ISP support for use of 4-byte ASNs in peering

Michael Hare michael.hare at
Tue Aug 9 14:45:08 UTC 2011

While attempting to focus on ISPs there is still [unbelievably] a vendor 
support issue.  You may consider this a procurement failure, but the 
fact remains that some products [Cisco me3400e] have yet to implement 


On 8/9/2011 9:24 AM, Nick Hilliard wrote:
> On 09/08/2011 14:47, John Curran wrote:
>>    At ARIN, we are still having parties returning 4-byte ASN's (seeking 2-byte instead),
>>    indicating that the 4-byte ones are not sufficiently accepted in peering to be usable.
>>    This is obviously a less than desirable situation, and it appears that it is not trending
>>    towards resolution at this time.
> At INEX, we see 60% of IXP connections which can handle ASN32 natively.
> However, INEX is a small IXP and I haven't seen similar figures from other
> IXPs which could validate this 60/40 split.
> Having said that, in the IXP world most new service providers connect into
> route servers, so there is often no perceived requirement for direct
> ASN32->ASN16 interconnection - the intersection of new service providers
> and ASN32 holders is quite large.  And if you really want a bilateral
> peering relationship, there's no reason not to use AS23456.
>> Thoughts?
> - interior BGP community management is great fun with an ASN32, oh yes.
> - i don't have much sympathy for people who whine about not being able to
> support ASN32 peerings.  There is no good reason for this these days.
> - from personal experience, I understand why ASN32 is less popular.
> However, it's certainly usable.
> Nick

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