Two ISPs load sharing.

[jbahm]

I am in the process of adding a second ISP for my internet connection, what would be the best approach

to load share the outbound data between the two ISPs?

[gabrieloyeyemi]

The best approach is to use the BGP (Border gateway configuration). This involves acquiring an autonomous system from Ripe NCC and also ensuring that the two isp have an autonomous system. This way you can control both inbound and outbound traffic. If you need a sample config, don't hesitate to contact me for further information.

Gabriel.

[Richard Burts]

I think that the answer depends on how you define "best". For some people best is the simplest, the easiest to support, the least likely to break and require troubleshooting, and with the least overhead. For these people the best answer is a pair of default routes, one pointing to ISP A and the other pointing to ISP B.

Other people define best as the most sophisticated, the most powerful, providing the most control over traffic. For these people the best answer is probably running BGP.

So perhaps John can tell us how he defines best and we can figure which solution that leads to.

HTH

Rick

[jbahm]

Thanks for the reply.

Best for me means, most reliable. I am eliminating all of the single points of failure. With the addition of the second ISP I hope to share the bandwidth on the outbound path, and have ether path run the full load in the event of a failure.

I don’t need a perfect 50:50 split, I just don’t want the new bandwidth waiting for a failure to be used. My outside firewalls are a pair of HSRP PIXs. It would be good if the PIX could do the load sharing, but it only supports OSPF.

[ankurbhasin]

Hi ,

I think if you are not using BGP the best solution for you will be to use 2 static routes with different administrative distance......one static route with distance as 1 and other could be with 2..and it will definetely take care of your failure scenario.

[Richard Burts]

If you define best as most reliable, then I think that the simple approach of two static routes is probably the most reliable. There is certainly less in that to break than there is in running BGP. The static routes should allow you to do some load sharing.

Perhaps you can tell us a bit more about the topology of your network. Especially will both ISP connections terminate on the same device? And is the terminating device your firewall or a router?

HTH

Rick

[steve]

You will also need at least a /24 to advertise to your providers and a router/IOS capable of running BGP. I usually suggest a 3600/3700 with 256MB of DRAM for two full tables and soft inbound.

Regards,

Steve

http://www.cisco-forum.com

[amitbatra]

hi

well u can add to default route without changing the ad.u just enable the fast switching on ut equipment. coz fast switching willl enable the per destination based load sharing. where as normal routing does the per packet load balancing.hope this help u out.

[jason.aarons]

I recommend letting BGP determine the shortest AS-PATH rather than trying to force a equal load.

[steveo123]

Most ISP’s will not allow BGP peering with the CPE, its just another overhead on there border routers, and also I assume you do not have a point to point link with them which also means unstable TCP port binding with BGP session, inadvertently causing BGP flaps. Just add two equal metric default routes and run RIP v2 or a protocol that meets your needs.

Regards,

Steve