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Cisco Bug: CSCvs82183 - TTL=1 traffic over vPC peer-link with l3 peer-router enabled punted to software.

Last Modified

Oct 29, 2020

Products (2)

  • Cisco Nexus 9000 Series Switches
  • Cisco Nexus 9000 Series Switches

Known Affected Releases

9.2(3)

Description (partial)

Symptom:
1) In a vPC setup, layer-3 packets with TTL set to1 and destined to the peer switch (switch-B) are delayed or dropped by Switch-A.
vPC config has 'l3 peer-router' enabled.

2) Elam has Sup hit flag set and DI as Sup index.

L4 Protocol  : 89
Sup hit: 1, Sup Idx  : 3511

3) CoPP has huge count under ttl exception class.

    class-map copp-system-p-class-exception-diag (match-any)
      match exception ttl-failure
      match exception mtu-failure
      set cos 1
      police cir 150 kbps , bc 32000 bytes 
      module 1 :
        transmitted 187005366349 bytes;
        dropped 4725576043564 bytes;

Conditions:
packet must have TTL = 1
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