RE: unusual BGP question. [7:54429]
you're right MED is used for outgoing routing decisions, but... 1.as a optional nontransit path-atribute, it's only important for the neighboring AS. as such, it determines the neighboring AS outgoing decisions, not our own AS ones. e.g if you change MEDs in our routing updates, it causes change only in your neighbors. 2.what the previous posting meant, is modifying the MEDs in the updates, we are getting /at R3? from R1 and R2. As doing that, you can force your outgoing policy, without modifying/as in the original posting terms/ as-path /prepending/ or local-pref change. -rado Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54874t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: unusual BGP question. [7:54429]
I have the impression that MED is only for outbound traffic . For inbound traffic try prepending the routes that you do not wish to use for the priority path . And the routes will automatically follow the path that has no prepend correct me if I am wrong suaveguru --- Jim Brown wrote: What about modify the MED of the route? -Original Message- From: Casey, Paul (6822) [mailto:[EMAIL PROTECTED]] Sent: Saturday, September 28, 2002 9:51 AM To: [EMAIL PROTECTED] Subject: unusual BGP question. [7:54429] Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. Any help appreciated. Kind regards. Paul. This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * [EMAIL PROTECTED] __ Do you Yahoo!? New DSL Internet Access from SBC Yahoo! http://sbc.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54473t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: unusual BGP question. [7:54429]
The original requirement stated you could not modify the AS path or local preference. The MED is the method used to communicate preference to another AS. There is no requirement that the MED can only be set outside of the current AS, you can modify the MED attribute anywhere you like. -Original Message- From: suaveguru [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 29, 2002 1:31 AM To: Jim Brown; [EMAIL PROTECTED] Subject: RE: unusual BGP question. [7:54429] I have the impression that MED is only for outbound traffic . For inbound traffic try prepending the routes that you do not wish to use for the priority path . And the routes will automatically follow the path that has no prepend correct me if I am wrong suaveguru --- Jim Brown wrote: What about modify the MED of the route? -Original Message- From: Casey, Paul (6822) [mailto:[EMAIL PROTECTED]] Sent: Saturday, September 28, 2002 9:51 AM To: [EMAIL PROTECTED] Subject: unusual BGP question. [7:54429] Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. Any help appreciated. Kind regards. Paul. This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * [EMAIL PROTECTED] __ Do you Yahoo!? New DSL Internet Access from SBC Yahoo! http://sbc.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54480t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
unusual BGP question. [7:54429]
Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. Any help appreciated. Kind regards. Paul. This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54429t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: unusual BGP question. [7:54429]
First of all, there are no unusual questions regarding BGP. BGP is all about doing bizarre things in order to meet SLA's or fulfill contractual obligations and customer requirements. One might conclude that there is nothing usual or normal about BGP Focus on how BGP installs a route, and then consider alternatives that would prefer one path over another. Some things that come to mind are AS PATH lengths, weights, communities. There are probably a bunch more that my simple mind can't think of off hand. Read down the list of the ten things BGP considers when installing a route. What commands effect each of those things. HTH Chuck -- www.chuckslongroad.info like my web site? take the survey! Casey, Paul (6822) wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. Any help appreciated. Kind regards. Paul. This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54432t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: unusual BGP question. [7:54429]
Casey, Paul (6822) wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. OK, so you can't set local-pref or prepend the AS string... Things that spring immediately to mind in no particular order are: 1) If both ebgp peerings in AS3 are on the same router, then just set a weight preferencing the AS1 route over the AS2 route. If there are multiple peering routers you could set the weight and a community, and use that community to set a weight on the other BGP routers via a route-map on the iBGP peering. 2) You could set a med, and use the bgp always-compare-med option. 3) You could use a filter/prefix list to refuse accepting that prefix from AS2 in the first place. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. There are a lot of ways to do most things in BGP. local-pref and as-prepend are the most common ways to do this particular type of traffic management, but if you know the decision algorithm and the various prefix-list/distribute-list/filter-list/route-map options that can be applied to a peering there are plenty of other answers to be found. Any help appreciated. Kind regards. Paul. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54438t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: unusual BGP question. [7:54429]
What about modify the MED of the route? -Original Message- From: Casey, Paul (6822) [mailto:[EMAIL PROTECTED]] Sent: Saturday, September 28, 2002 9:51 AM To: [EMAIL PROTECTED] Subject: unusual BGP question. [7:54429] Hello, Anyone any thought on the following lab Im working on, AS 1 and AS2 are connected to AS3 via EBGP as well as each other. (Triangular fashion) AS1 and AS2 both originate and advertise the network 81.0.0.0/8 in to EBGP to AS3 Objective: Ensure that AS3 routes to 81.0.0.0/8 via AS 1. Local preference or AS-path attributes may NOT be modified. I'm thinking to do this, to use policy routing, or is there another way to deal with a situation like this. Any help appreciated. Kind regards. Paul. This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=54468t=54429 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
