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Cisco Bug: CSCun63073 - FIB Manager Crashed - Fib manager Clean up and debug hardening

Last Modified

Aug 07, 2018

Products (7)

  • Cisco Carrier Routing System
  • Cisco IOS XR Software
  • Cisco ASR 9922 Router
  • Cisco ASR 9010 Router
  • Cisco ASR 9006 Router
  • Cisco ASR 9001 Router
  • Cisco ASR 9912 Router

Known Affected Releases

4.1.2.BASE 4.3.0.BASE

Description (partial)

Symptom:
fib_mgr[156]: %ROUTING-FIB-3-LEAF_DEPEND_CLEANUP_ERR : LEAF-DEL-ERR: All dependents of leaf 53f15bec did not unlink, leaf-ref-count:3 first-dep:53da1eb0

followed by:

Fib_mgr crash Signal code 1 - SEGV_MAPERR. Address not mapped. Accessed BadAddr 0x10 at PC 0x80f34dc.

Conditions:
Some churn in the routing tables casues a fib leaf to be updated, and for the dependants recursing through it to be updated too.  During the update of the recursive prefixes, an LDI is modified and this is rejected when being plassed to the PD code.  Some time after this the fib leaf is deleted, but there is a failure as the leaf still has dependants, which is not expected. This casues the generation of the initial error message.

We then fail to tidy up properly after we get into this state, and due to this at some later stage we crash as we dereference the table pointer in the path_list that is a dependant.  The delay between the initial errmsg and the crash is variable.

- We do not know the exact trigger for this, but it requires recursive prefixes, and it requires a platform LDI MODIFY failure.
- We do not know if it is limited to any specific set of platforms.
- We do not know if it is limited to any set of releases.

Related Community Discussions

IOS-XR: 再帰ルートの処理中に fib_mgr プロセスが crash する
2016年7月16日(初版) TAC SR Collection 主な問題 IOS-XR が動作する Cisco ルータ の FIB 上において、再帰ルートを含んでいるルート情報が大量にアップデートされると、まれに fib_mgr が crash することがあります。 その際は、以下の様なエラーメッセージが出力することが報告されています。 fib_mgr[156]: %ROUTING-FIB-3-LEAF_DEPEND_CLEANUP_ERR : LEAF-DEL-ERR: All dependents of leaf 53f15bec did not unlink, leaf-ref-count:3 first-dep:53da1eb0 fib_mgr プロセスクラッシュが発生すると、NP に対して、FIB 情報の再構築が完了するまでの間、該当 Line Card 上では通信断が発生します。 原因 この問題は <key>CSCun63073</key>として報告されています。 | <key>CSCun63073</key>: FIB Manager Crashed - Fib manager Clean up and debug ...
Latest activity: Jul 29, 2016
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