Yes, that's the point. If the "better" upstream is getting congested you need to encourage traffic to take the poor upstream. Avoiding congestion is more important than following a normally optimal AS path. You manipulate the AS path to make a better AS look equally poor".
On Mon, Oct 5, 2009 at 12:00 PM, Paul Hendry <paul.hen...@skyline-networks.com> wrote: > Jon, > > By prepending to/from the "better" upstream peer aren't you > influencing traffic via the "poorer" upstream due to the shorter AS path? > > P. > > -----Original Message----- > From: Jon Auer [mailto:j...@tapodi.net] > Sent: 05 October 2009 18:33 > To: WISPA General List > Subject: Re: [WISPA] Bgp and mt > > 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! 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/ >> >> -- >> This message has been scanned for viruses and >> dangerous content by MailScanner, and is >> believed to be clean. >> >> >> >> >> >> -------------------------------------------------------------------------------- >> 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/ > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > > > > > -------------------------------------------------------------------------------- > 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/
