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Community Member

BGP advertise issue

Hi,

we established private bgp with a customer, and they advertise several routes to us from two sites.

10.1.1.0/24

10.1.2.0/24

10.2.1.0/24

and only one of the route 10.1.1.0/24 set with tag, is that possible I could force all traffic (including 10.1.1.0/24, 10.1.2.0/24 and 10.2.1.0/24) sent back to where their bgp set tag?

thx

11 REPLIES

Re: BGP advertise issue

i dont whether i understood your question properly..

If you want to set the tag for all the incoming routes you can use a route-map for the routes received from the BGP peer

access-list 1 permit 10.1.1.0 0.0.0.255

access-list 1 permit 10.1.2.0 0.0.0.255

access-list 1 permit 10.2.1.0 0.0.0.255

route-map SetTag permit 10

match ip address 1

set tag

router bgp 100

neighbor 1.1.1.1 remote-as 200

neighbor 1.1.1.1 route-map SetTag in

HTH, rate if it does

Narayan

Community Member

Re: BGP advertise issue

Hi, Narayan:

Thanks for your quick reply, the problem is we have two sites, and we have a bgp peer with customer at each site. and they could set the tag dynamically just for 10.1.1.10/24 from site a or site b. and I need to force the traffic back where the site tag has been set.

thx

Cisco Employee

Re: BGP advertise issue

Narayan,

You can't use tags with BGP. In most IOS releases, you would get the following message if you try to configure a route-map that sets the tag for a BGP session:

RouterA(config-router)#nei 192.168.12.2 route-map test in

% "test" used as BGP inbound route-map, set tag not supported

RouterA(config-router)#nei 192.168.12.2 route-map test out

% "test" used as BGP outbound route-map, set tag not supported

RouterA(config-router)#do sh route-ma test

route-map test, permit, sequence 10

Match clauses:

Set clauses:

tag 999

Policy routing matches: 0 packets, 0 bytes

You would rather use the community attribute instead.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Community Member

Re: BGP advertise issue

sorry, my mistake, I meant 10.1.1.0/24 has been set with community, but I want all the traffic sent back to them where the peer which set the community.

thx

Cisco Employee

Re: BGP advertise issue

From what I understand of your setup, you could just set a higher local preference when based on the received community.

Also, to ensure attached community attributes are sent peer, make sure the peer is configured with the "neighbor send-community" command.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Community Member

Re: BGP advertise issue

Hi, Hritter:

that only resolve 10.1.1.0/24 issue, but it does not resolve 10.2.1.0/24 issue, which they did not attatch any community.

Cisco Employee

Re: BGP advertise issue

OK, you have to tell us a bit more about the problem you are trying to solve.

Do you receive all three mentioned prefixes from both peers?

Do you run iBGP between your two routers?

Do you redistributed in the IGP?

Thanks,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Community Member

Re: BGP advertise issue

Do you receive all three mentioned prefixes from both peers?

yes

Do you run iBGP between your two routers?

yes

Do you redistributed in the IGP?

no

thx

Cisco Employee

Re: BGP advertise issue

Could you please then explain what you are trying to achieve.

Thanks,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
Community Member

Re: BGP advertise issue

Hi, Hritter:

we established private bgp with a customer, and they advertise several routes to us from two sites.

10.1.1.0/24

10.1.2.0/24

10.2.1.0/24

customer from site A sends 10.1.1.0/24 with community 65501:10, but no community with route 10.1.2.0/24 and 10.2.1.0/24

also they have site B send all those routes as well with no community attached.

but customer could send 10.1.1.0/24 with community from site A or site B dymanically.

No from Both sites.

our site C is connected with customer site A

site D is connected with customer site B

when I see 10.1.1.0/24 with community attached, I want to force the traffic back on all customer routes where they sent.

thx

Cisco Employee

Re: BGP advertise issue

The best thing would be to ask your customer to set the community attribute for all prefixes on the site where they want traffic to come back.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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