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Cisco Bug: CSCvs62217 - Upon upgrading/reloading ASR920 traffic loss is observed at the Egress side.

Last Modified

Aug 29, 2020

Products (1)

  • Cisco ASR 920 Series Aggregation Services Router

Known Affected Releases

15.6(1.2)

Description (partial)

Symptom:
Upon upgrading/reloading ASR920 traffic loss is observed at the Egress side.

Conditions:
This is an issue in egress TCAM programming for Qos. For the Qos to work, the Qos configurations will be programmed in the TCAM memory. Each policy-map will have its own TCAM memory and so when a packet matches a TCAM entry based on the match conditions (class-map), the TCAM will be hit and the packets will be subjected to the resultant actions from the TCAM (like set actions, policer, shaper etc) from the policy-map. In this case, packets entering the Poch64 was properly hitting the ingress policy-map and all the set-actions was also given to the packets, however in the egress pipeline for the egress policy-map to be matched, there was a mishit. Instead of hitting the TCAM entry for the egress policy-map in the egress interface gi0/0/0 & gi0/0/2, it was hitting a different TCAM entry.

This different TCAM entry in fact is a wrong entry programmed in the Hardware and it is a corrupted one. Therefore all the packet were dropping or trying to egress out of that interface from where the corrupted entry is programmed.
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