Unanswered Question

Currently I run 2 routers(7206) and a core switch(6509 acting as a vlan router/switch), BGP to two different providers and EIGRP internally. The 2 routers run HSRP and the switch points to a HSRP as the gateway.

Currently R1 is the primary router all traffic goes out 1 router. The other router was for backup in case the pri link went down. We are soon going to have to equal providers and I want to balance the traffic over both of them with BGP.

Is my thinking wrong that I would be better off using GLBP between the routers to accomplish this over HSRP?

I currently do not redistribute BGP to EIGRP but I have recently upgraded my 6509 with sup 720's so I know it could handle it. I am just not sure whether or not to use a high availability protocol or just let the routing protocols handle the switch over. In my mind GLBP would provide better uptime in case one or the other links goes down. But thats why I am asking as I could be very wrong.

Any help would be greatly appreciated.

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Edison Ortiz Thu, 03/13/2008 - 08:37
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If you want load-balancing on the first hop, you need to use GLBP as HSRP only has one router active at the time.

As for letting the routing protocol handle the switch over, well the first hop redundancy is there for end devices that have a single default gateway. The routing protocols provide no benefit to those devices as those devices do not learn routes.

How does the EIGRP speaking devices know how to reach the BGP routes?

Do the BGP routers announce a default route back to them?

Do you redistribute EIGRP to BGP?




Currently eigrp default route is set to the HSRP address, from there I get the BGP table and a default route from my two upstream providers.

I do not redistribute EIGRP into BGP.

Which ever router is the active HSRP is the router that traffic will go out.

I am padding my AS number on my secondary router so that the world prefs my R1 circuit into my network.

R1 has a 50Mb ethernet link

R2 has a Burstable DS3 that we pay extra for it use( it was designed as a backup link only)

BTW not my original design I just inherited it, so I am now trying to fix it.

The more I think about it having a high available protocol my not be best for this design anymore.

Edison Ortiz Thu, 03/13/2008 - 10:21
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Currently eigrp default route is set to the HSRP address,

How this default route is learned in EIGRP ?

Remember, EIGRP does not rely on HSRP but on the actual physical interfaces for router advertisement.

HSRP is used as a first hop redundancy for static routes on routers and default gateway on end devices.

Are you NATing in the BGP routers for your internal network ?

EIGRP is redistributing connected interfaces but the routers are learning the default route through BGP from the respective upstream provider.

I have customer networks attached to my 6509, Each customer is on a separate vlan with thier own IP space. I redistribute static and connect routes in EIGRP from the 6509, it's default route though points to the HSRP interface.

the Routers redistribute connected into EIGRP and announce the /21 ip space I get from my upstreams

the Routers also run BGP to the upstream and iBGP to each other.

so when customer sends data out it hops from the 6509 to the active HSRP router the out to the net.

hopefully I explained it well enough, I do not NAT any traffic in this part of my network.

James Lasky Thu, 03/13/2008 - 08:47
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I think you can get the benefit of using GLBP if the end devices are on the same network of 7206.

GLBP works very well when you have a lot of clients pointing to a destination...

But in your design I think you can get the benefit of route balancing just redistribuiting a default route from BGP to EIGRP from both 7206 with the same wheight.

If it helps pls rate




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