Cisco Bug: CSCta06502 - [39-CRS-FIT] mpls_ldp crash when feature unconfigured
Jan 28, 2017
- Cisco Carrier Routing System
Known Affected Releases
Symptom: LDP crashes after LDP config was unconfigured, with NSR and GR enabled. Conditions: Crash occurs because LDP asserts when peer is release because it's on the NSR delay list. Peer should be removed from list when peer goes down, so it shouldn't be on list when peer is released. The peer ended up on the list as a result of the following sequence of events: 1) NSR unconfig is applied. The global NSR config flag is cleared and async event is enqueued to process the unconfig event later. 2) GR unconfig is applied, resulting in sessions going down. Since NSR config flag is already cleared, NSR processing is skipped and the peer NSR state doesn't transition to NONE state. 3) IPC disconnect is received from standby LDP resulting in peer transitioning to WAIT state and being added to NSR delay list. NOTE: If peer NSR state was in NONE state when IPC disconnect was received, peer would have been skipped and would have not transitioned in WAIT state. 4) Peer is released and LDP asserted because NSR delay list was not empty. NOTE: LDP asserted before NSR async event was received and processed. If NSR async event would have been received before peer was released, obviously crash would not have happened.
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Bug Details Include
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