BGP / OSPF - multihomed to 2 ISPs via multiple local routers

[nextgen.systems]

I was wondering if anyone could point me into the right direction in setting up a multihomed environment to 2 ISPs via multiple local routers using OSPF / BGP ???

Any config examples would be much appreciated.

This is the scnario:

ISP A ISP B

^ ^

^ ^

Router1 ---- Router2

| \ / |

| \ / |

| / \ |

| / \ |

Router3 --- Router4

Router1 eBGP with provider A

Router1 iBGP with Router2

*also runs OSPF

Router2 eBGP with provider B

Router2 iBGP with Router1

*also runs OSPF

Routers 3 & 4 run OSPF

[rgrcommo]

http://www.cisco.com/warp/customer/459/40.html#4

Should help you out there.

Jeff

[trajeem]

I am unable to open the site.It is asking for a CCO login.

[ruwhite]

Try:

http://www.cisco.com/warp/public/459/40.html#4

:-)

Russ.W

[nextgen.systems]

Thanks for you reply Jeff, ... I have seen this doco, I have the BGP setup pretty much under my belt my the OSPF routing is what I am the most interested at this moment, in particular to do with edge routing, boarder routing.

Cheers,

[ruwhite]

What part of the ospf configuration are you interested in? It should just be straight making certain both routers are running ospf, and they can see the next hops that BGP needs correctly.

Unless you're thinking about the synchronization stuff (which has been marked as historical by the IETF, and the defaults should flip on Cisco at some point, I would think, to no sync) (?).

:-)

Russ.W

[nextgen.systems]

Well, I am new to OSPF ... so any cofig examples that fall within my requirements will help.

The diagram that I published before didn't come up the way I want it, ...so here it comes the 'written' vesion:

The 4 routers live in a fully meshed environment

Router 1 has 3 int, 1 to ISPA, 1 on network 1.1.1.0, the other on network 1.1.2.0

Router 2 has 3 int, 1 to ISPB, 1 on network 1.1.1.0, the other on network 1.1.2.0

Router 3 has 3 int, 1 on network 2.2.1.0(internal nw), 1 on network 1.1.1.0, the otehr on network 1.1.2.0

Router 4 has 3 int, 1 on network 2.2.2.0(internal nw), 1 on network 1.1.1.0, the otehr on network 1.1.2.0

Any help would be much appreciated.

[rgrcommo]

Hi-

You may have seen this link already but it will tell you how to best solve your OSPF config/design with what you want to do. If your new to OSPF this would be a good place to start.

http://www.cisco.com/en/US/tech/tk365/tk480/technologies_design_guide09186a0080094e9e.shtml

or

http://www.cisco.com/en/US/tech/tk365/tk480/technologies_q_and_a_item09186a0080094704.shtml