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Packet discards question

After clearing the counters on a Cat 3508 earlier this morning, we've accumulated about 600 Total Discards as viewed from the Web interface. Upon executing the "show controller eth-cont gig 0/1" we noticed that we have about 400 no dest rev unicast and about 200 no dest recv multicast. Am I to assume that these are the incoming packets being dropped from my closet 2950 switch uplinks, as this switch sort of serves as a distribution switch for the building? Are these like an ICMP destination unreachables or similar?

Thanks in advance for any help.

1 REPLY
Cisco Employee

Re: Packet discards question

If I understand your description you have a 2950 distribution switch feeding a 3508XL. Is the link a trunk by any chance? Are there vlans forwarding traffic from the 2950 but do not exist (or have active ports in the vlan) on the 3508XL? This is likely the issue. Do you have VTP pruning (or manual pruning) enabled?

The counter is just indicating that the interface received frames it could not forward because it had no where to send them. This is not the same as ICMP unreachable. ICMP is for for Layer3/4 and sends messages back to the source. What you are seeing is Layer 2 only.

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