[squid-users] authentication with multiple proxies

[Stephen J. McCracken]

We have a couple of servers set up (RedHat 7.3, Squid2.5STABLE2) as
siblings with each having the other as fallback.  This is setup through
an automatic proxy script (proxy.pac).  We are interested in putting in
authentication (LDAP).  Is there any way to have a user login to just
one server and have the other accept the user as already authenticated
if they get switched to the other server?  Pointers to documentation or
manuals is fine.  Thanks!