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Wrong UDP port in WCCP

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  • Wrong UDP port in WCCP

    Greetings, forum members!

    I've encountered a very peculiar problem at one of our customers' site, and I was wondering whether anyone can shed some light on it.

    The customer is using a CAT 4948 switch, and he's got our product connected to it, working as a WCCP cache engine (L2 forwarding, MASK assignment). We use UDP port 2048 in order to communicate with the switch via WCCP, and we connect from a random source port (hoping, obviously, to receive any answer on the same port). However, once in a while the switch starts calling us on a different UDP port. I am attaching a small capture that demonstrates this exchange. In it you can see our device with IP and the switch with IP We use source ports 1267,1268 and destination port 2048, whereas the switch uses source port 2048 AND destination ports 2639, 2640.

    After a reset, the switch goes back to using the correct ports. Any idea anyone what might have caused such a behavior?
    Attached Files