Using 32 bit ASN numbers

Pender, James James.Pender at
Fri Aug 29 10:44:51 CDT 2008

These are the dates I have for Cisco platforms:

IOS XR 3.4 - September 2007 
IOS 12.0(32)S11 - November 2008 
IOS 12.2SRE - December 2008 
IOS 12.5(1)T - April 2009  

-----Original Message-----
From: andy lam [mailto:anwalam at] 
Sent: Friday, August 29, 2008 11:29 AM
To: nanog at; Brian Raaen
Subject: Re: Using 32 bit ASN numbers

Cisco IOS XR Software Release 3.4.0 adds support for BGP Authentication Key Chaining, BGP 4-Byte Autonomous System Number (ASN), and BGP Next Hop tracking enhancements.
BGP 4-Byte ASN-Increases the range of supported autonomous systems from 2 bytes to 4 bytes to scale with expected Internet growth.
12.2SR* is supposed to be in late 2008, but has not yet been announced publicly.
Juniper it's in JUNOS 9.1 as farr as I can tell.

--- On Fri, 8/29/08, Brian Raaen <braaen at> wrote:

From: Brian Raaen <braaen at>
Subject: Using 32 bit ASN numbers
To: nanog at
Date: Friday, August 29, 2008, 11:04 AM

I am doing some research for our company regarding 32 bit ASN numbers.  I am 
trying to locate information about vendor and service provider support.  In 
particular I have not been able to find what Cisco IOS image I would need to 
load on our router to support 32 bit ASN's.  I also want to know what 
experience people have had with service provider support of 32 bit ASN's

Brian Raaen
Network Engineer
braaen at


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