Matus UHLAR - fantomas wrote:
For me ICPs only use is that it allows the clients to load-balance based on response time from the servers. (all queries to all servers?) All the external traffic must pass through the squid-s anyway.
along with cache digests, ICP can be used to detect if one of siblings has object in its cache. That's why I recommend using it.
The setup in here is that all the external traffic always goes through the external proxy.
So it does not make any difference and in case of a parent cache hit it will save some ICP queries.
We have no CPU cycles to waste :(
Now I am starting to think, that if the queried parent squid will ask with ICP from other parents/siblings anyway, then what is the real difference...
see http://squid.visolve.com/squid/squid24s1/glossary.htm for difference between parent and sibling.
If you have more 2nd-level squid caches with different links, you probably should set up them all as parents to your 1st-level proxy and as siblings to each other (just for sure) and set up ICMP on all of them to be able to know which proxy is closest to the requested data and fetch the data using that parent.
Yup, that is what I am doing at the moment.
Two things are different:
in case of a direct parent cache hit (>90%) no ICP queries will be sent to other parents.
in case of cache miss the is a delay to ask from other caches.
Juhani
