• Author : Manasee Joshi

 
 

Troubleshooting Egress Queue drops on 7280/7500 devices

Aggregate VoQ drops on 7280/7500 devices On 7280/7500 devices, the platform architecture uses Virtual Output Queuing (VoQ) between the ingress and egress chips to forward known unicast traffic. Whenever a packet is to be transmitted, the ingress chip requests for credit from the egress. Once the credits are issued/granted, the packet is dequeued to the egress chip. While the packets are awaiting the credit, they are enqueued on the ingress chip buffers, in the Virtual Output Queue (VoQ) for the corresponding egress port. Accordingly, in the output of “show interfaces counters queue detail” on these devices, we see two sections:...
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Troubleshooting Dequeue deletes on 7280/7500 devices

Overview On a 7280 / 7500 devices, any known unicast packet which arrives on an ingress port is classified by the ingress processor based on priority level and egress port, and enqueued in the Virtual Output Queue (VOQ). The same would apply for BUM traffic if ingress only replication is enabled. The packet is enqueued on the ingress chip buffers until the egress packet scheduler issues a credit grant for the given packet. DeqDelete drops indicate stale packets in VOQ, i.e, packets which have been in the VOQ for more than 500ms without getting credits. These packets are deleted, and...
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