[c-nsp] IPv6 duplicate address

[Michael Smith]

Hello Hank:


> From: Hank Nussbacher <hank at efes.iucc.ac.il>
> Date: Tue, 27 May 2008 03:00:26 +0300
> To: <cisco-nsp at puck.nether.net>
> Subject: [c-nsp] IPv6 duplicate address
> 
> When we did some line testing and did some loop testing on the link we got:
> %IPV6-4-DUPLICATE: Duplicate address FE80::215:2CFF:FE87:B240 on POS11/0/0
> 
> petach-tikva-gp# sho ipv6 int pos11/0/0
> POS11/0/0 is up, line protocol is up
>    IPv6 is stalled, link-local address is FE80::215:2CFF:FE87:B240 [DUP]
>    Description: STM-16 to GEANT2 DE POP
>    Global unicast address(es):
>      2001:798:14:10AA::1E, subnet is 2001:798:14:10AA::1C/126 [TEN]
> The interface entered the stall state and did not leave stalled state until
> IPv6 addressing was disabled and reenabled on the link.
> 
> In:
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/
> 122t2/ipv6/ftipv6c.htm#10168
> Cisco states "An interface returning to administratively "up" restarts
> duplicate address detection for all of the unicast IPv6 addresses on the
> interface."  It would appear if an interface goes from up (looped) to up
> (non-looped), IOS does not check for dup addresses and the interface stays
> stalled.  Is this how it should be or is this an IOS bug (12.2(18)SXF11)?
> 
> I know I can use "ipv6 nd dad attempts 5" but wanted to know whether I
> should open a TAC case for this.
> 

Why not disable it entirely?  If you have a POS interface connected to
another one directly, couldn't you set it to 0?

Regards,

Mike