Дима Рубинштейн (dimrub) wrote in gotchas,
Дима Рубинштейн
dimrub
gotchas

WCCP in mask mode - constant source ports

Problem: A WCCP router stops monitoring a service after the client has been restarted

Analysis: Certain Cisco routers remember the UDP source ports, and answer back to the ports they remember - instead of answering on the same port that the datagram came from. There are reasons to believe Cisco only use source port 2048 in their client (and perform services demultiplexing by looking at the content of the packet itself).

Solution: Perform access to the router from a constant source port. Take care of multiple routers and multiple services - perhaps, the source port should be constant per any combination of the above.
Tags: cisco, networking, wccp
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