About the address allocation convention between ISPs

Tue Jun 3 06:50:01 UTC 2003

Hi Teng,

>From my experience it is standard practice for the provider of the
Internet connectivity to provide the /30 network IP addresses for
connectivity between two networks.

There are exceptions such as when using unnumbered interfaces, peering
points that share a common subnet between multiple ISPs, and when two
networks flip a coin on private peering interconnects (where generally
neither side is the provider to the other) to determine who is going
to provide the interface IPs.

Darin

> 
> Hello everyone,
> 
> I have a question about the convention of address allocation between ISPs.
> If a smaller ISP tries to establish connection with its provider, does
> this small ISP configure one of the interface on its boarder router using
> an IP address obtained from the provider, or it is the other way around,
> that is, the provider uses one of the IP address belongs to the customer
> to configure the provider's boarder router?
> 
> I have this question because I am trying to identify the link between two
> organizations from traceroute measurements.   How the addresses are
> allocated will affect the identification of the inter-domain link by
> exactly one hop.
> 
> I am not sure if there is such a convention at all, or the address
> assignment is randomly decided according to the agreement between the
> customer and the provider?
> 
> Since I know there are many seasoned network professionals on this mailing
> list, I think it might be a proper question to ask here.  Would anyone
> kindly be willing to share your experience?  Thank you very much!
> 
> Sincerely
> 
> Teng
> 
> 
> 
> 