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Cisco Bug: CSCvv70929 - NXOS: MFDM service crashes in mfdm_fib_process_v4_route_response

Last Modified

Oct 28, 2020

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

9.3(5)

Description (partial)

Symptom:
A Cisco Nexus datacenter switch may experience a service crash within MFDM on the supervisor due to a signal 11 / segmentation fault. In some cases, multiple crashes within MFDM may trigger a HA reset and bring the supervisor down (or cause a failover). 

%$ %SYSMGR-2-SERVICE_CRASHED: Service "mfdm" (PID ####) hasn't caught signal 11 (core will be saved).

Conditions:
This is seen in highly scaled multicast environments and some conditions associated to this crash are:

1) This is seen only if L3 multicast is in use. 
'feature pim' is configured

2) MET exhaustion is observed in the logs. In this example, MET exhaustion was seen across multiple linecards because a portchannel was being used as an OIF.
VDC-1 %$ %IPFIB-SLOT4-2-MET_INDEX_RESOURCE_EXHAUSTION: Met table is exhausted on this LC.
VDC-1 %$ %IPFIB-SLOT3-2-MET_INDEX_RESOURCE_EXHAUSTION: Met table is exhausted on this LC.
VDC-1 %$ %IPFIB-SLOT2-2-MET_INDEX_RESOURCE_EXHAUSTION: Met table is exhausted on this LC.
VDC-1 %$ %IPFIB-SLOT1-2-MET_INDEX_RESOURCE_EXHAUSTION: Met table is exhausted on this LC.

3) OIFs limit being exceeded across a large number of sources. 'show ip mroute summary' may display a multicast group showing large source count with a large number of OIFs per each source.

Group: <multicast group address>/32, Source count: 2480 <----
Source          packets      bytes           aps   pps       bit-rate     oifs
(*,G)           58187        10306952        177   1         2.601   kbps 113 <----
<source addr>   22           1232            56    0         54.400  bps  115  
<source addr>   0            0               0     0         0.000   bps  115
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