how many BGP routers, how many ASes

William Herrin herrin-nanog at
Wed May 13 12:46:29 CDT 2009

On Wed, May 13, 2009 at 11:53 AM, Irfan Zakiuddin
<irfan.zakiuddin at> wrote:
> What I want to know is roughly how many :
> 1.  ASes there are in the world today?

Hi Irfan,

A little over 31,000. See

> 2.  BGP routers there are, for intra-domain as well as inter-domain routing,
> in total in the world?

I know of no authoritative source for this information. I used 150k
for my estimate when I prepared last year; that fell more
or less in the middle of the educated guesses I got here on nanog and
in the other places I asked.

Figure every AS must have at least one BGP router, the vast majority
will have at least two, many will have more than two, and at least
some will have more than 100. Figure also that there are fewer BGP
routers in use than there are prefixes in the table. Gives you a lower
bound of around 70k and an upper bound around 290k.

> 3.  BGP routers do the largest ASes have?

Decide what you mean by largest, identify which AS that is on the CIDR
report and then go ask them.

> Really interesting would then be to say either how fast the above numbers
> are growing, or to give estimates for what the answers to 1-3 will be in 5
> years time.
Figure 7 offers a handy graph from which you should be able to project a trend.

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

More information about the NANOG mailing list