Static Routing Failover With Multiple ISP's

[Ed Willson]

Hi all.  I have a new site, a new ISP and a couple problems.

Currently we have a MPLS network from provider A that links all our branches.  The branch HQ has the only access to the internet as well.  We're turning up a new site and utilizing a T1 that connects to the existing MPLS network, and a 100Mb MPLS link that connects the HQ and the new site only (at the moment). 

We are planning on migrating ISPs over the next year, so this is the first branch.  Everything was working okay using the 100Mb link with the new provider until I turned up the T1.  Once the T1 was up provider A started advertising a route to the new site via the T1.  So I need to get provider A to advertise the route to the new location via the HQ which will route to provider B.

Here's the problem.  I'm not very familiar with how the ISPs route traffic (both are using BGP).  I want to use the T1 as a failover interface if the 100Mb link goes down.  How should I communicate this need to both the ISPs if I plan on using IP SLA to test the connection from each side to make sure I have an up link?

Thanks,

     Ed

[Mohammed Alaradi]

Hi Willson,

i have quick skim to your post, does both links terminated on the same Router,

if yes, you can use IP sla along with static default route + change AD for static for failover.

Mohamed.

[Marwan ALshawi · Accepted solution]

can you provide som emore details

ok what routing are you using over the T1 and the new 100M MPLS link ?

you need to configure your routing in a way that it takes control of the failover no need to IP SLA unless youi are using static routing over both links

HTH

[Ed Willson]

Well the T1 is connecting to the established MPLS network that we're trying to move away from.  Curently all branches are connected to this network.  The new 100Mb link only connects the HQ and the new branch.  It seems like the problem I'm having is that both ISP's are using BGP to avertise our internal networks and the old provicer is advertising the new branch via the T1 and the new provider is advertising it via the 100mb link.  So if I ge the established provider to advertise the new branch via the 100Mb link via the HQ then what happens when the 100Mb link fails?  If I use IP SLA to send that traffic to the T1 the established ISP will be trying to route traffic to the new branch via the HQ still, which is now down.  So really I need to know if the ISP can advertise two routes with different weights and it one fails then begin to start advertising the new route....  I hope that makes sense....

[Ed Willson]

[Ed Willson]

After research into IP SLA failover on static links I enabled HSRP and got our carriers to switch to BGP routing. 

marwanshawi gets the point - but that's because it's the best answer that's not my own.

Thanks,

    Ed