10-30-2013 02:18 PM - edited 03-04-2019 09:27 PM
Hi,
How should I go about advertising a default route into the MPLS cloud? I want the MPLS/BGP provider to point all unknown traffic to the headend which is the path to the Internet for the sites.
I have a default route configured on the remote sites pointing at the MPLS provider neighbor.
See attached
Thank you
10-30-2013 02:24 PM
Patrick,
Under the bgp process on your headend router, you could put "neighbor
** Edit **
You'll want to make sure that you have a default route on the headend router pointing toward the internet though.
HTH,
John
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10-30-2013 02:49 PM
Thanks John
Yes there is an existing default route towards the Internet - the route points to the Core switches and from the Core switches to the Firewall.
So, the headend will still see a default route to the Cores after making this change? And the Service provider will then have a default route to our headend? And should be able to forward unknown routes accordingly?
Thank you, Pat.
10-30-2013 03:55 PM
Yes. It should work fine :)
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10-30-2013 05:07 PM
Pat,
I wanted to make sure I let you know that if you have static routes now for the default gateway on your remote sites, those will be preferred over your bgp routes. When you advertise your default from the headend router, go to one of the remote routers and do a "sh ip bgp 0.0.0.0". You should see a route that's bgp learned pointing to your ISP. Once you have that, it should be safe to remove the static if you're wanting to do that.
I would also recommend that when you remove the default route on one of the remotes, if you don't have a full view of your network and depend on default routes to get you everywhere, I would set the router to reload in case you remove the static and something happens with the bgp learned default route. In other words, if for some reason you remove the static default route and lose connection to the network, you can have a backout plan with a reload. Do a "reload in
HTH,
John
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11-01-2013 08:50 AM
Thanks John,
I will try it on one our sites that actually has a down time first with the reload command.
Couple more questions:
If there is an existing default route to the Headend configured on the remote router, will configuring the "neighbor
I currently have 2 default routes configured on the remote routers pointing to the provider. One is for the primary link and it has the default cost. The other is for the backup T1 link which is also using eBGP and it has a configured cost of 254 so the primary is preferred.
After I confirm the BGP default route is being advertised to the remote router from the ISP and after I delete the primary default route, will the ISP default route be preferred? I don't want my T1 route to be used unless the primary goes down.
On the other side of the remote routers are layer 3 switches that have a default route pointing to the remote router. I can leave that config, correct?
Hope that is clear
11-01-2013 09:49 AM
Pat,
When you advertise the default to the provider, the remote will learn the default route and it will still point to the provider. Your static route will stay in the routing table though since the ebgp learned route will have an AD of 20. There shouldn't be an outage that I can see. If you do a soft clear, you shouldn't have any interruptions, although to be on the safe side I'd do this config after hours. Another thing that you could do, if you already have a static route on the headend router, is to advertise that route under your headend bgp process with "network 0.0.0.0". Then you wouldn't have to clear the bgp sessions.
HTH,
John
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11-04-2013 10:49 AM
Thanks for your help John - applying it tonight.
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