[squid-users] Squid forgetting originservers when box has several IPs

Hi!

I use Squid for years now as loadbalancer and accelerator.
Lately our ISP decided to replace the whole IP range we use. To ease
transition we were given a two months period in which the old and new
IPs are working the same time.

As soon as we start using the second IP on our proxy server, and restart
squid to bind to the new interface too, squid serves some requests, then
  decides that the originservers are gone.

cache_peers are apache2 webservers so instead of ICP requests they got
udp echo requests. They get some UDP packages (checked with tcpdump),
but when they disappear, they do not get echo requests, and they wont
come back.
If I replace the 7 (udp echo) with 0 for ICP port in the cache_peer
line, squid works, but do not notice weather the server is up&running or
not.

I use: Squid 2.6.5 (default Debian/Etch binary)
config and log is attached.
If I need to provide anything else, please let me know!

Detailed (debug) logs shows, that the first few requests have parents:
2007/06/28 13:44:23| peerGetSomeParent: GET www.aexample.com
2007/06/28 13:44:23| peerSelect: FIRST_UP_PARENT/Y.Y.Y.Y
2007/06/28 13:44:23| peerAddFwdServer: adding Y.Y.Y.Y FIRST_UP_PARENT
2007/06/28 13:44:23| peerAddFwdServer: adding Y.Y.Y.Y ANY_PARENT
2007/06/28 13:44:23| peerAddFwdServer: adding Y.Y.Y.X ANY_PARENT
[...]
2007/06/28 13:44:26| peerSelectFoo: 'GET www.example.com'
2007/06/28 13:44:26| peerSelectFoo: direct = DIRECT_NO
2007/06/28 13:44:26| peerDigestLookup: peer Y.Y.Y.Y
2007/06/28 13:44:26| peerDigestLookup: gone!
2007/06/28 13:44:26| peerDigestLookup: peer 81.2.252.112
2007/06/28 13:44:26| peerDigestLookup: gone!
2007/06/28 13:44:26| neighborsDigestSelect: choices: 0 (0)
2007/06/28 13:44:26| peerNoteDigestLookup: peer <none>, lookup: LOOKUP_NONE

Thanks in advance!
        Peter Siklosi

visible_hostname www.example.com

http_port 80 vhost defaultsite=www.example.com

cache_peer Y.Y.Y.Y parent 80 7 originserver no-digest weight=3
cache_peer Y.Y.Y.X parent 80 7 originserver no-digest weight=5

acl hammerers src 193.28.86.0/255.255.255.0
acl all src 0.0.0.0/0.0.0.0

http_access deny hammerers
http_access allow all

# emulate_httpd_log on
cache_log /var/log/squid/cache.log

cache_dir ufs /home/squid 20000 128 256
cache_access_log /var/log/squid/access.log
cache_mem 1200 MB
maximum_object_size 8 MB
maximum_object_size_in_memory 2 MB
cache_replacement_policy heap LFUDA
memory_pools on
memory_pools_limit 400 MB

error_directory /usr/share/squid/errors/Hungarian