32bit/4byte AS Number

Unanswered Question
Jul 27th, 2008

Any idea when will Cisco release the IOS that supports 32bit/4byte AS Number?

I received this from APNIC http://www.apnic.net/news/2008/0725.html

From what I understand, to date, Cisco has not release IOS that supports 32bit/4byte AS number except for IOS-XR?

I have this problem too.
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guruprasadr Mon, 07/28/2008 - 00:58

HI Medan,

Thanks for the NEWS posted.

Let's wait for some Experts / Cisco Emp.. reply on the POST with exact details.

Best Regards,

Guru Prasad R

Danilo Dy Mon, 07/28/2008 - 01:20

Hi Guru,

Other RIRs (ARIN, RIPE, AFRINIC, LACNIC) may have sent/post notification as well.

Although there is backward compatibility from 32-bit to 16-bit ASN. I want to know what is the impact of 32-bit ASN number to 16-bit ASN BGP routers. For example, will a 16-bit BGP router accept routing updates from a 32-bit ASN? It says it will use some translation and tunneling mechanism. However, this worries me...


If BGP encounters something unexpected in the translation back from the "old" to the "new" world, then the only casualty is speed of routing convergence, where it may take a number of additional AS hops for a potential routing loop to be detected and removed.

So, even if you do absolutely nothing in your 16-bit "old" BGP routing domain, Internet-wide routing will still work, and reachability information will still be propagated in useful forms. Nothing will 'break'. But there are some things to check, and maybe alter, in the larger environment of your operational support framework.



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