Re: [squid-users] WCCP and Web Cache Packet Return

From: Amos Jeffries <>
Date: Sat, 08 Nov 2008 00:04:03 +1300

Bin Liu wrote:
> Hi,
> Just read the WCCPv2 document from
> It seems that WCCPv2 support web caches tunneling back the packets
> they do not service to the same router from where they are received.
> Once a router has received a formerly redirected packet, it knows not
> to redirect it again. Here is the details:
> Web Cache Packet Return
> WCCP v2 filters packets to determine which redirected packets have
> been returned from the cache engine and which ones have not. It does
> not redirect the ones that have been returned because the cache engine
> has determined that the packets should not be cached. WCCP v2 returns
> packets that the cache engine does not service to the same router from
> which they were transmitted.
> So can current version of squid support the following features:
> 1. Sending the packets squid can not service back to router via GRE
> tunnel or Layer 2. There are many applications just "borrow" the port
> 80 and send their own formatted data, they are not HTTP requests at
> all. Currently squid will only report a "clientTryParseRequest: FD 41
> (x.x.x.x:xxxx) Invalid Request" error in cache_log when receiving
> these packets.
> 2. Sending packets back according to the ACLs defined in squid.conf.
> So when customers access some domains or URLs, the request packets can
> be returned back and then go out directly. A bit like the
> redirect-list defined on router, but we can't write domains or URLs in
> router's access-list.
> I've noticed that there are some keywords like "wccp2_return_method"
> in squid configuration directives. Is this just to be compatible with
> WCCPv2 communication protocol or can be fully functional?

WCCPv2 is supported in all current Squid (2.6+, 3.0+)

The squid just needs to be built with --enable-wccpv2


Please be using
   Current Stable Squid 2.7.STABLE5 or 3.0.STABLE10
   Current Beta Squid
Received on Fri Nov 07 2008 - 11:04:08 MST

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