Re: [squid-users] IPC <-> round-robin

Van Bossche Koen wrote:
>
> Hi,
>
> Can someone explain me exactly why it is not adviced to use IPC and
> round-robin together. What are the PRO's and CONTRA's of both?
>

These are different ways of doing the same thing, figuring out
what neighboring cache to forward MISSes to.

Round robin chooses a next cache by going through the complete list of
cache_peers over and over again. That sheds load, but has poor latency
and fault tolerance.

ICP has the cache make a request to each neighboring cache as to who
has a copy of the object before deciding where to send the MISS. That
is a bad system because you have to wait for ICP responses.

The best current choice for most cases is probably to use Cache Digests,
a system in which cache_peers tell each other in advance what is
and what is not in their caches. That gets many of the advantages
of ICP without the nasty latency hit. To get this, include
--enable-cache-digests as an argument to ./configure.

-- 
Jon Kay        pushcache.com                      jkay@pushcache.com
http://www.pushcache.com/                             (512) 420-9025
Squid consulting, installation, maintenance        'push done right.'