the efect of the static route on incoming traffic through another interface

gentianhila · ‎03-05-2008

Soon we will have a second T1 line from a different ISP (multihomed network). In a matter of few months we will switch both of lines to the new provider, but in the mean time since we cannot do load balancing through BGP we were thinking to use the old one for some types of incoming traffic through DNS records. I am thinking to configure the router with only one static route to the new line. By the way, we will be utilizing only half of the old T1 for data so I don't want to have two static routes as they will split the traffic in half between two lines and the new T1 will have all 24 channels for data so it should carry most of the traffic.

Anyway, my question is:

I will have traffic coming from old T1 into our network. The traffic that is sent as a reply to these request, is it going to go out through the old T1 or will the static route diverse it to the new T1. How can I make sure the later does not happen?

Richard Burts · ‎03-05-2008

Gentian

There are some aspects of your explanation that I do not fully understand. But one thing is clear. If you have 2 T1s that receive traffic and you have only 1 default route to direct outbound traffic then all outbound traffic will use the new T1.

If you can identify that traffic (if it used DNS to find the way in then perhaps you can identify the addresses that it came to) then perhaps you can do Policy Based Routing to send the response traffic back out the old interface.

HTH

Rick

HTH

Rick