On Tue, Nov 11, 2003 at 09:55:34AM -0500, Leo Bicknell wrote:
In a message written on Tue, Nov 11, 2003 at 08:35:34AM +0000, Sugar, Sylvia wrote:
I am curious to know if its possible to have a router with its two interfaces, say configured as, 1.1.1.1/16 and 1.1.1.2/16. Theoretically, i see nothing which can stop a router from doing this.
Cisco's don't let you do this. I have always considered that broken, although I'm sure Cisco thinks it's a feature.
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.
Other routers (of note FreeBSD boxes) do this just fine. In almost all cases I've seen it done it was for more bandwidth to the box (typically inbound only, because there are no good tools on Unix boxes to split the traffic between the outgoing interfaces).
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. :) -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)