BGP Issue - 2 AS on same router ?...

[robad]

Hi Team,

I working in some company's lab that gives services to clients. We are getting the networks/subnets from IT and then distribute it in the lab as we want per client's needs. The gateways for the subnets to get out from the lab to the 'world' is the IT.

Our IT works with BGP and there is something weird that I'm might misunderstand... please let me know if it's reasonable or not.

Here is the description :

Lab A - we have the subnets 10.10.10.0-10.10.50.0 for example

Lab B - we have the subnets 20.20.20.0-20.20.50.0

The IT gave us config to put in our Gateways.

for one lab they told us that the BGP AS should be let's say "11111"

for the 2nd lab the AS should be "22222"

They exposed their config, and in their config we see that for both labs, their AS is the same (let's say "33333"), but one time the

remote-as 

(our side) is : 

neighbor 10.10.10.1 remote-as 11111

and for one is :

neighbor 20.20.20.1 remote-as 22222

They are using the same device for gateway for our 2 labs, and in our side, we also using the same gateway for all labs.

My question is :

How it's possible ? How can I configure it ?

After configuring the "11111" AS at my GW, if I'll try now to configure AS "22222", it won't let me, because there is already an AS.....

Or that the IT should give me other configs, or that I'm missing something very basic in BGP understanding. (It's the 1st time we are using BGP with the IT)

Can someone please assist with that ? we are truing to understand it for 2.5 weeks without success.

Thanks a lot in advance for any piece of info !

[vencislav.metev]

Hi,

You can run only one BGP process with local AS number.

If you want to make a session and change your own AS number you can use

neighbor x.x.x.x local-as AS-Number

command.

Regards,

Ventsi

[balaji.bandi]

Look at some example :

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html

[paul driver · Accepted solution]

Hello

ASN - 33333 rtr

router bgp 33333
neighbor 10.10.10.x remote-as 11111
neighbor 20.20.20.x remote-as 22222



ASN -11111 rtr

router bgp 11111
neighbor 3.3.3..x remote-as 33333


ASN- 22222 rtr

router bgp 22222
neighbor 3.3.3..x remote-as 33333