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

"Hemant Singh (shemant)" <> Sat, 14 November 2015 19:03 UTC

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From: "Hemant Singh (shemant)" <>
To: Gert Doering <>
Thread-Topic: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
Date: Sat, 14 Nov 2015 19:03:00 +0000
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Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]
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-----Original Message-----
From: Gert Doering [] 
Sent: Saturday, November 14, 2015 1:51 PM
To: Hemant Singh (shemant)
Cc: Gert Doering; Owen DeLong;
Subject: Re: [v6ops] DAD again [was: draft-ietf-v6ops-host-addr-availability discussion]

>But: the outbound interface will NOT use the lo0 source address for the ND activity.  It will use the *interface* IP for ND, and the link-local one for that.

I already said that in my previous email.

>Surely you're not asking for a router to do DAD for every single IPv6 address that could be coming *through* that router?

No.    A router forwards packets and if the router egress interfaces fails L2-destination lookup, the interface issues a L2 address resolution.   Note, however, once a source IPv6 address of a lo interface is active to send data and the downstream LAN segment somehow has a dup, the dup issue cannot be fixed unless the router support ND Proxy which can respond.

>> I did issue "clear ipv6 neigh" on my router to clear the neighbor cache to force a ND address resolution.  The ND address resolution NS can use the link-local address or the global address of the outbound interface for sourcing the NS.

>"the global address of the outbound interface" is NOT the lo0 source address.

Right - what is your point?  Please also see rfc5942 and section 6.  No source IPv6 address in a ND message can be used to make on on-link determination.