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Cisco Bug: CSCvi91299 - OTV process hang or crash post Overlay peer going up or down

Last Modified

May 24, 2019

Products (9)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch
  • Cisco Nexus 7700 2-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch

Known Affected Releases

7.2(1)D1(1) 7.3(2)D1(2)

Description (partial)

This fix is addressing following issues:

1) OTV process Crash due to heartbeat failure on releases without CSCuy89746.
    after interface of peer in Overlay went down or up (reload, shutdown, etc.)
    This is day0 issue and affects all NX-OS releases with OTV functionality.

2) OTV process Hangs in releases with fix CSCuy89746 (for example 7.3(2)D1(2))
    after interface of peer in Overlay went down or up (reload, shutdown, etc.)

OTV process Hang is a state where device cannot maintain OTV Adjacencies, 
"show otv <>" commands don't work, show tech otv doesn't collect, tacpac doesn't
collect, and MTS buffer queue builds up.
Only recovery from this state is either supervisor switchover or process kill by TAC using
debug plugin.

Problem is seen under those (statistically low likely) circumstances:
- First 2 bytes of Site ID on OTV Edge node extending same VLAN are not 
  0x0000 (yyyy.0000.0000 where yyyy not equals 0x0000)
  For example eeee.0000.0001 or 0009.0009.0009, etc.
- VLAN's value in reversed octet order hexadecimal is lower than first 2 bytes of above Site ID
- VLAN is is the last VLAN processed in VLAN loop (order of VLAN processing not really predictable,
  not based on config order or VLAN value)
- Trigger for problem is flap of OTV Join interface of any node which is part of same Overlay
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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