Ok, so correct me if I'm wrong here (I'm just trying to paint a picture of what this thread is trying to conceive), RA-FA1: 10.10.10.1/30, RB-FA0: 10.10.10.2/30, 172.16.16.1/24 secondary? iBGP setup between RA & RB, RB announces to RA with a next-hop of the primary address on FA0, RA announces to RB with a next-hop of the primary address on FA1. When iBGP announces 172.16.16 to RA, you want it announce with a next-hop of 172.16.16.1 as opposed to the primary address 10.10.10.2. Is that right?
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Ralph Doncaster Sent: Monday, October 07, 2002 12:56 AM To: Jason Lixfeld Cc: 'Alex Rubenstein'; nanog@merit.edu Subject: RE: iBGP next hop and multi-access media
It's a theoretical question. So far I've had one person email me saying OSPF can advertise a subnet as local on a shared multi-access media. If in fact BGP can't do this, then it's no big deal to me as nothing in my network relies on this functionality.
Ralph Doncaster principal, IStop.com
On Mon, 7 Oct 2002, Jason Lixfeld wrote:
Are you just asking a question to get a better understanding of how things work, Ralph or have you already put this into production and are wondering why it doesn't work a certain way?
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Ralph Doncaster Sent: Monday, October 07, 2002 12:43 AM To: Alex Rubenstein Cc: nanog@merit.edu Subject: Re: iBGP next hop and multi-access media
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 --