Prepending on *inbound* BGP will influence local route selection/*outbound* traffic.
You can use MED in influence inbound traffic from the same AS http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094934.shtml You need localpref to distribute outbound preference throughout a iBGP network when you have multiple egress points across multiple border routers. http://www.cisco.com/en/US/docs/internetworking/technology/handbook/bgp.html#wp1020583 Both are unnecessary when you have one border router talking to two different upstream AS and no downstream AS. In my situation we have 2 fixed bandwidth upstreams and a link to a peering exchange. Upstream A has very good peering so we prepend 3 times from them and 1 time to them. Upstream B has poor peering so we do not prepend anything from them and 1 time to them. This happens to cause a fairly even *outbound* traffic flow. We do not prepend anything to or from peers. We prepend 1 out on all our paid transit links as a tie-breaker for traffic from downstreams of our peers. No need for MED or localpref. If you need to adjust inbound or outbound flows you change the number of prepends. You mileage may vary. Prepending alone resolved my traffic engineering needs without causing any bad side effects. On Mon, Oct 5, 2009 at 11:20 AM, Paul Hendry <paul.hen...@skyline-networks.com> wrote: > AS prepend tends to be only for inbound traffic, to influence outbound you > can use a few different BGP attributes. There is a pecking order (at least in > Cisco) as per below: > > Weight > Local preference > Multi-exit discriminator > Origin > AS_path > Next hop > Community > > Cheers, > > P. > > -----Original Message----- > From: Jon Auer [mailto:j...@tapodi.net] > Sent: 05 October 2009 17:18 > To: WISPA General List > Subject: Re: [WISPA] Bgp and mt > > The most common method is to prepend your AS number to the path that > you announce to the ISP that you want to de-prioritize. > You would use set-bgp-prepend on the inbound route filter for the > connection that you want to de-prioritize. I'd prepend 1, wait a > couple of days and then prepend 2 if necessary. > > On Mon, Oct 5, 2009 at 11:09 AM, Sales <sa...@michianawireless.com> wrote: >> Awesome but that wasn't much help lol. >> >> John Buwa >> Michiana Wireless,Inc >> 574-233-7170 >> Sent from my iPhone >> >> On Oct 5, 2009, at 12:02 PM, "Dennis Burgess" >> <dmburg...@linktechs.net> wrote: >> >>> Plenty of ways :) >>> >>> ----------------------------------------------------------- >>> Dennis Burgess, CCNA, A+, Mikrotik Certified Trainer >>> WISPA Board Member - wispa.org >>> Link Technologies, Inc -- Mikrotik & WISP Support Services >>> WISPA Vendor Member >>> Office: 314-735-0270 Website: http://www.linktechs.net >>> LIVE On-Line Mikrotik Training >>> Author of "Learn RouterOS" >>> >>> >>> -----Original Message----- >>> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] >>> On >>> Behalf Of Sales >>> Sent: Monday, October 05, 2009 11:01 AM >>> To: WISPA General List >>> Subject: [WISPA] Bgp and mt >>> >>> We have two bgp sessions with different providers using the same >>> interface. One provider is metered the other is flat rate. However we >>> seem to send 80% of traffic to the metered provider. Is there a way to >>> tell a mt router using bgp which path you prefer it to use ? I would >>> like to make our flat rate primary choice with the metered secondary. >>> >>> Thanks >>> John >>> >>> >>> --- >>> --------------------------------------------------------------------- >>> -------- >>> WISPA Wants You! Join today! >>> http://signup.wispa.org/ >>> --- >>> --------------------------------------------------------------------- >>> -------- >>> >>> WISPA Wireless List: wireless@wispa.org >>> >>> Subscribe/Unsubscribe: >>> http://lists.wispa.org/mailman/listinfo/wireless >>> >>> Archives: http://lists.wispa.org/pipermail/wireless/ >>> >>> >>> --- >>> --- >>> --- >>> --- >>> -------------------------------------------------------------------- >>> WISPA Wants You! Join today! >>> http://signup.wispa.org/ >>> --- >>> --- >>> --- >>> --- >>> -------------------------------------------------------------------- >>> >>> WISPA Wireless List: wireless@wispa.org >>> >>> Subscribe/Unsubscribe: >>> http://lists.wispa.org/mailman/listinfo/wireless >>> >>> Archives: http://lists.wispa.org/pipermail/wireless/ >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: wireless@wispa.org >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> > > > -------------------------------------------------------------------------------- > WISPA Wants You! 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