What is an AS Number?
An autonomous system number (ASN) is a unique number that's available globally to identify an autonomous system and which enables that system to exchange exterior routing information with other neighboring autonomous systems. According to Definition given by APNIC “An AS is a group of IP networks operated by one or more network operator(s) that has a single and clearly defined external routing policy”.
A unique ASN is allocated to each AS for use in BGP routing. AS numbers are important because the ASN uniquely identifies each network on the Internet.
There are two types of AS Numbers:
- Public AS Numbers: A public autonomous system number is used when the system is exchanging routing information on the public Internet with other autonomous systems. The routes will be visible on the Internet in Public AS number.
- Private AS Numbers: A private autonomous system number is used only if the autonomous system is communicating with a single provider via Border Gateway Protocol. The routes will not be visible on the Internet in Private AS number.
AS numbers are assigned in blocks by the Internet Assigned Numbers Authority (IANA) to regional Internet registries (RIRs). The appropriate RIR then assigns AS numbers to entities within its designated area from the block assigned by the IANA. Entities wishing to receive an ASN must complete the application process of their local RIR and be approved before being assigned an ASN. Current IANA ASN assignments to RIRs can be found on the IANA website.
- APNIC: RIR for Asia- Pacific region.
- RIPE NCC: RIR for European Region.
- AFRINIC: RIR for Africa Continent.
- ARIN: RIR for America & Caribbean region.
- LACNIC: RIR for Latin America region.
What are the benefits of having an AS Number?
Having own AS no. is always beneficial for Network in many ways, few are discussed below,
- Flexible Network Management.
- Benefits of Direct peering with IXP’s.
- Own Network Identity for External & Internal purpose.
- IP Address portability is one of the major benefits of using own IP address and ASN.
- Proper control of Traffic.
- Can Establish own BGP with ASN No.
How to obtain an ASN?
To qualify for an ASN: You must have either a unique routing policy or a multihomed site.
An AS-number must be obtained (leased) from one of the Regional Internet Registries (RIR's) [ARIN, LACNIC, RIPE NCC, AFRINIC, APNIC], but the RIR's receive their blocks of ASN from IANA.
Which registry you obtain your AS number from is based upon where your network resides physically, or where your organization is headquartered, and where will be connecting. You must apply to the RIR to obtain an ASN.
ASN's are usually provided for a 'container fee' which is a fancy way of saying that they will charge you money to open an account and place the AS number under your account. The registry needs to cover their operating expenses, and 'container fees' are one way they do that.
You will need to use an online registration page, or the downloadable form commonly called the ASN template to request your AS number (ASN).
What are the pre-requisites for applying for an ASN?
There is a limited number of ASN available, so the RIR's are very selective about whom they grant an ASN to. You will need to demonstrate the following:
- You must have a connection to more than one ISP (or will in the next 30 days). This is called being 'multi-homed'.
- You will be asked to specify the exterior routing protocol used to communicate with your ISP (this is exclusively BGP today)
- You will be asked to provide the AS numbers (ASN) of all your ISP's.
- You may be asked to provide the IP addresses of your ISP's routers to which you connect. You might get this information when the ISP provides your circuit and probably with the traceroute if the connection is already working.
- You and your ISP must already have an identity on file in the RIR's database.
- You must have blocks of IP addresses that need routing. You obtain IP addresses from RIR's as well.
- You must demonstrate a need to utilize BGP with an organizationally unique route policy OR be multi-homed.
You can also get a consultation through Mumbai IX for AS number. Our team will help you to get ASN with fewer efforts. To get the consultation for ASN: Email at email@example.com or Call on + 91 8879679816
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You can also apply for ASN directly by going to APNIC and IRINN websites.
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