nanog mailing list archives

Re: iBGP next hop and multi-access media


From: Ralph Doncaster <ralph () istop com>
Date: Mon, 7 Oct 2002 00:42:32 -0400 (EDT)


My understanding is the route is valid as long as the interface is
up; just like adding a secondary IP on the interface.

Ralph Doncaster
principal, IStop.com 

On Mon, 7 Oct 2002, Alex Rubenstein wrote:


Aha.

So, if you route to a ethernet interface, it will try to arp for that
address on that subnet, even without having a local address on the same
subnet?

This seems to me to be something you don't want to do.

Is the entire route valid as long as the router can ARP for one of the
addresses in the routed subnet?



On Mon, 7 Oct 2002, Ralph Doncaster wrote:

On Mon, 7 Oct 2002, Alex Rubenstein wrote:

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) ?

When you setup a secondary ip on an interface
 int fa0/0
   ip address a.b.c.d e.f.g.h secondary

How does it determine where to send the packets?  ARP.
Which is the same as adding the route described above.

-Ralph


-- Alex Rubenstein, AR97, K2AHR, alex () nac net, latency, Al Reuben --
--    Net Access Corporation, 800-NET-ME-36, http://www.nac.net   --





Current thread: