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Cisco IOS Release 12.0(23)SX

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Release Notes for the Cisco 10000 Series ESR for Cisco IOS Release 12.0(23)SX

Table Of Contents

Release Notes for the Cisco 10000 Series ESR
for Cisco IOS Release 12.0(23)SX


Upgrading to a New Software Release

Upgrading from Earlier Cisco IOS Releases

Upgrading Software on Redundant PREs

System Requirements

Memory Requirements

New Features in Cisco IOS Release 12.0(23)SX

Multirouter-Automatic Protection Switching

Multicast for MPLS/VPN

MPLS Traffic Engineering Fast Reroute

DiffServe Aware Traffic Engineering for MPLS

eiBGP Multipath Load Sharing

Link Fragmentation and Interleaving

Single Rate 3-Color Marker for Traffic Policing

Cisco 10000 ESR MIB Enhancements

SNMP Trap Filtering

Limitations and Restrictions

Important Notes

Open Caveats in Cisco IOS Release 12.0(23)SX

Obtaining Documentation

World Wide Web

Documentation CD-ROM

Ordering Documentation

Documentation Feedback

Obtaining Technical Assistance

Technical Assistance Center

Cisco TAC Web Site

Cisco TAC Escalation Center

Release Notes for the Cisco 10000 Series ESR
for Cisco IOS Release 12.0(23)SX

January 17, 2003

These release notes provide information about Cisco IOS Release 12.0(23)SX for the Cisco 10000 series edge services router (ESR). These release notes are updated as needed to describe new features, memory requirements, hardware support, software platform deferrals, and changes to the microcode and related documents.

Cisco IOS Release 12.0(23)SX is based on Cisco IOS Release 12.0(23)S and includes all of the new features introduced in that release. To review the release notes for Cisco IOS Release 12.0(23)S, go to and click Technical Documents > Aggregation > Cisco 10000 Series Edge Services Routers > Cisco 10000 Series ESR Release Notes > Release Notes for the Cisco 10000 Series ESR for Cisco IOS Release 12.0(23)S.

To see the release notes for Cisco IOS Release 12.0(23)S, go to the following URL:


These release notes contain the following sections:

Upgrading to a New Software Release

System Requirements

New Features in Cisco IOS Release 12.0(23)SX

Limitations and Restrictions

Important Notes

Open Caveats in Cisco IOS Release 12.0(23)SX

Obtaining Documentation

Obtaining Technical Assistance

Upgrading to a New Software Release

For specific information about upgrading your Cisco 10000 series ESR to a new software release, see the Cisco 10000 Series ESR Software Configuration Guide at the following URL:

For general information about how to upgrade to a new software release, see the product bulletin Cisco IOS Upgrade Ordering Instructions located at:

For information about how to order Cisco IOS software, refer to the Cisco IOS Software Releases URL:

Upgrading from Earlier Cisco IOS Releases

Upgrading from Cisco IOS Release 12.0(21)SX or Release 12.0(21)SX1

If you are upgrading your software from Cisco IOS Release 12.0(21)SX or Release 12.0(21)SX1 to Cisco IOS Release 12.0(22)S, you must upgrade the eboot image on the Cisco 10000 series edge services router (ESR). If you fail to upgrade the eboot image, the ESR configuration may not load properly, and a checksum error appears on the console. If you are upgrading the software from an earlier Cisco IOS release, you do not need to upgrade the eboot image.

Upgrading from Cisco IOS Release 12.(14)SL or from Earlier 12.0(x)SL-based Releases

If you are upgrading your software from Cisco IOS Release 12.0(14)SL or from earlier 12.0(x)SL-based releases to Cisco IOS Release 12.0(22)S, save your current configuration file. If you decide to reinstall Release 12.0(14)SL or an earlier release, you must also reinstall the configuration file associated with that release. This is because some Border Gateway Protocol (BGP) configuration-file entries in Release 12.0(22)S are not compatible with Release 12.0(14)SL or earlier releases.

Upgrading Software on Redundant PREs

When you upgrade software on redundant Cisco 10000 series Performance Routing Engines (PREs), be sure to download the software to both the active PRE and the standby PRE before you reload both PREs. For more information, refer to the "Upgrading Software on Redundant PREs" section in the "System Startup and Basic Configuration Tasks" of the Cisco 10000 Series ESR Software Configuration Guide at the following URL:

Note In the procedure at the above URL, specify c10k-p10-mz instead of c10k-p6-mz for image name.

System Requirements

This release requires that you have the PRE1 version (part number ESR-PRE1) of the Performance Routing Engine (PRE) installed in the Cisco 10000 series ESR chassis. To verify which PRE is installed in the ESR, use the show version command.

Memory Requirements

The following table lists memory requirements for the ESR.

Feature Set by Router
Image Name
Flash Memory
DRAM Memory
Runs From

Edge Services Router


40 MB

512 MB


Service Provider/ Secured Shell 3DES


40 MB

512 MB


New Features in Cisco IOS Release 12.0(23)SX

The following sections describe the new features and improvements being introduced in Cisco IOS Release 12.0(23)SX:

Multirouter-Automatic Protection Switching

Multicast for MPLS/VPN

MPLS Traffic Engineering Fast Reroute

DiffServe Aware Traffic Engineering for MPLS

eiBGP Multipath Load Sharing

Link Fragmentation and Interleaving

Single Rate 3-Color Marker for Traffic Policing

Cisco 10000 ESR MIB Enhancements

SNMP Trap Filtering

Multirouter-Automatic Protection Switching

The multirouter-automatic protection switching (MR-APS) feature allows switchover of SONET connections in the event of circuit failure. MR-APS is often required when connecting SONET equipment to telco equipment. APS refers to the mechanism of using a "protect" SONET interface in the SONET network as the backup for a working SONET interface. When the working interface fails, the protect interface quickly assumes its traffic load.

The protection mechanism provided by MR-APS has a linear 1+1 architecture, as described in the Bellcore publication TR-TSY-000253, SONET Transport Systems; Common Generic Criteria, Section 5.3. The connection may be bidirectional or unidirectional, and revertive or non-revertive.

MR-APS provides a protection mechanism in which the "working" and "protect" SONET interfaces are on separate routers. MR-APS also allows both interfaces to be on the same router. However, in this case, we recommend you use single router-APS instead.

Single router-APS (SR-APS) provides a protection mechanism in which the working and protect interfaces are both on the same router. This protection mechanism provides a linear 1+1 unidirectional, non-revertive architecture. Note that the ESR supports bridging in the SR-APS implementation.

For more information on this feature, see the following URL. Note that the documentation includes aps commands for POS interfaces. However, the same commands also apply for ATM interfaces.

Recommendation for MR-APS Configurations with Limited Static Routes

If your MR-APS configuration has a limited number of static routes (for example, less than 10), we recommend that you use the following command for gigabit Ethernet, ATM, and POS interfaces that have static routes configured for them.

Router(config-if)# ip route static update immediate 

The command adds static routes to the routing table immediately when an interface becomes active, rather than after a route dampening period ends.


Currently, the ESR supports MR-APS only on OC-12ATM interfaces.

The aps reflector command is not supported in this release.

Multicast for MPLS/VPN

The Multicast for Multiprotocol Label-Switching (MPLS)/Virtual Private Network (VPN) feature allows service providers to offer multicast services over their MPLS core network. Multicast for MPLS/VPN allows end-user customers to improve productivity and communication flow for applications such as corporate communication, e-learning, data warehousing, content synchronization, trading stocks and commodities (stock quotes and ticker information), and emergency messaging services.

Live video and Video-on-Demand applications also require a multicast solution that offers scalability, efficiency, and performance. As demand grows for multicast and VPN, enterprises will require service providers to enable multicast across VPNs. Multicast for MPLS/VPN provides that solution.

MPLS Traffic Engineering Fast Reroute

The Fast Reroute (FRR) link protection feature of MPLS traffic engineering provides link protection to label-switched paths (LSPs). MPLS traffic engineering automatically establishes and maintains LSPs across the backbone using Resource ReSerVation Protocol (RSVP). Paths for LSPs are calculated at the headend, based on the LSP resource requirements and available network resources such as bandwidth. Under failure conditions, the headend determines a new route for the LSP. This provides for the optimal use of resources. However, due to messaging delays, recovery at the headend is not as quick as recovery at the point of failure.

FRR link protection enables the router to reroute traffic around a failed link without involving the headend in the rerouting decision. This provides quicker recovery time and prevents any further packet loss caused by the failed link. The headend of the tunnel is also notified of the link failure through the IGP or RSVP; the headend then attempts to establish a new LSP that bypasses the failure. For more information about this feature, see the following URL:

Note Local reroute prevents any further packet loss caused by a failed link, and gives the headend of the tunnel time to re-establish the tunnel along a new, optimal route.


The Fast Reroute link protection feature works only on:

Packet over SONET (POS) links (SDH in the European standard)

Links that use MPLS global label allocation (GLA)

DiffServe Aware Traffic Engineering for MPLS

The DiffServer Aware Traffic Engineering feature extends DiffServe quality of service (QoS) over an MPLS backbone that uses traffic engineering. Bandwidth pools assigned to tunnel interfaces ensure that critical data is associated with a tunnel that has enough bandwidth to transport data over the MPLS network. For information about this feature, see the following URL:

eiBGP Multipath Load Sharing

This section describes the Border Gateway Protocol (BGP) Multipath Load Sharing for external BGP (eBGP) and internal BGP (iBGP) in a Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN) feature. This feature allows you to configure multihomed autonomous systems and provider edge (PE) routers to:

Distribute traffic across eBGP and iBGP paths in BGP networks

Import eBGP and iBGP paths from multihomed and stub networks

BGP installs up to the maximum number of paths allowed (configured by the maximum-paths command). BGP uses the best path algorithm to select one multipath as the best path, insert the best path into the routing information base (RIB), and advertise the best path to BGP peers. Other multipaths may be inserted into the RIB, but only one path will be selected as the best path.

The multipaths are used by Cisco Express Forwarding (CEF) to perform load balancing on a per-packet or per-source or destination pair basis. The eiBGP Multipath Load Sharing feature performs unequal cost load balancing by default by selecting BGP paths that do not have an equal cost of the Interior Gateway Protocol (IGP). To enable this feature, configure the router with MPLS VPNs that contain VPN routing and forwarding instances (VRFs) that import both eBGP and iBGP paths. The number of multipaths can be configured separately for each VRF.

Note This feature operates within the configuration parameters of the existing outbound routing policy.

For more information about this feature, see the following URL:


Route Reflector Limitation—With multiple iBGP paths installed in a routing table, a route reflector will advertise only one of the paths (one next hop). If a router is behind a route reflector, all routers that are connected to multihomed sites will not be advertised unless separate VRFs with different RDs are configured for each VRF.

Memory Consumption Restriction—Each IP routing table entry for a BGP prefix that has multiple iBGP paths uses additional memory. We recommend not using this feature on a router with a low amount of available memory and especially when the router is carrying a full Internet routing table.

Link Fragmentation and Interleaving

Interactive traffic (Telnet, voice on IP, and the like) is susceptible to increased latency and jitter when the network processes large packets, (LAN-to-LAN FTP transfers traversing a WAN link, for example), especially as they are queued on slower links.

The Link Fragmentation and Interleaving (LFI) feature reduces delay and jitter on slower-speed links by breaking up large datagrams and interleaving low-delay traffic packets (such as voice) with the smaller packets resulting from the fragmented datagram. LFI was designed especially for lower-speed links where serialization delay is significant.


The Cisco 10000 series ESR implementation of LFI provides the following benefits:

Supports the following encapsulation protocols:

Frame Relay (FRF.12) end-to-end

Multilink PPP (MLPPP)

Supports LFI on up to 1000 ESR interfaces.

Prioritized traffic is always sent intact, while all other traffic is subject to fragmentation.

During packet reassembly, the ESR detects and discards any packets that are missing fragments.

Cisco 10000 Series ESR LFI Limitations and Restrictions

The following limitations and restrictions apply to the Cisco 10000 series ESR implementation of LFI:

Multilink LFI is restricted to 1-link bundles only.

Multilink PPP must be enabled on an interface that has interleaving turned on.

To enable LFI on an MLPPP interface, use the ppp multilink interleave command.

Multilink PPP over ATM (MLPoATM) is not supported.

The show frame-relay fragment command does not support the following statistics:

fragments received (in_frag)
fragments dropped (drop_frag)
fragments transmitted (out_frag)

The show frame-relay fragment interface command does not support the following statistics:

in fragmented pkts
in fragmented bytes
in dropped reassembling packets
in timeouts
out interleaved packets
out fragmented pkts
out fragmented bytes
out dropped fragmenting pkts

Cisco 10000 Series ESR LFI Implementation Notes

The following sections provide information about the LFI implementation on the Cisco 10000 series ESR:

MLPPP LFI Packet Counts

Configuring LFI on a Frame Relay Interface—Method 1

Configuring LFI on a Frame Relay Interface—Method 2

Configuring LFI on a Multilink PPP Interface

MLPPP LFI Packet Counts

On an MLPPP interface that has LFI enabled, each packet fragment is counted as a separate packet in the interface's input and output statistics. For example, if a single packet is fragmented into three packets, the the show interface stats command and the show interfaces commands show a count of 3 for Packets In and Packets Out, rather than a count of 1.

Configuring LFI on a Frame Relay Interface—Method 1

One way to configure LFI on a Frame Relay data-link connection identifier (DLCI) is to:

Use the command frame-relay interface-queue fair to enable Frame Relay weighted fair queuing on the physical interface.

Create a Frame Relay map-class that defines the traffic to prioritize for interleaving. You can also include the following command to define a priority queue for an RTP packet flow:

frame-relay ip rtp priority start_port_number port_range [max_bandwidth]

Set the LFI fragmentation size (in bytes) by including the following command in the map-class. Specify a fragmentation size of at least 128 bytes, which is the minimum size supported by the ESR.

frame-relay fragment fragment_size

Attach the map-class to the DLCI.

Use the Frame Relay QoS CLI to configure user-defined queues on the DLCI.

The following is a sample configuration showing this method of configuring LFI. (In this example, fragment size is 384 bytes and the bandwidth for the priority queue is 307 kbps.)

interface Serial5/0/0.1/1:0
encapsulation frame-relay
 frame-relay class PQ_FR_CLASS_0
 frame-relay interface-dlci 17
 frame-relay interface-queue fair

map-class frame-relay PQ_FR_CLASS_0
  frame-relay fragment 384
  frame-relay ip rtp priority 16384 10 307

Configuring LFI on a Frame Relay Interface—Method 2

You can also use a nested policy and access lists to configure LFI on a Frame Relay DLCI as follows:

Use the priority command to create a priority queue and use a policy map to associate a class of traffic with the priority queue.

policy-map qos_pq_cbwfq_0
  class acl_101
    priority percent 10

Create a nested policy and include it in the Frame Relay map class.

Use the following command to set the fragmentation size (in bytes). Specify a fragmentation size of at least 128 bytes, which is the minimum fragmentation size supported by the ESR.

frame-relay fragment fragment_size

The following is a sample configuration showing this method of configuring LFI. (In the example, fragmentation size is 768 bytes and bandwidth for the priority queue is 10 percent of the link bandwidth.)

interface Serial5/0/0.1/1/1/1:0
 ip address
 no ip directed-broadcast
 encapsulation frame-relay
 frame-relay class PQ_FR_CLASS_0
 frame-relay interface-dlci 17

access-list 101 permit udp any eq 16384 any eq 16384
access-list 102 permit udp any eq 3000 any eq 3000

class-map match-all acl_101
  match access-group 101
class-map match-all acl_102
  match access-group 102

policy-map qos_pq_cbwfq_0
  class acl_101
    priority percent 10
  class acl_102
    bandwidth percent 30
policy-map outer_policy
  class class-default
    shape 768
    service-policy qos_pq_cbwfq_0

map-class frame-relay PQ_FR_CLASS_0
 service-policy output outer_policy
 frame-relay fragment 768

Configuring LFI on a Multilink PPP Interface

To configure LFI on an MLPPP interface, do the following:

Use the following commands to configure multilink operation on the interface:


ppp multilink

Enables multilink operation on the interface.

ppp multilink fragmentation

Enables multilink fragmentation on the interface.

ppp multilink fragment-delay milliseconds

(Optional) Specifies the maximum delay (in milliseconds) for fragmentation (for example, you can specify that voice traffic has a maximum fragmentation delay of 20 milliseconds). MLP uses this value to choose a fragment size.

ppp multilink interleave

Enables real-time packet interleaving on the bundle.

Identify the traffic to prioritize for interleaving.

Use the priority command to create a priority queue and use a policy map to associate that class of traffic with the priority queue. The priority command gives priority to a class within the policy map.

Attach the policy map to an interface to assign that traffic classification and action to the interface.

The following commands show an example of how to configure LFI on an MLPPP interface:

	class-map match-all VOIP
	  match ip rtp 16384 16383
	class-map LESS_CRITICAL
	  match access-group 101
	policy-map VOIP_PRI
	  class VOIP
	    priority 50
	    set ip precedence 5
	interface Multilink1
	  ppp chap hostname multilink_name-1
	  ppp multilink
	  ppp multilink fragment-delay 8
	  ppp multilink interleave
	  service-policy output VOIP_PRI
	  multilink-group 1

	  interface Serial 2/1
	  encapsulation ppp
	  ppp multilink
	  multilink-group 1

Note The ip rtp priority command is not included as a policy action. Instead, the priority configuration defined on the interface determines which traffic is placed in the priority queue.

Single Rate 3-Color Marker for Traffic Policing

The single rate 3-Color Marker feature meters an IP packet stream and marks its packets different colors, based on the Committed Information Rate (CIR) and two associated burst sizes: Committed Burst Size (CBS) and Excess Burst Size (EBS). CIR is measured in bytes of IP packets per second (and it includes the IP header, but not link specific headers). CBS and EBS are measured in bytes.

Previously, the ESR supported a single rate, 2-color marker. The single rate, 3-color marker allows the ESR to classify packets that violate the EBS. This feature is useful, for example, for ingress policing of a service, where service eligibility is determined only by the burst's length, and not its peak rate.

The single rate 3-color marker uses the following colors to classify packets:

Green (conforming)—Packet size is at most Bc or CBS and within the CIR allowance.

Yellow (exceeding)—Packet size is greater than the CIR allowance but is at most Be or EBS bytes and within the available surplus.

Red (violating)—Packet size is greater than both the CIR allowance and the available surplus. This is because either the packet's size exceeds Be or EBS or because a previous packet used some of the surplus and the traffic since then has not slowed sufficiently to acquire the surplus needed for the current packet.

The marker starts with a surplus equal to Be or EBS, and replenishes the surplus by the amount of unused CIR allowance until the surplus reaches Be or EBS.

Configuring the Single Rate Three-Color Marker Feature

To configure this feature, do the following:

Use the police command to set the feature's mode and to assign values for the CIR, CBS, and EBS:

Router(config-pmap-c)# police CIR CIR_bps burst-normal burst-max conform-action action 
exceed-action action violate-action action

For conform, exceed, and violate action, you can specify one of the following actions: transmit, set-dscp-transmit, set-prec-transmit, set-mpls-exp-transmit, or set-qos-transmit.

Using the Feature

The 3-color marker can be used to mark a packet stream in a service, where different, decreasing levels of assurances (either absolute or relative) are given to packets which are green, yellow, or red. For example, a service might:

Discard or deny all red packets because they exceed both the committed and excess burst sizes.

Forward green packets because they are guaranteed for delivery.

Cisco 10000 ESR MIB Enhancements

MIB capabilities on the Cisco 10000 series ESR have been enhanced as follows:



Support was added for MPLS-LSR-MIB mplsInSegmentOctets and mplsInSegmentOctets.

The IF-MIB was enhanced to support MPLS.

MIBs were enhanced to support the ESR high-availability feature.

For more information about the ESR MIB capabilities for this release, see the Cisco 10000 Series ESR Leased Line MIB Specifications Guide (version 3) at the following URL. (Table 3-1 in the "MIB Specifications" section of the guide lists the MIBs supported in this release.)

SNMP Trap Filtering

Use the SNMP trap filtering feature to filter linkdown traps so that SNMP only sends a linkdown trap if the main interface goes down. If a Cisco 10000 series ESR interfaces goes down, all of its subinterfaces go down, which results in numerous linkdown traps for each subinterface. This feature filters out those subinterface traps. This feature is turned off by default.

To enable the SNMP trap filtering feature, issue the following CLI command. Use the no form of the command to disable the feature.

[no] snmp ifmib trap throttle 

Limitations and Restrictions

PRE Network Management Ethernet Port

Ensure that the Fast Ethernet NME port on the PRE is configured for auto-negotiation mode, which is the system default. Duplex mode can cause problems, such as flapping. If the port is experiencing such problems and has been configured for duplex mode, use the no half-duplex or no full-duplex command to disable duplex mode.

Controlling the Rate of Logging Messages

It is important that you limit the rate that system messages are logged by the Cisco 10000 series ESR. This helps to avoid a situation in which the router becomes unstable and the CPU is overloaded. To control the output of messages from the system, use the logging rate-limit command.

We recommend that you configure the logging rate-limit command as follows:

Router(config)# logging rate-limit console all 10 except critical 

This rate-limits all messages to the console to 10 per second, except for messages with critical priority (level 3) or greater.

For more information on the logging rate-limit command, see the Cisco IOS Configuration Fundamentals Command Reference.

Frame Relay

The following limitations apply to the Cisco 10000 series ESR implementation of Frame Relay:

The ip rtp reserve command is not supported.

Only one priority queue per VC is allowed.

Nested Policy Feature

The following limitations and restrictions apply to the Cisco 10000 series ESR nested policy feature:

Nested policies support no more than two hierarchy levels.

For additional restrictions and limitations on creating nested policies, refer to the "Configuring Nested Policies on the ESR" section of the Cisco document at the following location:

The nested-policy shape rate is reserved for nested-policy traffic only. Excess bandwidth is not used for other traffic.

DotP marking is not supported, nor is 802.1P (including matching and marking the 802.1P header).

Note The actual shape rate applied to nested-policy traffic might differ from that specified in the policy. For example, a specified shape rate of 10.5 Mbps might be mapped to 11 Mbps. Use the command show policy-map interface to determine the actual shape rate.

Testing Performance of High-Speed Interfaces

Cisco IOS software running on the Cisco 10000 series ESR has multiple queues for all classes of traffic over high-speed interfaces. The software selects a queue based on the source and destination address for the packet. This ensures that a traffic flow always uses the same queue and the packets are transmitted in proper order.

When the Cisco 10000 series ESR is installed in a real network, the high-speed interfaces work efficiently to spread traffic flow equally over the queues. However, using single traffic streams in a laboratory environment may result in less-than-expected performance.

Therefore, to ensure accurate test results, you should test the throughput of the gigabit Ethernet, POS, or ATM uplink with multiple source or destination addresses.

Tip To determine if traffic is being properly distributed, use the show hardware pxf cpu queue command.

Important Notes

Cisco Discovery Protocol

Unlike other Cisco routers, on the Cisco 10000 series ESR the Cisco Discovery Protocol (CDP) is disabled by default. You can enable CDP on an interface using the cdp enable command.

Frame Relay and PPP Sessions

You can run up to 4000 Frame Relay sessions or 4000 PPP sessions, and you can configure up to 800 Border Gateway Protocol (BGP) peers on the Cisco 10000 series ESR. The ESR also supports up to 512 Multilink Point-to-Point (MLP) protocol sessions and up to 1024 MLP bundles.

Performance Routing Engine 1 (PRE1) on the Cisco 10000 Series Edge Services Router

In order for Cisco IOS Release 12.0(22)S and later releases to run on the Cisco 10000 series edge services router, the Performance Routing Engine (PRE) installed in the chassis must be the PRE1 version (part number ESR-PRE1). You can verify which PRE is installed in the chassis by using the show version command.

Note The Cisco 10000 series ESR does not support mixing two different PRE revisions in the same chassis. Do not install a PRE and PRE1 in the same chassis.

VLAN Session Support

The Cisco 10000 series ESR provides session support for 4000 802.1Q VLANs.

Inserting a New Line Card

Unlike other Cisco routers, if you insert a new or different line card into a Cisco 10000 series ESR chassis slot that previously had a line card installed, the line card initially reports that it is administratively up.

RBE Subinterfaces

To ensure that the Performance Routing Engine (PRE) microcode has adequate IP address space, use IP addresses in a contiguous address space. Also, use the ip unnumbered command on the RBE subinterface.

Open Caveats in Cisco IOS Release 12.0(23)SX

Table 1 describes the open caveats in Cisco IOS Release 12.0(23)SX.

Table 1 Open Caveats in Cisco IOS Release 12.0(23)SX 


SNMP returns incorrect values for the MIB objects atmTrafficDescrType and atmTrafficQoSClass for all types of PVCs.

Workaround: Use the command show atm pvc to determine the QoS class and use the class to determine the proper atmTrafficDescrType value.


After a stateful switchover (SSO) in a redundant PRE system, the MIB objects ifLastChange (IF-MIB) and atmVclLastChange (ATM-MIB) might not match sysUpTime.0 (MIB-2), but they should. This problem can occur:

After a second switchover

When the standby PRE is reset, followed by a switchover

When the standby PRE is inserted in the chassis later, after the primary PRE

Workaround: None.


The Parallel eXpress Forwarder (PXF) diversion statistics do not clear when you issue the microcode reload all command, although they should.

Workaround: Reload the Cisco IOS software.


The MIB object ifOperStatus incorrectly shows T1 layers on channelized OC-12 and channelized STM line cards as Up when all other layers are Down.

Workaround: Check the status of the lower layers. When ifOperStatus is Down, the T1 layer should also be Down. Or use the show controller {t3 | sonet } command to see the operational status of lower layers.


After you issue the commands shutdown and no shutdown on a channelized OC-12 line card, the show controller t3 command incorrectly displays the T3 controller as Down. The controller is really Up.

Workaround: Issue the shutdown command, wait several seconds, and then issue the no shutdown command on the SONET interface. Doing so sets the T3 interface to Up in the show controller t3 command.


A traceback occurred during SSO testing of PPP.

Workaround: None.


A routing policy does not count packets of 65 bytes or larger. The packets are transported, but not counted.

Workaround: None.


A traceback occurred during testing of IP multicast.

Workaround: None.


While using the 3-color policer to police 1000 VLANs, a traceback message appeared.

Workaround: None.


The 4-port channelized OC-3 line card experiences low through put and packet loss when configured with 252 SONET interfaces (VT E1 unframed).

Workaround: None.


On a channelized 4-port STM-1 line card with 756 interfaces, each at 512 Kbps with SDH framing and AU-4-TUG-3 controllers, the line protocol failed to initialize for several interfaces.

Workaround: None.


A PXF failure can occur when a fast reroute (FRR) is performed after a primary link fails. This problem was observed when the ESR was configured as an MPLS traffic engineering (TE) tunnel head and fast reroute (FRR) break point, and the primary link had 500 tunnels.

Workaround: None.

SNMP and MIBs ( see also General)

After 24 hours, information for all but the most recent interval is deleted from the sonetVTIntervalTable and sonetFarEndVTIntervalTable (SONET-MIB). Intervals are started again at 1, which means the tables contain intervals 1 and 95 (the most recent interval). If you attempt to perform a MIB walk, a loop occurs.

Workaround: Use the show vt controller tabular command to view interval data.


The SONET-MIB does not update the intervals in the sonetVTIntervalTable or sonetVTFarEndIntervalTable for channelized STM and channelized OC-12 AU-3 TU controllers.

Workaround: None.

Stateful Switchover

After a stateful switchover (SSO), the first packet sent through UDP is lost.

Workaround: Issue the following CLI command to configure the ESR to check before sending the first IP packet to make sure that an ARP entry exists for the destination (which must be connected through a fast Ethernet interface). In the command, A.B.C.D is the destination IP address and H.H.H is the 48-bit hardware address.

conf t 
arp  A.B.C.D  H.H.H


After a stateful switchover, an ESR with redundant PRE-1 cards and channelized OC-12 or channelized STM line cards can experience a traceback and %CEF fibidb error message.

Workaround: None.

Multicast for MPLS/VPN

Under rare circumstances, an ESR configured for multicast VPN does not form a data multicast distributed tunnel (MDT) consistently.

Workaround: None.

eiBGP Multipath Load Sharing

If eiBGP multipath is configured in an MPLS network and one of the links is configured as eBGP, traffic may not be distributed through all links. This problem occurs when MAX Paths EIBGP is enabled under the address family. In this case, the IP BGP table displays multiple routes to a destination network (eBGP and iBGP paths), but the IP Route VPN table only shows iBGP paths.

Workaround: Disable eiBGP and use the weight command to forward traffic through eBGP or iBGP paths.


When the ESR is configured as a provider edge (PE) router with 100 VPNs, the number of packets reported at an ingress port might not reflect the actual number of packets forwarded by the ESR. This problem occurs on gigabit Ethernet (gigE) line cards when a gigE port is configured as a subinterface on a VLAN and traffic is sent to each VLAN ID from another router.

Workaround: None.


Traffic might not be load balanced through iBGP paths when MPLS eiBGP or iBGP max-paths is configured. For example, two iBGP paths might exist to the next hop but the PXF only forwards traffic through one of them. This means one of the links is not being used.

Workaround: If traffic is being forwarded through the slower links, you can shut down the slower link to allow the faster link to forward traffic.

Link Fragmentation and Interleaving (LFI )

The show frame-relay fragment command truncates the Frame Relay interface name for Channelized 4-port STM-1 line cards.

Workaround: None.


When class-based weighted fair queuing (CBWFQ) is used with LFI enabled and multiple queues are configured for a link, packets are dropped from underloaded queues rather than overloaded (congested) queues. This problem occurs when traffic with different packet sizes is sent to different queues, which causes fragmentation on some queues but not others.

Workaround: Be sure to use a priority queue when you enable LFI.


When LFI is enabled on an MLP bundle running over a T1 channel, the output shape rate is less than 90% of the configured shape rate.

Workaround: None.


When the priority queue (PQ) is underloaded and fragmentation queues (FQs) are overloaded, the PQ's Max latency and Avg latency are higher than they should be, especially on low-speed links.

Workaround: None.


The show interface command input and output byte counts are wrong for MLP interfaces with LFI enabled. In addition, the output packet and byte counters do not always clear after a clear counters command is issued, but they should.

Workaround: None.


When LFI is enabled, the show frame pvc command sometimes shows invalid counts for input and output packets and bytes.

Workaround: None.


One of 1000 MLPPP LFI-enabled interfaces failed to become active after the commands shutdown and no shutdown were issued.

Workaround: None.


The show frame-relay fragment command "out-frag" count does not increment, but it should. In addition, when the interface keyword is included in the command, the "out fragmented" counts do not increment as they should.

Workaround: None.


Channelized T3 (CT3) line cards lock up when 1000 Frame Relay or MLP interfaces (each with a 512 Kbps channel) are configured over two CT3 line cards. This problem occurs when each interface has LFI enabled and fragment size set to 512 bytes, and queues are assigned the following link bandwidth: priority queue = 10%, fragmentation queue = 30%, default queue = 60%. In this case, the interfaces on one of the CT3 line cards lock up when the default queue reaches almost 50% of the link bandwidth.

Workaround: Do not use the configuration above.

Obtaining Documentation

The following sections describe how to obtain documentation from Cisco Systems.

World Wide Web

You can access the most current Cisco documentation on the World Wide Web at the following sites:

Documentation CD-ROM

Cisco documentation and additional literature are available in a CD-ROM package, which ships with your product. The Documentation CD-ROM is updated monthly and may be more current than printed documentation. The CD-ROM package is available as a single unit or as an annual subscription.

Ordering Documentation

Cisco documentation is available in the following ways:

Registered Cisco Direct Customers can order Cisco Product documentation from the Networking Products MarketPlace:

Registered users can order the Documentation CD-ROM through the online Subscription Store:

Nonregistered users can order documentation through a local account representative by calling Cisco corporate headquarters (California, USA) at 408 526-7208 or, in North America, by calling 800 553-NETS (6387).

Documentation Feedback

If you are reading Cisco product documentation on the World Wide Web, you can submit technical comments electronically. Click Feedback in the toolbar and select Documentation. After you complete the form, click Submit to send it to Cisco.

You can e-mail your comments to

To submit your comments by mail, use the following address:

Attn. Document Resource Connection
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-9883

We appreciate your comments.

Obtaining Technical Assistance

Cisco provides as a starting point for all technical assistance. Customers and partners can obtain online documentation, troubleshooting tips, and sample configurations from online tools by using the Cisco Technical Assistance Center (TAC) Web Site. registered users have complete access to the technical support resources on the Cisco TAC Web Site. is the foundation of a suite of interactive, networked services that provides immediate, open access to Cisco information, networking solutions, services, programs, and resources at any time, from anywhere in the world. is a highly integrated Internet application and a powerful, easy-to-use tool that provides a broad range of features and services to help you with these tasks:

Streamline business processes and improve productivity

Resolve technical issues with online support

Download and test software packages

Order Cisco learning materials and merchandise

Register for online skill assessment, training, and certification programs

If you want to obtain customized information and service, you can self-register on To access, go to this URL:

Technical Assistance Center

The Cisco Technical Assistance Center (TAC) is available to all customers who need technical assistance with a Cisco product, technology, or solution. Two levels of support are available: the Cisco TAC Web Site and the Cisco TAC Escalation Center.

Cisco TAC inquiries are categorized according to the urgency of the issue:

Priority level 4 (P4)—You need information or assistance concerning Cisco product capabilities, product installation, or basic product configuration.

Priority level 3 (P3)—Your network performance is degraded. Network functionality is noticeably impaired, but most business operations continue.

Priority level 2 (P2)—Your production network is severely degraded, affecting significant aspects of business operations. No workaround is available.

Priority level 1 (P1)—Your production network is down, and a critical impact to business operations will occur if service is not restored quickly. No workaround is available.

The Cisco TAC resource that you choose is based on the priority of the problem and the conditions of service contracts, when applicable.

Cisco TAC Web Site

You can use the Cisco TAC Web Site to resolve P3 and P4 issues yourself, saving both cost and time. The site provides around-the-clock access to online tools, knowledge bases, and software. To access the Cisco TAC Web Site, go to this URL:

All customers, partners, and resellers who have a valid Cisco service contract have complete access to the technical support resources on the Cisco TAC Web Site. The Cisco TAC Web Site requires a login ID and password. If you have a valid service contract but do not have a login ID or password, go to this URL to register:

If you are a registered user, and you cannot resolve your technical issues by using the Cisco TAC Web Site, you can open a case online by using the TAC Case Open tool at this URL:

If you have Internet access, we recommend that you open P3 and P4 cases through the Cisco TAC Web Site.

Cisco TAC Escalation Center

The Cisco TAC Escalation Center addresses priority level 1 or priority level 2 issues. These classifications are assigned when severe network degradation significantly impacts business operations. When you contact the TAC Escalation Center with a P1 or P2 problem, a Cisco TAC engineer automatically opens a case.

To obtain a directory of toll-free Cisco TAC telephone numbers for your country, go to this URL:

Before calling, please check with your network operations center to determine the level of Cisco support services to which your company is entitled: for example, SMARTnet, SMARTnet Onsite, or Network Supported Accounts (NSA). When you call the center, please have available your service agreement number and your product serial number.