Can I use my ASN number on two separate networks?

[ciscofreak1241]

I have a question in regards to using your ARIN registered ASN for other networks.

I have a data center in San Jose with three /24 subnets. Our ASN is 1234 (example). We are advertising our three subnets via BGP using our ASN.

Well I have a new data center in New York that will have a /24 subnet and we want to advertise this subnet via BGP using our same ASN 1234 number. It will have no direct connection to the San Jose data center. They are both two separate networks with different roles.

Is this possible or do I need a new ASN number?

I believe that I CAN use my ASN number as long as the subnets advertised are different.

Thank you

cf

 

[jneiberger]

It's been a while since I've had to have my BGP thinking cap on, but it seems like this should be possible. Like you said, as long as the advertised prefixes are different, I can't think of a reason why you couldn't do this. I'm not sure it's recommended since ASNs should have a common single routing policy, but I think it's technically feasible.

 

[Cluebird]

Are you using the same ISP? Also, what registered address space? If you're connecting BGP with multiple ISPs you may have some difficulties using the same ASN. However, if it's the same provider, you should be able to use the same ASN...all you're doing is adding some new prefixes to the BGP table.

 

[optize]

You will be able to use your same AS, just make sure you are advertising unique IP space.