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Thursday, December 8, 2011

Duplication packet occured on Catalyst 4507R+E

What does the message below mean?This log message is produced Catalyst4507R+E.The device is inserted SUP-7 with 3.1.0SG Image.With this log message, the device produced duplication packet of multicast.
Dec 2 16:40:00.276: (Suppressed 269 times)Dup Packet Fail for Sw Port

The message "Dup Packet Fail for Sw Port" is seen when certain multicastpackets are software bridged and software has run out of buffers whilereplicating the packets in software.In typical deployments, one should NOT have a lot of multicast packets to CPU. Could you check what iscausing multicast packets to CPU periodically? Can you get the output of"show platform cpu packet driver" ? This could provide a hint as to packets drops due to high incoming rate to CPU. It can be normal situation as some multicast should come to CPU to build all records, so depending on the mcast groups number sometimes buffers can be filled. So you can Change the logging level to '5' not to see that message. Other possibility is that you get Multicast packets with TTL expired (TTL=1) thus those punted to CPU and dropped there. For this sniffer should be done on mcast ports to check mcast packets.

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