On 29/03/06, Claudio Jeker <[EMAIL PROTECTED]> wrote:
>
> On Wed, Mar 29, 2006 at 01:33:15PM +0100, tony sarendal wrote:
> > > > The second problem is, that I want to announce an external
> full-feed,
> > > > received with openbgpd, to my core-router. This works fine, but the
> > > > next-hop is the ip-adress of my external bgp-neighbor. But it should
> > > > be the ip-address of the border-router.
> > >
> > > of course! you should have an IBGP that makes your other routes have a
> > > route to that... like OpenOSPFD :)
> >
> >
> > or rewrite nexthop so you can run without an IGP.
> >
>
> ... and call for a lot of trouble when your network is growing.
> IMO this is a bad advice. 90% of all "set nexthop" usages are a hack
> around a network design error. No matter if it is on OpenBSD, cisco or
> whatever.
I don't agree.
A large network does not have to have an IGP to carry the BGP,
no matter size, it depends of the requirements of the network.
A normal design is to use the IGP for to carry the network (links and
loopbacks)
and punch the rest into BGP. A BGP-only design will allow you to have
features
like per-link-direction routing for every single prefix which wil allow you
to do
traffic engineering in a network per prefix by just modifying origination
point
bgp communities. I.e I want this specific prefix to have it's metric bumped
by 100
on the LON->AMS and 500 on OSL->STO to offload this traffic of away
from those links
for a while. Or I don't want this prefix advertised over links which has MTU
less that 4470
to avoid fragmentation.
You can do a lot of things in a bgp-only network which you can't do with an
IGP,
as long as the limitations that bgp offers aren't a show stopper for you,
and as long
as it suites the network you are running.
Also I have seen countless network problems just due to problems in one of
the many
routing and forwarding layers, think protocol pancakes and mpls, one
protocol is simple.
/Tony
--
Tony Sarendal - [EMAIL PROTECTED]
IP/Unix
-= The scorpion replied,
"I couldn't help it, it's my nature" =-
