Use digests between 3 siblings on a fast network?

Hi,

We have 3 caches which each have two 100FDX interfaces... one side
connects them to the campus network (for client requests and connections
to our parent caches and origin servers) and the other is a private
fully-switched segment purely for inter-cache traffic.

Is it worth using cache digests *between* our caches [they have a sibling
relationship with each other]? (We do already with the parents.)

We're using 2.2stable4 (on Solaris 2.6). Our servers are not [currently;
this may change after term restarts] heavily loaded.

Thanks,

  - Bob

-- 
 Bob Franklin <r.c.franklin@reading.ac.uk>     Tel. +44 (0)118 931 8432
 Systems and Communications, IT Services, The University of Reading, UK