default gateway does not allow to get connected to the internet
 

Dear all,
i am facing a problem in my network. let me explain...

i have a leased line ( speed 2 MB ) which we use to connect to our mail server , oracle ERP etc.. we have a dhcp scope defined as 192.168.100.1-192.168.101.254. with a default gateway as 192.168.100.90 ( which is a cisco router ) we have a pix firewall ( 192.168.100.10 ).. now the gateway passed all the request to firewall..
we have an ADSL of 4 MB speed.. ip is 83.*.*.230 from ISP. i have a proxy server ( squid ) eth0 is connected to ISP (83.*.*.230).. eth1 to LAN ( 192.168.100.79 ) now the problem is when i put default gateway to eth1 ie 192.168.100.90 the squid connects to internet via leased line.. if i leave the default gateway field empty on eth1 , the squid connects to internet via ADSL ( which i want ) but the problem is no one on the lan cant ping the squid server ( no connectivity to internet for the whole LAN ) how can i solve this problem?

PS : i want squid to connect to internet with ADSL, but if i put gateway on eth1 ie LAN squid goes through leased line which i dont want to happen. i appreciate any help in this regard. i tried all possible ways...

hi,
is it any firewall block against your access to leased line Your pix on which line