Re: BGP aggregate-address with advertise-map

Dear Selamat,

The advertise-map only has to do as per my knowledge with the Autonomous
System Path manipulation let us say you have two sub-routes A/B part being
aggregated as a major subnet X. A has its own as-path and B also has its own
as-path, thus by default the autonomous system path of A & B will be in an
AS-SET format and will both form the AS-Path for the aggregate X.

Check this paragraph taken from Doc-CD:
http://www.cisco.com/en/US/docs/ios/12_3/iproute/command/reference/ip2_a1g.html#wp1037074

"Using the* advertise-map *keyword selects specific routes that will be used
to build different components of the aggregate route, such as AS_SET or
community. This form of the *aggregate-address *command is useful when the
components of an aggregate are in separate autonomous systems and you want
to create an aggregate with AS_SET, and advertise it back to some of the
same autonomous systems. You must remember to omit the specific autonomous
system numbers from the AS_SET to prevent the aggregate from being dropped
by the BGP loop detection mechanism at the receiving router. IP access lists
and autonomous system path access lists *match* clauses are supported. "

Back to your example where you have a summary and 4 routes on R6 and you
want the summary with only two routes to appear on R4

*> 200.0.0.0 54.5.1.254 2297856 32768 ?
*> 200.0.0.0/22 0.0.0.0 32768 i
*> 200.0.1.0 54.5.1.254 2297856 32768 ?
*> 200.0.2.0 54.5.1.254 2297856 32768 ?
*> 200.0.3.0 54.5.1.254 2297856 32768 ?

Well I guess it could be done with two solutions:

1)Keep the aggregate without-summary keyword and use a neighbor suppress-map
and suppress the unneeded subnets (200.0.2.0, 200.0.3.0)

2)Put a summary-only keyword at the end of the aggregate and unsuppress the
two routes the ones you need (200.0.0.0, 200.0.1.0) for this neighbor
(neigbor a.b.c.d unsupress-map)

HTH

On Sun, Sep 5, 2010 at 2:56 PM, selamat pagi <ketimun_at_gmail.com> wrote:

> Can this be achieved with an advertise-map ?
>
>
> On R6 I receive 4 routes via EIGRP and redistribute them into BGP then
> send
> it via EBGP to R4.
> On R4 I need to get a summary-route and the specific-routes for
> 200.0.0.0/24and
> 200.0.1.0/24.
> I cannot change the aggregate-mask.
>
> R6
> router bgp 200
> aggregate-address 200.0.0.0 255.255.252.0 advertise-map ADVERTISE
> redistribute eigrp 10
> neighbor 158.5.46.4 remote-as 100 --> R4
>
> route-map ADVERTISE permit 10
> match ip address prefix-list EIGRP
> !
> route-map ADVERTISE deny 20
> !
> ip prefix-list EIGRP seq 5 permit 200.0.0.0/24
> ip prefix-list EIGRP seq 10 permit 200.0.1.0/24
>
>
> --------------------------------------------------------------------------------
> R6#sh ip bg
> *> 200.0.0.0 54.5.1.254 2297856 32768 ?
> *> 200.0.0.0/22 0.0.0.0 32768 i
> *> 200.0.1.0 54.5.1.254 2297856 32768 ?
> *> 200.0.2.0 54.5.1.254 2297856 32768 ?
> *> 200.0.3.0 54.5.1.254 2297856 32768 ?
>
> R6#sh ip route eigrp
> D 200.0.0.0/24 [90/2297856] via 54.5.1.254, 01:22:00, Serial0/0/0.101
> D 200.0.1.0/24 [90/2297856] via 54.5.1.254, 01:22:00, Serial0/0/0.101
> D 200.0.2.0/24 [90/2297856] via 54.5.1.254, 01:22:00, Serial0/0/0.101
> D 200.0.3.0/24 [90/2297856] via 54.5.1.254, 01:22:00, Serial0/0/0.101
>
> --------------------------------------------------------------------------------
>
> R4#sh ip bgp vpn all
> * i200.0.0.0 158.5.3.3 2297856 100 0 200 ?
> *> 158.5.46.6 2297856 0 200 ?
> * i200.0.0.0/22 158.5.3.3 0 100 0 200 i
> *> 158.5.46.6 0 0 200 i
> * i200.0.1.0 158.5.3.3 2297856 100 0 200 ?
> *> 158.5.46.6 2297856 0 200 ?
> * i200.0.2.0 158.5.3.3 2297856 100 0 200 ? -->
> don't expect route here
> *> 158.5.46.6 2297856 0 200 ?
> * i200.0.3.0 158.5.3.3 2297856 100 0 200 ? -->
> don't expect route here
>
>
> thanks for your help,
> keti
>
>
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-- 
KJ
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