configuring fallback parent

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Hi everyone!

We are currently in the process of creating a hierarchy of proxies at
our university. The idea is, to have one central proxy, which talks with
the outer world (i.e. higher levels in the german cache hierarchie), and
about one proxy per faculty. These proxies are siblings to each other, and
talk to the outer world only through the central proxy. This setup itself
is rather easy and causes no problems.

The question is: What happens, when the central proxy is not available?
We are searching for a clever method, to configure one of the siblings
as a fallback parent, that is only used as parent, when the central one
fails.

I came up with this: Every sibling (except S1) has this configuration:

cache_host P1 parent xxxx yyyy
cache_host S1 sibling xxxx yyyy
cache_host S1 parent xxxx yyyy no-query

So that S1 is usually not used as parent. But when we tested this, a lot
of requests from a sibling S2 were either requested as TIMEOUT_DEFAULT_PARENT
from S1, or as TIMEOUT_DIRECT from the original server. I would have expected
to see SINGLE_PARENT, or something similar. Especially, I did not expect so
many DIRECT fetches. So this does not seem to be the solution.

An other possiblity (though not a very "nice" one), is probably

cache_host P1 parent xxxx yyyy weight=10000
cache_host S1 parent xxxx yyyy weight=1

but we haven't tested this.

Are there any better solutions? I guess, we're not the only university,
that wants a setup like this.

What about a new tag "fallback" for the cache_host list?

- --
     Joern Clausen email: joern@TechFak.Uni-Bielefeld.DE

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Received on Thu Feb 06 1997 - 05:14:48 MST