[c-nsp] OSPF and BGP relationship

[Aaron]

I also have 2 (working on 3) Internet connections and only learn default route from upstream provider....

I don’t know if this is best/common practice but if I ever prefer a /32 to exit out one of my particular internet connections, I'll point a static /32 out that internet connection and redistribute it into my igp....my igp happens to be mb-ibgp for my l3vpn's to rcv it across my mpls network.

Aaron

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of CWO Network Operations
Sent: Monday, March 02, 2015 3:40 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] OSPF and BGP relationship

I have a question about the common practice of using OSPF and (i)bgp.

Here is my setup:


I have 4 Cisco routers (A, B, C & D). All routers are connected to each other through metro ethernet connections. The 4 routers have other “stuff” behind them speaking only OSPF and require a injected default route.
Router A and B are connected to different internet backbone providers using BGP.
Internally I use iBGP and OSPF. I do not redistribute OSPF routes into BGP, nor do I do the opposite.
Router A injects a default route into the network using OSPF’s default-information originate metric 100.
Router B also injects a default route into the network using OSPF’s default-information originate metric 110.

So, right now all my outbound traffic goes out through router A (because of the metric 100). Inbound traffic comes through both internet connections, based on the preferred BGP route.
Since the IGP (ospf) has the lower IGP metric (in comparison to ibgp) the ospf default routes (0.0.0.0/0) routes determine the flow of outbound traffic. Because of that, I can’t seem to “direct” outbound traffic using a local route map (local-preference). Ideally I would like to be able to direct outbound traffic as specific as I like.

What is the common setup, in terms of BGP and OSPF, on networks that resemble ours?

Thanks
JB




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