NAT and AIM disconnects

[Peter Frischknecht]

In our latest network install, we decided to use NAT along with a combo
of DSL lines for the bandwidth.  The network is a very basic ethernet
network with capacity for 200+ users.  We are just starting out and so
far we have 80 users.

The bandwidth is provided with 2 DSL lines "bonded" using equal cost
routing to the 2.
Here is the setup for the gateway:

#ip routes
/sbin/ip route delete default
/sbin/ip route add default scope global equalize nexthop via 192.168.0.1
dev et
h2 nexthop via 64.192.154.166 dev eth3

#iptables
/sbin/iptables -t nat -F
/sbin/iptables -t nat -A POSTROUTING -o eth3 -j SNAT --to XX.192.154.165
/sbin/iptables -t nat -A POSTROUTING -o eth2 -j SNAT --to XXX.68.4.2


The network seems to run well.  There are no other noticeable problems,
except for AIM.  Most users complain of being disconnected from Instant
Messenger on a constant basis.
The gateway does not spit out any of its common "...out of
connections..." error notices.  My ip_conntrack_max is set to 48000.
The machine is a PPro200 with 256Mb RAM.

Does anybody else have the same trouble?
Do I need to do MASQUERADE along with SNAT?

Any help would be appreciated.

Peter Frischknecht
Empowering Solutions, Inc.
(888)5331949 x103
http://www.empoweringsolutions.com