Useful if you're using private AS addressing (AS 64512-65535) and you want your customer routes to appear as if they originated from your AS...
I would have used a NO_EXPORT community on the routes being advertised from the AS and simply just advertised the address space that I own. It's rarely useful to advertise your own address space with a differing AS number. It's also more advised to keep advertising the correct AS in cases where this situation would occur, e.g., a dual-homed customer. However, to satisfy the question you can use BGP aggregation on R3 which was specifically designed for this purpose... router bgp 64512 aggregate-address 200.200.200.1 255.255.255.0 summary-only as-set You should only use a set-community conferderation route map when you have complex business rules that you need implemented. WAYNE BAETY, MCSE, A1C, USAF Network Systems Trainer -----Original Message----- From: news [mailto:[EMAIL PROTECTED]] Sent: Monday, November 05, 2001 2:53 AM To: [EMAIL PROTECTED] Subject: Re: BGP question [7:25130] Hi what I am trying to achieve is as follow AS 100 is connected to AS 200. AS 200 is connected to AS 300 AS 100 has route from AS 300. So the AS-PATH List is: 200, 300, i The task is: AS 100 should see all the route from AS 300 as if they came from AS 100 directly the path will look like 200, i Faisal ""Chuck Larrieu"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > interesting question. a seach among the command references and > configuration guides on CCO yields nothing under 12.1, but under 12.2 states > this command was introduced in 12.0(4.4)S and that in 12.0(5)T > the address family configuration mode was added. > > I copied this stuff out of CCO, but it is not making sense to me at the > moment. I can find no reference to the command and function in Parkhurst, > which carries a 2001 copyright but no telling when the contents were locked > down for publishing. > > In re-reading this thread and the documentation below, I'm still a bit > unclear as to what is being accomplished here. Telling a neighbor you are AS > X when you are really AS Y ?? > > I'm working on some BGP scenarios now, so I'll try to add this to the list > and report back. > > Chuck > > ---------- > stuff from CCO: > > > The next example shows how the route map named set-community is applied to > the outbound updates to neighbor 171.69.232.50 and the local-as community > attribute is used to filter the routes. The routes that pass access list 1 > have the special community attribute value local-as. The remaining routes > are advertised normally. This special community value automatically prevents > the advertisement of those routes by the BGP speakers outside autonomous > system 200. > > router bgp 65000 > network 1.0.0.0 route-map set-community > bgp confederation identifier 200 > bgp confederation peers 65001 > neighbor 171.69.232.50 remote-as 100 > neighbor 171.69.233.2 remote-as 65001 > ! > route-map set-community permit 10 > set community local-as > > > neighbor local-as > To allow customization of the autonomous system number for external Border > Gateway Protocol (eBGP) peer groupings, use the neighbor local-as command in > address family or router configuration mode. To disable this function, use > the no form of this command. > > Command History Release Modification > 12.0(4.4)S > This command was introduced. > > 12.0(5)T > Address family configuration mode was added. > > > > > Usage Guidelines > > Each BGP peer or peer group can be made to have a local autonomous system > value for the purpose of peering. In the case of peer groups, the local > autonomous system value is valid for all peers in the peer group. > > This feature cannot be customized for individual peers in a peer group. > > If this command is configured, you cannot use the local BGP autonomous > system number or the autonomous system number of the remote peer. > > This command is valid only if the peer is a true eBGP peer. This feature > does not work for two peers in different subautonomous systems in a > confederation. > > Examples > > The following address family configuration example shows the customization > of neighbor 172.20.1.1 configured to have an autonomous system number of 300 > for the purpose of peering: > > router bgp 109 > address-family ipv4 multicast > network 172.20.0.0 > neighbor 172.20.1.1 local-as 300 > > The following router configuration example shows the customization of > neighbor 172.20.1.1 configured to have autonomous system number of 300 for > the purpose of peering: > > router bgp 109 > network 172.20.0.0 > neighbor 172.20.1.1 local-as 300 > > > end of stuff from CCO > ----------------- > > > ""adam lee"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > What version of IOS is that command in? I am using 12.0(9) and it's not in > > there. > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > > news > > Sent: Saturday, November 03, 2001 12:23 PM > > To: [EMAIL PROTECTED] > > Subject: Re: BGP question [7:25130] > > > > > > I think I got the correct answer > > > > On R3, use neighbor ip address local-as AS# > > > > Faisal > > > > ""Wojtek Zlobicki"" wrote in message > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > Oops, > > > > > > I misunderstood the question... what is the correct answer ? > > > > > > > How is this command going to change the AS path list. The require > task > > > was > > > > that R4 should see the loopback is from AS 200 not AS 100 (which is > the > > > > originator). > > > > > > > > Faisal > > > > > > > > > > > > ""Wojtek Zlobicki"" wrote in message > > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > > ""news"" wrote in message > > > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > > > Hello, > > > > > > > > > > > > greetings... > > > > > > While practicing for CCIE lab, I encounter a question that is > > > something > > > > > like > > > > > > this > > > > > > > > > > > > Topology: > > > > > > R1 ---- R3 ----- R4 > > > > > > > > > > > > R1 is on AS 100 > > > > > > R3 is on AS 200 > > > > > > R4 is on AS 500 > > > > > > > > > > > > There is a loopback address on R1 Loopback0 200.200.200.1/24. I > am > > > > > suppose > > > > > > to advertise this through BGP. Now, in normal case, R4 should see > > > this > > > > > > network coming from AS 200 and then AS 500 > > > > > > > > > > > > My task is to configure R3 with one statement so that R4 see this > > > > loopback > > > > > > coming from AS 200 instead of AS 500? > > > > > > Any idea how this is done? > > > > > > > > > > neighbor R3_LOOPBACK next-hop-self > > > > > > > > > > > > > > > > > > > > > > Thanks in advance. I appreciate your help. > > > > > > > > > > > > Faisal Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=25239&t=25130 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
