permit specify community to prefix list

[admin@atrinnet.net]

Hi Dears

I have Prefix list filter for uplink 1 and uplink 2

Filter out by prefix-list

No my qustion id How used community string in prefix list according the picture if customer

annouce prefix by community 100:1 announce on uplink 1

if announce by comminuty 100:2 announce to uplink 2

Pleas help me ?

[Harold Ritter]

Hi admin@atrinnet.net ,

You can do that using a route-map. You will need to replace the current prefix-list filters with a route-map, as follow:

router bgp 100

neighbor <uplink1 address> route-map uplink1 out

neighbor <uplink2 address> route-map uplink2 out

!

route-map uplink1 permit 10
match ip address prefix-list <prefix-list name you currently use>
match community 1
route-map uplink1 deny 20
match ip address prefix-list <prefix-list name you currently use>
match community 2
route-map uplink1 permit 30
match ip address prefix-list <prefix-list name you currently use>

!

route-map uplink2 permit 10
match ip address prefix-list <prefix-list name you currently use>
match community 2
route-map uplink2 deny 20
match ip address prefix-list <prefix-list name you currently use>
match community 1
route-map uplink2 permit 30
match ip address prefix-list <prefix-list name you currently use>

!

ip community-list 1 permit 100:1
ip community-list 2 permit 100:2

If the prefix match both the prefix-list and community 100:1, it will be sent only to uplink1

If the prefix match both the prefix-list and community 100:2, it will be sent only to uplink2

If the prefix only match the prefix-list, it will be sent to both uplink1 and uplink2.

Regards,

[MHM Cisco World]

Also he need 

1- ip bgp new format <- global mode

2- neighbor x.x.x.x send-community both <- under bgp of neighbor inject community 

MHM

[Harold Ritter]

Hi @MHM Cisco World ,

> 1- ip bgp new format <- global mode

The configuration I recommended will work without this command. I agree though that it makes it easier to read the community value (100:1 instead of 6553601).

> 2- neighbor x.x.x.x send-community both <- under bgp of neighbor inject community 

Obviously, this technique will not work if the customer doesn't send the required communities.

Regards,

[admin@atrinnet.net]

Send commumity define of left side IBGP neighbors

[admin@atrinnet.net]

Only on route-map match ip prefix-list and match community

no action define ????

[Harold Ritter · Accepted solution]

Hi admin@atrinnet.net ,

Both route-maps have a match for prefix-list and community-list. The action is permit or deny. You can add set statement if you want to.

Regards,