Re: IPV6 Duplicate Address Detection(DAD)

Good evening team,

Anantha, dup global addresses will not create any issues with the interface
coming up or with the control protocol traffic. Team, ... keep me honest
here. ;-)

In a lab test I just did, I configured two routers on the same segment to
have dup global addresses and unique link local. I then added some loops to
one of these and configured OSPF on everything.

I then configured IPv6 and OSPF on another router from another segment; one
hop away. Since everything is associated with link local, there was not any
problems with connectivity, routing updates and or pings. I could get to
the loops on the correct router, and at first it appeared that dups did not
matter much at all.

Interesting to lab this out and understand where a routing loop can occur.
Since clients get their addresses from DHCP or autoconfig, having dups in
your network could cause two segments in different parts of the network to
have an identity crisis / overlapping address space.

Apart from this, no worries. Have a great night,

Andrew

On Thu, Sep 17, 2009 at 11:00 PM, Anantha Subramanian Natarajan <
anantha.natarajan_at_gravitant.com> wrote:

> Hi All,
>
> Would like to confirm about the IPV6 Duplicate Address Detection(DAD), DAD
> would detect duplicate addresses ,if exist for both link local address and
> global ipv6 unique address on a link.Is that right ?..If so,in the below
> show output,if it mentions ipv6 is stalled,I am understanding that a
> duplicate link local address is been detected on the link and ipv6
> processing on the interface is disabled.Please correct me if I am wrong on
> this.
>
> My question is ,if DAD detects duplicate address on the global ipv6 address
> on the link,does that also will lead to stalled interface,if so,how we can
> distinguish between link local and global ipv6 duplicate address detection.
>
> Kindly help me to understand the above.
>
> Router# show ipv6 interface ethernet 0
> Ethernet0 is up, line protocol is up
> *IPv6 is stalled*, link-local address is FE80::1
>
> Thank you very much for the help
>
> Regards
> Anantha Subramanian Natarajan
>
>
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-- 
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net