nanog mailing list archives

Re: iBGP next hop and multi-access media


From: Jared Mauch <jared () puck Nether net>
Date: Mon, 7 Oct 2002 00:59:24 -0400


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 () 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 () puck nether net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.


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