nanog mailing list archives
Re: Router with 2 (or more) interfaces in same network
From: Leo Bicknell <bicknell () ufp org>
Date: Tue, 11 Nov 2003 11:03:46 -0500
In a message written on Tue, Nov 11, 2003 at 10:34:31AM -0500, Richard A Steenbergen wrote:
I'm not sure how Cisco is wrong on this one. If you want 2 router interfaces to have the same route and you actually want both of them to work, it means at the very least you must have a non point-to-point medium, such as Ethernet. In this case, the correct configuration would be a bridge-group and IRB, creating a virtual routed interface with 2 physical ports for bridging.
Correct config yes, however it doesn't have some of the load balancing properties the other "hack" method does. Given how many other ways Cisco will let you shoot yourself in the foot, this particular "feature" seems odd. I've asked about it before though, and it seems to a under-the-hood issue due to the way they do arp.
I love FreeBSD, but it's routing code is probably the thing you least want to look to for examples on how things should be. BTW there is a netgraph module for L2 hash-based load balancing (aka etherchannel without the PAgP/LACP), but yeah the lack of ECMP and a reasonable switching method to support it falls into the category of the previous sentence. :)
Well, s/FreeBSD/{Linux,SunOS,HP-UX,OSF/1,probably others}/. I've seen this done a lot with various unix boxes. Never tried on a Juniper. My point was simply that there are boxes that will let you do this, and that some people do it with great success to solve specific problems. Doesn't mean it's not a hack, or that an ISP should "support" that type of configuration. -- Leo Bicknell - bicknell () ufp org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/ Read TMBG List - tmbg-list-request () tmbg org, www.tmbg.org
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Current thread:
- Router with 2 (or more) interfaces in same network Sugar, Sylvia (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Richard Cox (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Leo Bicknell (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Richard A Steenbergen (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Leo Bicknell (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Crist Clark (Nov 11)
- Re: Router with 2 (or more) interfaces in same network sthaug (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Leo Bicknell (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Neil J. McRae (Nov 12)
- Re: Router with 2 (or more) interfaces in same network Stephen J. Wilcox (Nov 12)
- Re: Router with 2 (or more) interfaces in same network Richard A Steenbergen (Nov 11)
- <Possible follow-ups>
- RE: Router with 2 (or more) interfaces in same network Shawn Solomon (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Paul S. Brown (Nov 11)
- RE: Router with 2 (or more) interfaces in same network Lucas Iglesias (Nov 11)
- Re: Router with 2 (or more) interfaces in same network Frank Louwers (Nov 11)
- RE: Router with 2 (or more) interfaces in same network Peter John Hill (Nov 11)