Same BGP AS but different country

Routing & Switching BGP
1

Dear team,

Can I have same AS for different country ?

let’s say I have in india AS 100 and in JAPAN same AS 100. but prefix are different ?

2

Hello Mehul

In general, the AS’s are handed out to specific corporations (Tier 2 and Tier 3 ISPs) to administer. In most cases, corporations function within the borders of their own countries. The general rule is, AS’s remain within the physical boundaries of a country. This is not a hard and fast rule, and can (and often is) broken. However, to answer your specific question, the answer is no, you would never see the same AS span from India to Japan.

Having said that, it is technically feasible to have that done, but it is not desirable or functional.

There are several sites that keep track of global AS’s such as http://as-rank.caida.org/ that you might find interesting.

I hope this has been helpful.

Laz

3

Dear Laz,

Thanks for your response. I m still confused. can you please check below tracerouter from UK intances to Japan Instnace. this are linode instance and i am testing AS from UK to JAPAN. End the end to JAPAN i can see same AS number are used for as in UK so confused so how it’s possible. is it due to network ranges changes ?

4

Hello again Mehul

After a little more research, I stand corrected in my previous comments. Although AS’s are in general confined to specific corporations in specific countries, there are Tier1 ISPs that have AS’s that serve as the backbone of the Internet. These are required to span countries and continents to be able to transfer info from one area of the world to another. Take a look at the information about AS 6435 at the following site: http://bgp.he.net/AS6453. Specifically, AS 6435 belongs to Tata Communications which is a tier 1 ISP and has several nodes worldwide. Its country of origin is the US, and so the AS has been issued by the American Registry for Internet Numbers (ARIN) but its geographical coverage can go beyond the US.

You can view detailed information about all of the AS’s in the world and see where their exchanges are.

I hope this has been helpful!

Laz

1 Like