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Cisco WAN Switching Modules

Field Notice: MPLS Defects


Updated March 15, 2002

March 1, 2002


Products Affected

Product

Comments

Cisco Platforms that Support MPLS

Only when configured for MPLS. See below for details.

MGX-RPM-*

MGX 8800 Route Processor Module

Cisco 7200 Series Routers

The two LSC issues affect RPM and 7200 (CSCdw59938 and CSCdw47263). If the RPM or 7200 is not used as a label switch controller (ie, with a BPX/IGX/MGX), these problems will not be seen. If either the RPM or 7200 is an LSC, there is a risk of these scenarios occurring in the field. LSC is not supported on Cisco IOS® Software Release 12.0ST.

Problem Description

The following catastrophic software defects affect MPLS and RPM users.

  • CSCdw47263 (MPLS)

  • CSCdw54940 (MPLS)

  • CSCdw59938 (MPLS)

  • CSCdw64740 (MPLS)

  • CSCdw67208 (MPLS)

  • CSCdw67882 (MPLS)

  • CSCdw80828 (MPLS)

  • CSCdw66983 (RPM)

  • CSCdw69707 (RPM)

You can view other MPLS and RPM defects using the Cisco Bug Toolkit (registered customers only) .

Problem Symptoms

The following displays the symptom and workaround (if one exist) for each defect.

`
CSCdw47263 (MPLS)
  • Symptom: Label bindings from an upstream router to a label switch-controlled ATM switch are not re-established when a downstream link failure occurs.

  • Condition: An XtagATM interface between two switches is shutdown. The output LVC of the upstream switch is deleted as a result of the shutdown. The input LVC is also deleted, however the upstream router connected to this switch is not aware of the loss of the label binding and thus does not attempt to request a new binding in order to re-route.

  • Workaround: Reset the TDP session between the upstream router and the switch by entering "shut/no shut" on the router interface.

`
CSCdw54940 (MPLS)
  • Symptom: Outgoing labels may become Untagged in TFIB when a TE tunnel goes down.

  • Condition: Between two label switching routers, LDP/TDP is configured on 1-hop tunnel and also on physical link. When tunnel goes down, outgoing label for a prefix reachable via physical link will become Untagged in some cases.

    Version Impacted: 12.0(20.3)ST3, 12.0(20.4)ST, 12.2(7.6), 12.2(7.4)T

  • Workaround: Executing "clear ip route " where A.B.C.D is IP address of the TFIB entry which has this problem.

`
CSCdw59938 (MPLS)
  • Symptom: A Label Switch Controller (LSC) will crash when an interface on a downstream router is shutdown.

    %ERR-1-GT64120 (PCI-0): Fatal error, CPU out of range error GT=0xB4000000, cause=0x0900E083, mask=0x0ED01F00, real_cause=0x08000000 bus_err_high=0x00000000, bus_err_low=0x10000004, addr_decode_err=0x00000470
  • Conditions: This issue exists on LSCs configured to use Tag Distribution Protocol (TDP). The output Label Virtual Circuit (LVC) is torn down as a result of the downstream interface shutdown. If the routing protocol hasn't converged, a new output LVC will be requested using the same interface to the downstream router. When the routing update occurs, the requested output LVC will be deleted and the input LVC will be released. When the input LVC is released, the LSC attempts to delete the output LVC once again, causing the crash.

  • Workaround: None.

`
CSCdw64740 (MPLS)
  • Symptom: tag-sw advertise-tags does not work when toggling between "tag advertise ..." and "no tag advertise .." for a TDP session. However it works for LDP session. The problem happens in 12.2(7.6)T and 12.0(20.3)ST3 releases.

  • Workaround: To recover from it, reset the TDP session by "shut/no shut" the interface over which TDP session is configured.

`
CSCdw67208 (MPLS)
  • Symptom: When BGP reallocates a new label for a VPN prefix LDP does not advertise the changed label to it's peers. Peers still have the old label for the prefix.

  • Condition : MPLS VPN Carrier's CArrier feature must be configured in a PE router with LDP as the label distribution protocol. The problem happens in the PE router where BGP changes the label but LDP running in the PE router does not advertise the label change to the CE routers.

  • Workaround: Clear the LDP session between the PE & CE. This can be done using "sh / no shut" of the VRF PE-CE interface.

`
CSCdw67882 (MPLS)
  • Symptom: mpls ldp explicit-null command does not work

  • Condition: TDP is running between two routers and "mpls ldp explicit-null" is configred. Explicit-null label will not be advertised by TDP. LDP does not have this problem.

  • Workaround: Use LDP in place of TDP or Reset the TDP session after configuring "mpls ldp explicit-null". Whenever above config is changed, TDP session will required to be reset.

`
CSCdw80828 (MPLS)
  • TDP may not advertise a tag in some situations. This happens when state of the a TIB entry changes from WITHDRAWN to ASSIGNED quickly. To recover from the situation shut/no shut the link whose network address is not advertised by TDP. Or reset the TDP session.

`
CSCdw66983 (RPM)
  • Symptom: rmbs under sw conn mode is missing from running or startup config, under certain circumstances, this will cause conn on PXM to fail and conn on RPM to mismatch.

  • Condition: Reload/reset the RPM card.

  • Workaround: Under 'sw conn mode' add the rmbs value manually.

`
CSCdw69707 (RPM)
  • Symptom: When an RPM sub-interface is shutdown, "snmpwalk" on PXM gives a wrong value for the admin status of the sub-interface

  • Condition: Shutdown RPM sub-interface, when RPM is used on PXM45

  • Workaround: None

Workaround/Solution

Workaround

See the Symptom section above for details on each defects workaround.

Solution

See the table below for details on each defects solution availability.

Defect ID

Cisco IOS Major Release

Cisco IOS Maintenance Release & Availability

Cisco IOS Interims & Availability

CSCdw47263 (mpls-lsc)

12.2T

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.2(8.5)T - Forecast Mar 11, 2002

CSCdw54940 (mpls-ldp)

12.2T

12.2

12.0ST

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.2(10) - Forecast May 6, 2002

12.0(21)ST - Forecast -Mar 18, 2002

12.2(8.5)T - Forecast Mar 11, 2002

12.2(8.4) - Feb 20, 2002

12.0(20.4)ST1 - Feb 28, 2002

CSCdw59938 (mpls-lsc)

12.2T

12.2

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.2(10) - Forecast May 6, 2002

12.2(8.5)T - Forecast Mar 11, 2002

12.2(8.4) - Feb 20, 2002

CSCdw64740 (mpls-ldp)

12.2T

12.0ST

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.0(21)ST - Forecast -Mar 18, 2002

12.2(8.6)T - Forecast Mar 18, 2002

12.0(20.4)ST1 - Feb 28, 2002

CSCdw67208 (mpls-vpn)

12.2T

12.0ST

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.0(21)ST - Forecast -Mar 18, 2002

12.2(8.6)T - Forecast Mar 18, 2002

12.0(20.4)ST1 - Feb 28, 2002

CSCdw67882 (mpls-ldp)

12.2T

12.0ST

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.0(21)ST - Forecast -Mar 18, 2002

12.2(8.6)T - Forecast Mar 18, 2002

12.0(20.4)ST1 - Feb 28, 2002

CSCdw80828 (mpls-ldp)

12.2T

12.0ST

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.0(21)ST - Forecast -Mar 18, 2002

12.2(8.6)T - Forecast Mar 18, 2002

12.0(20.4)ST1 - Feb 28, 2002

CSCdw66983 (mgx-rpm)

12.2T

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.2(8.5)T - Forecast Mar 11, 2002

CSCdw69707 (mgx-rpm)

12.2T

12.2(8)T1 - Forecast Mid May 2002

12.2(11)T - Forecast Late July 2002

12.2(8.6)T - Forecast Mar 18, 2002

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered leavingcisco.com user and you must be logged in.

DDTS

Description

CSCdw47263 (mpls-lsc)

tag bindings not established when re-route.

CSCdw54940 (mpls-ldp)

Packets get dropped due to incorrect tag info with exp-null on.

CSCdw59938 (mpls-lsc)

ERR-1-GT64120 Fatal Error.

CSCdw64740 (mpls-ldp)

NRT: bounce tag advertisment couse TFIB not poulate back case122.

CSCdw67208 (mpls-vpn)

LDP does not advertise BGP allocated label change during routeflaps.

CSCdw67882 (mpls-ldp)

MPLS LDP: explicit-null not advertised.

CSCdw80828 (mpls-ldp)

TDP may not advertise a tag in some situations.

rmbs under switch conn mode missing.

CSCdw69707 (mgx-rpm)

After shutdown rpm sub/f , snmpget admit status as up.

Cisco IOS Versions Affected

Defect ID

Cisco IOS Major Release

Cisco IOS Maintenance Releasee

Cisco IOS Interimse

Cisco IOS Images

CSCdw47263 (mpls-lsc)

12.2T

12.2(4)T

12.2(4)T1

12.2(4)T3

12.2(8)T

12.2(2.5)T though 12.2(8.4)T

rpm-*-mz

c7200-*-mz

CSCdw54940 (mpls-ldp)

12.2T

12.2

12.0ST

12.2(8)T

N / A

12.0(21)ST

12.2(7.4)T through 12.2(7.6)T

12.2(7.6) through 12.2(8.5)

12.0(20.3)ST through 12.0(20.4)ST

All supported platforms & images

CSCdw59938 (mpls-lsc)

12.2T

12.2

12.2(8)T

12.2(7)

12.2(7a)

12.2(7.4)T through 12.2(8.3)T

12.2(7.4) through 12.2(8.3)

rpm-*-mz

c7200-*-mz

CSCdw64740 (mpls-ldp)

12.2T

12.0ST

12.2(8)T

12.0(21)ST

12.2(7.6)T through 12.2(8.5)T

12.0(20.3)ST3 through 12.0(20.4)ST

All supported platforms & images

CSCdw67208 (mpls-vpn)

12.2T

12.0ST

12.2(8)T

12.0(21)ST

12.2(7.6)T through 12.2(8.5)T

12.0(20.3)ST through 12.0(20.4)ST

All supported platforms & images

CSCdw67882 (mpls-ldp)

12.2T

12.0ST

12.2(8)T

12.0(21)ST

12.2(7.6)T through 12.2(8.5)T

12.0(20.3)ST3 through 12.0(20.4)ST

All supported platforms & images

CSCdw80828 (mpls-ldp)

12.2T

12.0ST

12.2(8)T

12.0(21)ST

12.2(7.6)T through 12.2(8.5)T

12.0(20.3)ST3 through 12.0(20.4)ST

All supported platforms & images

CSCdw66983 (mgx-rpm)

12.2T

12.2(8)T

12.2(8.5)T

rpm-*-mz

CSCdw69707 (mgx-rpm)

12.2T

12.2(8)T

12.2(7.5)T through 12.2(8.5)T

rpm-*-mz

How To Upgrade Software

How to Choose a Cisco IOS Software Release

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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