LARTC - Jul 2004 - Squid - Load Balancing Multihomed Linux Router

Hi All,

In a scenario, where a LAN is being provided internet connectivity 
through multiple ISPs terminated at a Load Balanced Multihomed Linux 
Router as described in LARTC HowTo, how would the traffic distribution 
affected if there is a squid based transparent proxy for the LAN''s web 
traffic on the same system (i.e. the load balanced router itself). The 
recent squid versions have an option of setting multiple values for 
"outgoing_tcp_address" depending upon various ACL rules. Its also 
possible to not specify any IP address for this parameter so that it 
takes the outtgoing address on its own. But how would the proxy server 
behave in case of 2 or more outgoing internet links ? Has someone tried 
out something similar ? What will happen if this transparent proxy 
server is on a different system within the LAN itself ? Would the 
traffic distribution between multiple ISPs be affected since the entire 
web traffic would appear to originate from a single LAN IP (the IP 
address of the proxy server) ?

Thank you in advance for your comments.

- Manish

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Manish wrote on 06/07/2004 15:01:58:
> [...]. But how would the proxy server 
> behave in case of 2 or more outgoing internet links ? Has someone tried 
> out something similar ? 
you will have problems with sites that keep track of IP addressess for 
session validation.  Some sites will end the session if they receive a 
request from a different IP than the one that initiated the browsing. This 
occurs mainly in banks and other ssl connections.  Here, I use a iptables 
mangle rule to mark tcp/443 packets and a ip rule to direct marked packets 
to one fixed link.
> Thank you in advance for your comments.
> 
> - Manish
> 
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