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New Member

Multihomed to same ISP

We have two T1 connections to the same ISP. I would like to configure them to provide fail-over and load-balancing, ideally without requiring BGP. Our provider can simply provide static routes to each network over the separate T1s.

Each T1 terminates at a separate 2600 router with a separate /27 subnet, and each router has two fast ethernet interfaces. Would it be advisable to use HSRP, with an IP for each network on a separate fast ethernet interface? We also have a failover pair of PIX 515 firewalls with six behind these routers. How would you recommend I configure the static and default routes to make the most of our configuration?

Do you need any other information?

  • WAN Routing and Switching

Re: Multihomed to same ISP

Rather than HSRP, which does not do load balance, consider usign Gateway Load balancing protocol. This will allow you to load balance between the two T1s to your service provider. See below for more information on this protocol.

Re: Multihomed to same ISP

I assume the two outside (Internet) routers are connected to the outside interface of the PIX firewalls.

Since you want to get the best out of your setup, run OSPF on the PIX and the two outside routers. PIX doesn't load balance the traffic when static routes are used. However, with OSPF you can get the active PIX to load balance the traffic to both outside routers. Inject a default from both OSPF routers to the PIX with the same metric (cost). We have implemented this solution for some of our customers and it works great!!



New Member

Re: Multihomed to same ISP


i saw your posting and since I have the same issue now and am looking for solutions I was wondring if you can elaborate a little on this please. can you post the way the OSFP need to be configured on the PIX please? I have not done this before.