RE: iBGP next hop and multi-access media

From: Stephen J. Wilcox (no email)
Date: Mon Oct 07 2002 - 15:43:06 EDT

On Mon, 7 Oct 2002, Ralph Doncaster wrote:

[from previous mail]
> > Ralph, how do you intend on getting traffic *OUT* of this subnet?
> > Static arp entries on all the hosts? Proxy arp? It seems like that would
> > be a lot more work and much more failure prone in the long run.
> What, you don't use a static default route on your end hosts? Are you one
> of those crazy types that run RIP on your IIS/NT servers?

Default route yes, to an IP address yes. You have to configure the IP address on
the router tho!

> > Can someone please explain to me *why* are you trying to come up with
> > *complicated* configurations as opposite to
> >
> > (a) defining your connected routes on all the routers that would be using
> > it.
> I've asked because I wanted to know if any routing protocol redistributes
> information about diretly connected multi-access networks.

Yes but only assuming you have a connected IP network or static route, other
routers then have no idea of knowing if they are connected to the same layer 2
media unless you explicity tell them

Regarding the question of statics to multiaccess networks, my personal opinion
on that is that its a bug more than a feature. It shouldnt be allowed as its
messy and by design each station on a multiaccess network should be able to
identify itself and properly map between layers ie IP to MAC via ARP. By static
routing you have no valid source IP...

> It seems pretty obvious to me that if you have a an ethernet segment with
> multiple routers on it that adding a secondary IP to each one is more
> complicated and error-prone than adding it to one and having a dynamic
> routing protocol notify the rest of the routers on the segment.

L2 isnt L3 tho

> It also seems that the answer I was looking for, at least as far as iBGP
> is concerned, is no. However rather than just saying, "no, BGP can't do
> this" many people have decided to brag about how smart they are because
> they don't ask questions about how BGP works.

I think the real question is more of how L3 to L2 protocols function, the fact
that they dont do what is assumed in the original question means the question
about iBGP isnt really valid..

> So now I can sit back and watch the chest-thumping continue...

Oo oo aar aar


> -Ralph

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