Re: On the subject of multihoming

[Scott Doty <scott () sonic net>]

[ resent to list, was sent from the wrong address -sd ]

Charles Wyble wrote:
> I'm working on a small experiment which utilizes multiple outbound 
> links (in the experiments case multiple consumer 3G connections [to 2 
> Sprint/2 Verizon/1 AT&T], Time Warner Cable Modem and an SBC Global 
> DSL connection.
>
> What is the best way to do outbound traffic engineering? I would like 
> to be able to determine the best path possible and send traffic out 
> the appropriate link.

Not sure if this is useful, but I thought I'd contribute a point on the
curve...

from NANOG 9:

  http://www.academ.com/nanog/feb1997/multihoming.html

Obquote: from Paul Vixie's presentation,
from Stan Barber's notes, here is the "meat of the matter":

_ _ _ _ _ _ _
Per-interface Default Route

   * BSD TCP binds outbound route to PCB on SYN-ACK
   * Our trick: remember the inbound interface identity from the SYN
   * Each interface has its own "default route"
   * For outbound TCP and all UDP, a normal default is also needed.

_ _ _ _ _ _ _

Hope that helps...

-Scott