iBGP next hop and multi-access media

Jared Mauch jared at puck.Nether.net
Mon Oct 7 04:59:24 UTC 2002


On Mon, Oct 07, 2002 at 12:15:40AM -0400, Alex Rubenstein wrote:
> 
> 
> OK, I'll bite.
> 
> I've been doing ip route statements going on 8 years now, and I can't
> imagine why ever -- and how it would even work -- you'd want to ip route a
> netblock with a next hop of a multi-access brandcast media. As in, the
> next hop is still truly undetermined.
> 
> I guess I don't know this because I've never tried it. But, how does the
> router determine where to send the packets for a route statement as
> specified above (ip route a.b.c.d e.f.g.h f0/0) ?

	A cisco router with the default (ip proxy-arp) enabled on
the interface will spend all its time doing arp/proxy-arp for the hosts and
it will actually work believe it or not.

	You'll notice massive cpu utilization.

	People who do this tend to not have a lot of clue or notice
when their cpu is spending all its time doing this...  One should
always turn proxy-arp off on your interfaces both internal and customer
facing so they don't make your router bear the load because they can
not configure their devices logically.

	- Jared

> > So then what do you call a connected route (for an ethernet interface on a
> > router)?  If you use ethernet, at the edges of your network you HAVE to
> > route IP blocks to the ethernet.
> >
> > -Ralph
> >
> 
> -- Alex Rubenstein, AR97, K2AHR, alex at nac.net, latency, Al Reuben --
> --    Net Access Corporation, 800-NET-ME-36, http://www.nac.net   --
> 

-- 
Jared Mauch  | pgp key available via finger from jared at puck.nether.net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.



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