I see here that even some organisation/universities have bought ASN which are located at single location. What benefit they will get by buying ASN ? Is it compulsory to buy ASN if I have to buy some public IP's from my ISP ?
Example :
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Organizations get ASNs when they need to exchange routes via BGP with other organizations.– Ron Maupin ♦Aug 21, 2019 at 13:32
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Thnx @RonMaupin but why would anyone want to do it ? They can get the routing info by connecting their router to ISP router too and ISP router can BGP with other– Number945Aug 21, 2019 at 13:33
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2You are looking at this from a home networking perspective, where the home network uses an address from the ISP. If the organization wants to advertise its networks via BGP to the ISP and the greater world, then it needs an AS number. Thje organization could also have multiple connections to various ISPs (this is a normal situation), and it would like to choose the best path out.– Ron Maupin ♦Aug 21, 2019 at 13:36
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1Also, remember that the original ISPs were universities. The Internet originated from a government/university experiment.– Ron Maupin ♦Aug 21, 2019 at 13:43
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1Most large organizations own their own IP networks, and they must advertise those networks so that people outside can get to the networks. If Google did not advertise its networks to the various providers, you could not get to Google because there would be no path to Google networks. The same applies to a university. If you wanted to get to the university network (web site, etc.), the Internet must know how to get packets to the university, so the university network(s) must be advertised out to the Internet.– Ron Maupin ♦Aug 21, 2019 at 15:07
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1 Answer
An Autonomous System number (ASN) is required to use the BGP protocol. An organization can get a registered ASN, or it can use a private ASN (similar in concept to private IP addresses).
ISPs use BGP to exchange routing information with other entities. So if your organization wishes to exchange routes with your ISP, you will need to run BGP, and you will need an ASN.
If the routes you advertise are registered to you (i.e., provider-independent space), you will need a registered ASN. If you are using address space provided by your ISP, you may be able to use a private ASN. That is something you would negotiate with your ISP.
An organization that has only a single connection to one ISP, in most cases, doesn't need to use BGP, and can simply use static routing.
answered Aug 21, 2019 at 13:41
