[c-nsp] Dumb question

[Gert Doering]

Hi,

On Wed, Aug 03, 2011 at 06:44:07PM +0300, Ziv Leyes wrote:
>  neighbor RTR1 route-map RTR1-IN in 

What's that for?

>  neighbor ISP1 remote-as 11111
>  neighbor z.z.z.z peer-group ISP1
>  neighbor ISP1 send-community
>  neighbor ISP1 route-map ISP1-OUT out
> (similar settings for ISP2, with opposite prepending settings)
>   
> ip bgp-community new-format
> ip community-list standard COMMUNITY-1 permit 100:1
> ip community-list standard COMMUNITY-2 permit 100:2
> !
> route-map RTR1-IN permit 10
>  match community 100:1
> !
> route-map RTR1-IN permit 20
>  match community 100:2

Whatever it is, it won't work, as you're trying to match on a community
list named "100:1", not "the community 100:1".

It might actually do interesting things, as the prefixes will never
be matched, and fall off the end of the route-map - if there's an implicit
"deny" there [of which I'm never sure with route-maps] RTR2 will just 
reject prefixes from RTR1, and that might be why you don't see the 
*outgoing* announcements towards ISP1 and ISP2.

> !
> route-map ISP1-OUT permit 10
>  match community COMMUNITY-1
> !
> route-map ISP1-OUT permit 20
>  match community COMMUNITY-2
>  set as-path prepend 100 100 100 100
> !

Now this looks very reasonable.

> Now, checking what I see, I get the following:
> 
> RTR1# sh ip bgp neighbor x.x.x.x advertised
>    Network          Next Hop            Metric LocPrf Weight Path
> *> 1.1.1.0/24   0.0.0.0                  0         32768 i
> *> 2.2.2.0/24   0.0.0.0                  0         32768 i
> 
> RTR2# sh ip bgp neighbor y.y.y.y received-routes
>    Network          Next Hop            Metric LocPrf Weight Path
> * i1.1.1.0/24   207.226.45.254           0    100      0 i
> * i2.2.2.0/24   207.226.45.254           0    100      0 i

Looking in "received-routes" won't tell you whether it actually accepted
the route...

> RTR2# sh ip bgp 1.1.1.0
> BGP routing table entry for 1.1.1.0/24, version 7234660
> Paths: (1 available, no best path)
>   Not advertised to any peer
>   Local, (Received from a RR-client), (received-only)
>     y.y.y.y (metric 100) from y.y.y.y (y.y.y.x)
>       Origin IGP, metric 0, localpref 100, valid, internal
>       Community: 100:1

... which it didn't!  It's "received-only", not "active in RTR2's BGP
table".

> BUMMER!!!!
> 
> What I do find very strange is the following:
> route-map RTR1-IN, permit, sequence 10
>   Match clauses:
>     community (community-list filter): 100:1 
>   Set clauses:
>   Policy routing matches: 0 packets, 0 bytes
> route-map RTR1-IN, permit, sequence 20
>   Match clauses:
>     community (community-list filter): 100:2 
>   Set clauses:
>   Policy routing matches: 0 packets, 0 bytes
> 
> See? all the counters are zero!

Sure.  You have no community-list "100:1" and "100:2".

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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