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Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]

Gert Doering <gert@space.net> Fri, 13 November 2015 14:08 UTC

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Date: Fri, 13 Nov 2015 15:08:30 +0100
From: Gert Doering <gert@space.net>
To: "Hemant Singh (shemant)" <shemant@cisco.com>
Message-ID: <20151113140830.GT89490@Space.Net>
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Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
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Hi,

On Fri, Nov 13, 2015 at 01:58:04PM +0000, Hemant Singh (shemant) wrote:
> >One wouldnt care about DAD on loopback interface, because it's not noise on a wire, and it's not time consuming.
> 
> So how will you deal with a duplicate IPv6 address configured on a 
> loopback interface?  

We don't care.  Loopbacks imply a routing table entry somewhere to make
the packets actually reach this host - and this should ensure it's reaching
only the intended host (or you have dns-root style anycasting)

> As I said in my example, a router is using the IPv6 address on a loopback interface to source packets and a duplicate is detected - the network breaks down.

The upstream router should reject packets coming from a downstream which
is not permitted to use an IPv6 address.

Otherwise, there is no way to ensure uniqueness on non-directly-connected
interfaces - think "loopback on a router on the other side of the planet".

Gert Doering
        -- NetMaster
-- 
have you enabled IPv6 on something today...?

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