From: Mark Lewis (markl11@xxxxxxxxxxx)
Date: Fri Sep 29 2000 - 07:22:06 GMT-3
But, obviously communities are to be used by NEIGHBORING routers, not the
router on which they are set (otherwise setting no-advertise on a route
would cause it never to be advertised out from the router on which this
community was set!!!).
If I implied that what you just said wasn't possible,then I apologise - use
of communities assumes the above.
Mark
>From: Kevin Baumgartner <kbaumgar@cisco.com>
>Reply-To: Kevin Baumgartner <kbaumgar@cisco.com>
>To: markl11@hotmail.com (Mark Lewis)
>CC: ccielab@groupstudy.com
>Subject: Re: BGP community attribute
>Date: Thu, 28 Sep 2000 20:17:16 -0700 (PDT)
>
> >
> > Watch out! You've just given a definition of the 'no-advertise'
>community
> > attribute.
> >
> > No-export - don't advertise to eBGP neighbors. (This route will not go
> > outside the AS).
>
> Well you are wrong. (at least partly)
>
> Just tried the following
>
>
> R1 R2 R3
> AS 1 ----------- AS 2-------- AS 3
>
>
> So start with the following R1 configuration
>
>router bgp 1
> bgp log-neighbor-changes
> network 10.1.1.0 mask 255.255.255.0
> neighbor 192.168.1.2 remote-as 2
>
> So just redistributing 10.1.1.0 network into BGP
>to R2 and R3. Now see the route on R2 and R3.
>
> Now change R1 configuration to do community no-export
>on 10.1.1.0.
>
> router bgp 1
> bgp log-neighbor-changes
> network 10.1.1.0 mask 255.255.255.0
> neighbor 192.168.1.2 remote-as 2
> neighbor 192.168.1.2 send-community
> neighbor 192.168.1.2 route-map no-export out
>access-list 1 permit 10.1.1.0 0.0.0.255
>route-map no-export permit 10
> match ip address 1
> set community no-export
>
> Now after do clear ip bgp * on all routers and once
>BGP is stable only now see the 10.1.1.0 network on R1
>and R2. Don't see on R3.
>
> What defining "community no-export" is to tag this
>route so that it will not be sent out R2.
>
> Kevin
>
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