General Understanding of ASN Relation to ISP

[cj95029]

Hello,

I have a very rudimentary understanding of the Internet/networking and am looking to learn more. After looking up an IP address associated with a VPN, I noticed that the ISP associated with the IP address was different from the ASN (I have attached a picture to this discussion as an example of what I found during an IP lookup). From my understanding, IP subnets are routed to an ASN, which is then owned by an ISP. However, I was unaware that the ISP could be a different company than the ASN. If this is incorrect, please correct me. 

If this is the case, is it possible for a RIPE IP address to be hosted by an ARIN-associated ASN?

Thanks

[vencislav.metev]

Hi,

In public internet space you have public addresses for communication. To route all the traffic you can`t use static routes. Here it comes BGP. It is used for exchanging dynamic routing between different entities. By entity I mean company/ISP or someone else who paid for the AS number and public address. This paid services (AS number and public IP address - I`m not sure if they are actually a service...) are provided by ISP which they buy from another bigger provider. On top there are different organizations like ARIN,APNIC,RIPE which are responsible for management of the public addresses and AS numbers. They provide to ISPs the subnets` ranges and AS numbers

Regards,

Ventsi

[Georg Pauwen]

Hello,

basically, there is a fairly large secondary IPv4 market in the ISP world, where ISPs are transferring unused IPv4 addresses amongst themselves. That is why you can see exactly what you are observing. A lot of ISPs are still somewhat reluctant to make the switch to IPv6, so by buying and selling unused IPv4 addresses from and to each other, that transition can be put off.

ISPs can do a lot with just a few IP address, stuff like Carrier Grade NAT (also called large-scale NAT), where small pools of IP address can be shared amongst many customers, is one of these techniques.