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If you are not using conderations then they perform the same function as Narbik has listed above. When using confederations, routes set with the local-as community won’t be advertised to confederation eBGP peers while routes marked with no-export will still be advertised to confederation eBGP peers.
- Thor On Tue, Jun 3, 2008 at 5:43 AM, Chuck Ryan (chryan) wrote:
> What was the explanation regarding confederations? That must have been > sent unicast and not to the list. Based on Narbik’s response, local-as > and no-export are the same? That’s how I understood that explanation. > Please correct me if I am mis-understanding that. > > Thanks, > > Chuck > > —–Original Message—– > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of > John Jones > Sent: Monday, June 02, 2008 9:20 PM > To: ccielab@groupstudy.com > Subject: Re: BGP Communities - no-export vs. local-AS > > Thanks Lloyd and Narbik. I kind of figured that it could be associated > with confederations. > > Thanks Narbik for the detailed explanation. It looks like it is a matter > of where the advertisement “boundary” lies. > > John > > > On Mon, Jun 2, 2008 at 8:46 PM, Narbik Kocharians > wrote: > > > Besides the *confederation*, here are some choices: > > > > Let’s say you have R1 in AS 100 and R2 in AS 200. R1 needs to > > advertise network 1.0.0.0/8 to R2, but it does NOT want the routers in > > > AS 200 advertise that route to any of their EBGP peers, R1 can > > accomplish this task in two ways: > > > > 1. R1 can identify the network, in this case 1.0.0.0/8, then configure > > > a route-map and set the community to *no-export* and then send > > community and the route-map to R2. > > 2. R1 can identify the network, in this case 1.0.0.0/8, then configure > > > a route-map and then set the community to *local-as* and then send the > > > community and the route-map to R2. > > > > Now if R2 is advertising network 2.0.0.0/8 and it want that network to > > > stay local (meaning in its own AS) and NOT be advertised to any EBGP > > peer/s, > > R2 can be configured using one of the following: > > > > 1. R2 can be configured to advertise network (2.0.0.0/8) using a > > network statement with a route-map, and the route-map just sets the > > community to * local-as*. > > 2. R2 can be configured to advertise network (2.0.0.0/8) using a > > network statement with a route-map, and the route-map just sets the > > community to * no-export*. > > > > > > On Mon, Jun 2, 2008 at 5:57 PM, John Jones wrote: > > > >> After searching the DocCD, I have been unable to find out the > >> difference between these, other than they are opposite logic. > >> no-export means don’t sent a BGP update out of the AS. local-AS means > > >> keep the update within the AS that the router is in. > >> > >> Is the difference when using confederations? I can see there the > >> significance, but is this the only one? > >> > >> Thanks, guys. > >> > >> John Jones > >> Networking, Linux & Storage Interconnect Trainer Dell Inc. > >> > >> > >> > _______________________________________________________________________ > >> Subscription information may be found at: > >> http://www.groupstudy.com/list/CCIELab.html > >> > >> > >> > >> > >> > > > > > > — > > Narbik Kocharians > > CCSI#30832, CCIE# 12410 (R&S, SP, Security) > > www.Net-Workbooks.com > > Sr. Technical Instructor > > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html > > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html