[c-nsp] IGP & iBGP Configuration Problem in Transit AS

[Vira W]

Guys, thanks a lot for all your kind suggestion. I'll try tunneling
method first, then if I have a little spare time, I'll implement MPLS.

Thanks a lot :)

On 6/16/08, Nathan <have.an.email at gmail.com> wrote:
> On Mon, Jun 16, 2008 at 11:20 AM, Vira W <muarwi at gmail.com> wrote:
>>
>>  My first problem is in IGP configuration inside AS 100. I'm using OSPF. I
>> still confused how to make non-BGP router (C,E,B,D) understand how route
>> the
>> packet transitting this AS.
>
> You can't. Options:
>
> a) make C E B D speak BGP with all applicable routes
>
> b) change your network topology so that it still works if you remove
> all non-BGP-speaking routers (just a connection from A to any of G, F,
> or H should do it, but you won't have a lot of redundancy), and make
> very sure your IGP doesn't route packets for BGP routers through
> non-BGP routers
>
> c) set up tunnels (watch out for MTU problems)
>
> d) implement Layer-2 connections across your backbone using switches
> and VLANs and such
>
> e) implement MPLS
>
> Personally I'd go for MPLS, but YMMV.
>
>> Second, I understand that iBGP inside AS 100 needs to be configured in
>> mesh
>> topology. Otherwise, use route reflector or confederation. But, if I use
>> route reflector, I'm confused because the each route reflector itself must
>> be meshed, in the other side, from the physical topology (as in the
>> picture), there is none router that is connected mesh. So, which router
>> should I choose as RR. Then, if I choose BGP confederation, still inside
>> sub-AS the router must be connected in mesh topology, which impossible
>> from
>> the topology.
>
> The mesh is logical (having to do with iBGP neighbor configuration on
> the routers) not physical (having to do with physical network
> connections between routers). In this context a mesh means that every
> router must be configured as an iBGP neighbor to all the others (plus
> restrictions in option b) above).
>
> --
> HTH
> Nathan
>