Issues with 4-octet BGP AS and Akamai?

Greg Gombas -X (grgombas) grgombas at
Tue Nov 14 02:36:04 UTC 2017

Hello BGP and/or Akamai experts,

Has anyone come across issues with using the new 4-octet BGP AS number format and reaching websites hosted by Akamai?

One of my customers currently uses the AS number of one of their partner companies, which is in the standard 2-octed AS format. They were recently assigned their own AS which is in the 4-octet AS format.

When they advertise their networks using the 2-octet AS number everything works fine, they can browse to all websites and all their outbound and inbound internet traffic works perfectly.

However when they stop advertising their networks using the 2-octet AS and advertise their networks using the new 4-octet AS number, they lose reachability to a number of websites, all of which seem to be hosted by Akamai, including<>,<>, and a number of others. Websites that are not hosted by Akamai work just fine.

We checked their route advertisements from several looking glass servers and the routes seem to be propagating properly, albeit there may be a number of older routers still out there that don't understand the new 4 octet BGP AS format.
For example, their AS shows up as AS_TRANS 23456 on some looking glass routers.

My understanding is the 4-octet ASN's have been out for quite some time now, so any interoperability issues should have been resolved by now. But could there be some old BGP speakers who don't understand the new format or the translated AS 23456 format and drop the routes?

Has anyone experienced similar issues when using the new format 4 byte BGP ASN's?

Any thoughts on who at Akamai we can speak to in order to troubleshoot this further?



Gregory Gombas
CCIE# 19649 - R&S
Network Consulting Engineer
Advanced Services
grgombas at<mailto:grgombas at>
Office: +1-212-714-4497
Mobile: +1-201-675-9457

Cisco Systems Limited
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