the SPA controller interface.

Out-of-Band Clocking (PE1)

Out-of-Band Clocking (PE2)

Configuring Payload Size (Optional)

To specify the number of bytes encapsulated into a single IP packet, use the pay-load size command. The size argument specifies the number of bytes in the payload of each packet. The range is from 32 to 1313 bytes.

Default payload sizes for an unstructured CEM channel are as follows:

• E1 = 56 bytes
• T1 = 192 bytes
• T3/E3 = 1024 bytes

Default payload sizes for a structured CEM channel depend on the number of time slots that constitute the channel. Payload size (L in bytes), number of time slots (N), and packetization delay (D in milliseconds) have the following relationship: L = 8*N*D. The default payload size is selected in such a way that the packetization delay is always 1 millisecond. For example, a structured CEM channel of 16xDS0 has a default payload size of 128 bytes.

The payload size must be an integer of the multiple of the number of time slots for structured CEM channels.

Effective with Cisco IOS release 12.2 SRB for Cisco 7600 and later releases, configuring the payload size for virtual cem interfaces is possible only at interface level and not allowed on the cem circuit mode. On normal cem interfaces, the payload size can be configured on the cem circuit mode.

If you try to configure payload size in cem circuit mode for a virtual cem interface, the router shows a warning message as given in the following example:

Instead of that, you can configure payload size at the interface level for the virtual cem interface as shown in the following example.

Setting the Dejitter Buffer Size

To specify the size of the dejitter buffer used to compensate for the network filter, use the dejitter-buffer size command. The configured dejitter buffer size is converted from milliseconds to packets and rounded up to the next integral number of packets. Use the size argument to specify the size of the buffer, in milliseconds. The range is from 1 to 500 ms; the default is 5 ms.

Setting the Idle Pattern (Optional)

To specify the idle pattern, use the [ no ] idle-pattern pattern1 command. The payload of each lost CESoPSN data packet must be replaced with the equivalent amount of the replacement data. The range for pattern is from 0x0 to 0xFF; the default idle pattern is 0xFF.

Enabling Dummy Mode

Dummy mode enables a bit pattern for filling in for lost or corrupted frames. To enable dummy mode, use the dummy-mode [ last-frame | user-defined ] command. The default is last-frame. The following is an example:

Setting the Dummy Pattern

If dummy mode is set to user defined, you must use the dummy-pattern pattern command to configure the dummy pattern. The range for pattern is from 0x0 to 0xFF. The default dummy pattern is 0xFF. The following is an example:

Shutting Down a CEM Channel

To shut down a CEM channel, use the shutdown command in CEM configuration mode. The shutdown command is supported only under CEM mode and not under the CEM class.

Restrictions and Usage Guidelines

Follow these restrictions and usage guidelines while configuring ACR on CEoP and ATM SPAs:

• ACR support for CEoP SPAs is applicable for ATM, IMA, and CEM interfaces on the same router. The support is not extended for multi level routers.
• Configure the frame manually under the virtual controller and two physical member controllers. This is consistent across the interfaces.
• You can configure a maximum of 256 controllers on the ACR groups on a single router. But the Cisco 7600 router can hold a maximum of 44 CEoP SPAs, which restricts the maximum number of ACR controllers to 22.
• You cannot configure ACRs within the physical ATM, CEM, or IMA interfaces that are part of the ACR group, but allowed on the ATM-ACR, CEM-ACR, IMA-ACR interfaces.

Configuring the ACR Group

This section provides the configuration for ACR in ATM, IMA, and CEM interfaces.

SUMMARY STEPS

Step 1 enable

Step 2 configure terminal

Step 3 controller sonet slot/subslot/port

Step 4 aps group acr acr no

Step 5 aps working circuit number

Step 6 exit

Step 7 controller sonet slot/subslot/port

Step 8 aps group acr acr no

Step 9 aps protect circuit number ip-address

Step 10 aps revert minutes

Step 11 exit

DETAILED STEPS

Example 11-1 Configuring ACR Interface

This is an example for configuring ACR interface:

Verifying ACR Group

Configuring CEM, ATM, and IMA Interfaces

This section provides the configuration for CEM, ATM, and IMA interfaces:

SUMMARY STEPS

Step 1 enable

Step 2 configure terminal

Step 3 controller sonet 5/1/0

Step 4 sts-1 2

Step 5 vtg 3 t1 2 atm

or

vtg 1 t1 1 ima-group group-number

or

vtg 2 t1 1 cem-group 1 unframed