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Configuration

I have a layer 3 3750 advertising its vlan interfaces via EIGRP to two routers. R1 and R2 connect to MPLS via 2 different carriers using BGP. R1 is the preferred path. My question is, how do I configure a default route for Core1 using EIGRP that will be aware of failures on either of these carriers.

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  • What is on the other end of the MPLS cloud? – Ron Trunk Jun 2 '15 at 20:11
  • Hub center with a connection out to the internet. – HAL Jun 2 '15 at 20:54
  • Hal, are these WAN connections using public or private IP addresses? – Ronnie Royston Jun 2 '15 at 20:56
  • Public addresses. – HAL Jun 2 '15 at 20:59
  • Ok, do the routers receive a default route from the other end of the cloud? – Ron Trunk Jun 2 '15 at 21:07
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Perhaps you could investigate using ip sla for your needs. These links may not be exactly what you are searching for but it could help with searching on ip sla.

http://www.ciscozine.com/using-ip-sla-to-change-routing/

https://paulbeyer.wordpress.com/2013/09/14/configuring-cisco-ip-sla-and-object-tracking/

http://www.geekmungus.co.uk/cisco-and-networking/failoverinternetconnectionusingipslatrackingandeigrproutingforinter-sitelinks

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We advertised a default originate out of our home location to the remote sites. As long as the carrier is advertising routes, the routes will be preferred from the mpls branches.

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You can't achieve the function you want with just a default route on Core1.

You might inject BGP routes within EIGRP on routers R1 & R2, and define a different weight to these 2 EIGRP neighbours at the Core1 level.

If either R1 or R2 fails or their BGP neighbour fails, then all the traffic will use the remaining one once EIGRP will have updated its routes table.

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  • Any example configs? To my knowledge you weigh the bgp routes when redistributing into EIGRP on the routers. This doesn't solve the default gateway problem unless there is a router somewhere in the MPLS that is advertising default-originate. – HAL Jun 2 '15 at 19:21
  • I'll try to route 3 questions at a time :). Sorry no. You can do it this way too, but its easier to manage the weighting on just one router (Core1). You don't have to have a default gateway: at a given time network A will be routed through R1, and network B through router R2. – dan Jun 2 '15 at 21:43
  • How does the router learn where to send internet bound traffic through the MPLS? The MPLS has no direct connection or BGP route for the internet. – HAL Jun 3 '15 at 19:55
  • For BGP to start running on your R1 & R2 routers, R1 and R2 need just one 1st route. This isn't a default route, this a route (rather 2) to reach your neighbour BGP router on your 2 ISP. Hence BGP will be correctly feeded by your 2 ISP with the whole routes set to the Internet. – dan Jun 4 '15 at 6:57

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