BGP advertise-map with PL

Unanswered Question
Aug 6th, 2009

Hi Experts,


I am configuring BGP "aggregate-address advertise-map" command. Below is the config details for your kind reference


ip prefix-list FILT-PL seq 5 deny 3.1.11.0/24

ip prefix-list FILT-PL seq 10 permit 0.0.0.0/32


access-list 1 deny 3.1.11.0 0.0.0.255

access-list 1 permit any

!

route-map FILT permit 10

match ip address prefix-list FILT-PL


router bgp 200

no synchronization

bgp log-neighbor-changes

network 2.2.0.0 mask 255.255.255.0

network 2.2.1.0 mask 255.255.255.0

network 2.2.2.0 mask 255.255.255.0

network 2.2.3.0 mask 255.255.255.0

aggregate-address 3.1.0.0 255.255.240.0 as-set summary-only advertise-map FILT

neighbor 10.1.12.1 remote-as 100

neighbor 10.1.12.1 send-community

neighbor 10.1.12.1 route-map SAIRAM-NOEXP out

neighbor 10.1.23.3 remote-as 300

no auto-summary


When I use access-list 1, it working fine by not considering attributes of 3.1.11.0 network for aggregation.

Whereas if I use prefix-list FILT-PL it is not working, meaning it is taking the AS number of net 3.1.11.0 also in the aggregation.


I am confused why it is working when using ACL and not PREFIX-LIST


Thanks in advance


sairam

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Peter Paluch Thu, 08/06/2009 - 10:24

Sairam,


I haven't analyzed your configuration in detail right now but I see a problem in your prefix-list.


The second line says:


ip prefix-list FILT-PL seq 10 permit 0.0.0.0/32


Obviously, you wanted to write something similar to "permit any". However, the correct syntax in prefix-lists for this is:


ip prefix-list FILT-PL seq 10 permit 0.0.0.0/0 le 32


In other words, any network (anything AND 0 = 0) with any mask (from /0 to /32).


Try it with this prefix-list and let us know if it worked for you.


Best regards,

Peter


snarayanaraju Thu, 08/06/2009 - 10:41

Hi Peter,


Thanks for correcting the configuration, it is working. Great


sairam

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