[Prolixium]

I always figured that 4-digit and 5-digit ASNs were "cool" to a certain crowd but seeing them at the bottom of this auction page just seems like lunacy.

Sure, IPv4 blocks have reputation but I've never heard of the equivalent for ASNs, especially ones that have a small number of digits.

32-bit ASNs are very easy to come by from all registries and there are lots of them. Most all BGP implementations have supported them for a long time so there shouldn't be a reachability issue.

Am I missing something? Is this just plain vanity?

[kloch]

> Sure, IPv4 blocks have reputation but I've never heard of the equivalent for ASNs, especially ones that have a small number of digits.

tl/dr; ASN's are highly visible to network engineers, it's your identiy as a network. Lower/shorter numbers are "better", at least to some people.

All of the 4 digit ASN's were originally allocated in the 90's, during the initial ISP/dot com boom and are often viewed as a sign of being an established player, or just "cool". Almost all the major ISP's use 3 or 4-digit ASN's: 3356 = Level3/Centurylink/Lumen, 701 = Verizon, 174 = Cogent, 1299 = Telia (now Arelion), 2914 = NTT, 6453 = TATA, etc. Even Netflix snagged 2906 when ARIN suddenly recycled a bunch of 4-digit ASN's in 2009.

If you are an ISP, every one of your BGP customers and peers has to configure a BGP session with your ASN so it has maximal visibility in that use case. Even if you are just peering on public IX's, every peer will see your ASN when they configure the session or do "show bgp sum".

These days there is a similar effect though less dramatic for 5-digit ASN's, and that is reflected in the lower asking prices.

What surprises me is how fast the 5-digit ASN's were selling (look at recent sales). In the ARIN region you can get a 5-digit ASN just for asking when you apply, otherwise they assign a 6-digit by default most of the time. The takeaway from this is that people are paying for a definite, specific number that they like rather than take their chances with a random assignment from ARIN.

[merlyn]

As someone that does run an ISP and helps run an IXP, it matters nothing to me if somebody has a 32-bit ASN vs a 16-bit ASN.

Sure, I can see 6939 or 701 and know instantly who that is, but in the end, it matters nothing for the other 98% of ASNs I don't recognize on sight and who they might be behind them.

Anybody that is paying money for a "vanity" ASN is just doing it for self-ego stroking. To the people doing the work, it doesn't matter one iota.

[mrweasel]

> Sure, IPv4 blocks have reputation

IPv4 blocks are actually useful. If you run a datacenter it makes sense that you'd try to get something bigger than a /24. Why you'd care about having a 4 digit ASN I don't understand... easier to remember?

[Sesse__]

Because BGP doesn't support ASN numbers larger than 16 bits; the 32-bit support is a pretty nasty hack, and for a long time, lots of equipment would not support it.

[kloch]

Running BGP with 4-byte ASN's is well supported by all major vendors by now. The issue is policies that use ASN:XXXXX communities which is 2-byte:2-byte.

There is an RFC to extend this to 4-byte for the ASN part but that is not widely supported yet.

https://community.cisco.com/t5/routing/how-to-set-up-in-the-...

https://datatracker.ietf.org/doc/rfc5668/

For small enterprises/end users (that might not define their own communities at all) this is usually not a problem but for larger networks or ISP's you end up with a compromise where you are truncating the 6-digit ASN or using a private ASN, neither of which are desirable. Arin let's you request a 2-byte ASN and if they have one in inventory (they usually do) you can get it.

[icedchai]

32-bit ASNs have been a thing for close to 15 years now. Any older equipment likely wouldn't be able to handle a full routing table anyway.

I remember setting up BGP in 1998 for a local mega corp. They had 2 full T1s! I think there were only 50K routes.