sh cef drop high Encap_fail counters on 6509

Unanswered Question
Aug 6th, 2009

I've been experiencing drops from the server network to clients intermittently.

doing a sh cef drop on the L3 switch that the servers are connected to the Encap_fail counters increase about 10 per second. Do I have a cef problem?

I'm on version 12.2(18)SXF13

I have this problem too.
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Laurent Aubert Fri, 08/07/2009 - 06:02


This counter means no ARP entry had been found for this IP packet. There are two root cause:

1- No answer to ARP request. Yo uwill see the cef entry marked as glean in this case

2- No ARP request send due to the throttling which protects the CPU in case of ARP request flooding.

To see if it's related, you should see if the MAC entries for your servers are stable. You could also check for any congestion point between the servers and the clients



rmoneal Fri, 08/07/2009 - 06:11

The mac entries are not stable. Even after pinging its IP successfully, the MAC address was not in the table:

Error: Destination Mac address not found.

Layer2 trace aborted.


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