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Multihoming with Cisco 3640 router questions

I currently have a Cisco 3640 router and 3 T1's in a multilink PPP configuration from my primary ISP.  I recently added 2 T1's also in a multilink PPP configuration from a secondary provider.  I obtained an ASN and we configured BGP to run over the MLPPP interface with both providers.  I am receiving default routes from both ISP's

I have 2 class C address blocks and 2 partial address blocks from the primary ISP.  I want to configure the router to send traffic on the 2 Class C blocks thru the secondary provider upon failure of the first.
The secondary provider is configured to allow me to announce the 2 class C's thru their network.

The first thing I am not sure of, is if the Cisco 3640 router is capable of doing this efficiently, because if it is not, I need to figure out what router (that I can afford thru ebay ;) ) I would need.

If this router is capable, I am not sure how to configure the BGP session to do this.

I would also appreciate an explanation of any code because while I understand basic cisco programming, we are entering an area where I don't understand the commands and what they specifically do internally.  I'd like to understand that.

Thank you for your time!
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Steve
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I do the same thing there but with 7200's..

two seperate links from ISP's coming into 2 x 7200's.. running BGP for all our class C's.. we run OSPF internally as well, and have setup HSRP with iBGP between the two 7200's for failover, so that we have a 'primary' ISP and upon failure we cut over to our secondary ISP..

it all depends on your ISP's though and how they configure / want to configure you.. you'd probably have to use AS prepending to prioritize your paths.. or perhaps communities preferencing.. depending again on your ISP..

as for the 3600's.. we havent had them for many many years.. i remember we used to run BGP and OSPF on them, but had a lot of issues with bgp tables filling the memory on them.. id be recommending upgrading to better routers..

Good luck with it !
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USGRobocoder

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Thank you for the input, however, I may not have asked the question correctly (my first time using this service).  I am looking how to write the code to do the multihoming/failover.

Thanks!
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Then on your interfaces you have something like ;


interface GigabitEthernet0/1
 <snip all normal stuff>
 standby 10 ip <Virtual IP address within same subnet>
 standby 10 priority 150
 standby 10 preempt

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