Re: WCCP - cache only , no proxy

Lincoln Dale wrote:

> while it wouldn't be impossible to do this, and take the hit of maintaining
> all that per-flow state information in a switching device (can you say:
> "doesn't scale"?), it would break spectacularly if you had assymetric
> routing or redundant paths that traffic can take back to the end-user.

So does WCCP, or any other redirection techniques. If the traffic flow
not always passes by the redirection point then you are screwed.

Another interesting reason to not use redirection was brought up on WREC
recently, namely IP fragments. The reassembly of IP fragments relies on
that the sending host manages the IP fragment namespace correctly, which
probably won't be the case if you are talking to two hosts with the same
IP (i.e. the cache and the origin server, or the cache and the client
when the cache is masquerading as the client).

In the long run "transparent" proxying is a dead end. Other means of
directing the users to the caches must be found. WCCP and other
redirection techniques should only be seen as a bandaid until these
other means are found and ready for deployment.

--
Henrik Nordstrom
Squid hacker