BGP Mutihoming (Load Balancing)

Posted on 2007-04-04
Medium Priority
Last Modified: 2013-12-24

We are building a new datacenters and in each datacenters we have mutiple connections out to the outside world. we are planning to use private AS provided by our ISP, so we will have IBGP full mesh on our internal routers and peer up with our ISP Public AS. We will redistributes routes in to IGP (EIGRP) and then routing decisons  towards the internet will be made by EIGRP. My question is, does it make any difference if we get a full routing information from the ISP or partial or just a default route.  My personal decision is i dont think we need a full routes (120,000 routes) becaus this put more load on our IBGP routers and also redistributes in to EIGRP will also cause issues. (Too many routes to manage).  Please advise.

and thanks in adavance guys......

Question by:backbonemd
LVL 28

Expert Comment

ID: 18853478
If you can think of a scenario where having a specific route via one path would be preferable to following the default route via another path, then you might want to receive the full routing table, and use a route map to reject everything you don't care about (everything but that specific route and the default).

But in most cases, following the default route is fine and you probably don't need more than that.
LVL 12

Accepted Solution

pjtemplin earned 500 total points
ID: 19247125
Will you have multiple links to the same provider, or multiple providers?  If it's the same provider, private AS is fine.  If it's multiple providers, you'll likely need to get an AS number.  They're relatively inexpensive, especially compared to the cost of a datacenter.

Don't even think of redistributing BGP routes into an IGP - your network will melt.  Use the IGP to give reachability between your routers, and use BGP to carry the external routing information to your routers.  Full routes is 215,000 routes and growing - be sure your routers (if Cisco) have 512MB of RP RAM and 256MB of linecard RAM, or you'll likely have major problems.

Taking full or partial routes gives you more control over your outbound routing.  It's typically challenging to get multiple 0/0 routes functioning in parallel.

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