ASR1006 BGP with 4 byte public ASN and 2 byte private ASN

[md_s_mannan]

Is it possible to implement BGP for 2 ASN numbers on the same ASR1006.  Here one is 4 byte public ASN and the other is 2 byte private ASN.

Let me try to make your understand my scenario first:

I've a public IPv4 block say (a.a.a.a/24), that has to advertised through the 4 byte public ASN number on a ASR1006. Through the same router I've to advertise the same public IP block (a.a.a.a/24) to a private network with private IPv4 peering IP block and private ASN. where the private network organizer team have provided me a 2 byte private ASN as well. In such case what would be the best procedure to import the routes from both the networks.

Your valuable advice and configuration steps would help me alot.

Thanks in advance.

//

Mannan

[vivek srivastava]

You need to use "local-as" feature of BGP. Refer my below post with similar requirements.

https://supportforums.cisco.com/discussion/12501791/can-you-have-multiple-bgp-s-running-simultaneously-3560

Cisco documentation:

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-39.html

[md_s_mannan]

Thanks very much, Mr. Vivek. It is really helpful. I am working on it. Hopefully by day after tomorrow I'll be able to make a test case and prepare a script. I will again come back soon to paste my script including the test case, so that it can be checked by you.

I hope you would not mind to check the script for me.

Again Thanks Very Much.

//

Mannan

[md_s_mannan]

Hi vivek.

I was working on the following case.

Case:

# I'm working in a router that has a 4 byte public ASN, 2 byte private ASN, and 2 public /24 IP blocks those has to be advertised.

Script for the Case:

Step 01: Build prefix list to be advertised and imported

========================================================

ip prefix-list IP1-EXPORT-TO-ISP seq 5 permit Y.Y.Y.Y/24 (PUBLIC IP)

ip prefix-list IP2-EXPORT-TO-ISP seq 5 permit Z.Z.Z.Z/24 (pUBLIC ip)

ip prefix-list IMPORT-FROM-ISP seq 5 permit 0.0.0.0/0

Step 02: Build Route Map based on which, IP and AS blocks will be filtered to be export/import

==============================================================================================

route-map PATH_PREPEND permit 10

set as-path prepend AAAAAA AAAAAA AAAAAA (PUBLIC ASN)

route-map PATH_PREPEND_LOCAL permit 10

set as-path prepend BBBBB BBBBB BBBBB (PRIVATE ASN)

route-map IP_IMPORT permit 10

match ip address prefix-list IMPORT-FROM-ISP

set local-preference 200

route-map IP1_EXPORT permit 10

match ip address prefix-list IP1-EXPORT-TO-ISP

set origin igp

route-map IP2_EXPORT permit 10

match ip address prefix-list IP2-EXPORT-TO-ISP

set origin igp

Step 03: BGP CONFIGURATION

==========================

router bgp AAAAAA

aggregate-address Y.Y.Y.Y 255.255.255.0

aggregate-address Z.Z.Z.Z 255.255.255.0

neighbor Q.Q.Q.1 remote-as CCCCC (BGP: PUBLIC)

neighbor Q.Q.Q.1 description 2Public

neighbor Q.Q.Q.1 ebgp-multihop 5

neighbor Q.Q.Q.1 version 4

neighbor Q.Q.Q.1 timers 10 30

neighbor Q.Q.Q.1 soft-reconfiguration inbound

neighbor Q.Q.Q.1 route-map IP1-EXPORT out

neighbor Q.Q.Q.1 route-map IP2-EXPORT out

neighbor Q.Q.Q.1 route-map IP_IMPORT in

neighbor Q.Q.Q.1 route-map PATH_PREPEND out

neighbor R.R.R.1 remote-as DDDDD (BGP: PRIVATE)

neighbor R.R.R.1 local-as BBBBB

neighbor R.R.R.1 description 2Private

neighbor R.R.R.1 ebgp-multihop 5

neighbor R.R.R.1 version 4

neighbor R.R.R.1 timers 10 30

neighbor R.R.R.1 soft-reconfiguration inbound

neighbor R.R.R.1 route-map IP1-EXPORT out

neighbor R.R.R.1 route-map IP2-EXPORT out

neighbor R.R.R.1 route-map IP_IMPORT in

neighbor R.R.R.1 route-map PATH_PREPEND_LOCAL out

My question is, if the configuration is OK/sufficient. or need to add/modify things here.

Thanks in advance.

//

Mannan

[rosaho]

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