RE: I-D Action: draft-ietf-6man-enhanced-dad-01.txt

["Hemant Singh (shemant)" <[e-mail]>]

Ray,

Please see responses below for the use cases you raised.

-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf Of Ray Hunter
Sent: Saturday, September 08, 2012 7:18 AM
To: [e-mail]
Cc: 6man Mailing List
Subject: I-D Action: draft-ietf-6man-enhanced-dad-01.txt


>What should a receiver do if a node receives its own NS(DAD) on another 
>interface other than the source interface which is performing DAD?
>[use case: two L3 interfaces on one node connected to one common L2 
>link, where one interface re-initialises or wants to use a new temporary 
>address and thus performs DAD. That isn't a loopback condition or error 
>condition at all if that NS(DAD) packet is received on the other interface.]

>I think the text in section 4.3 could do with some clarification on 
>sending and receiving interfaces.

For your use case, the issue won't happen during DAD for the global IPv6 address assigned to a L3 interface.  A node won't be able to configure two separate interfaces with the same IPv6 global address. The two L3 interfaces have different IPv6 global address(es) and for global address(es) each L3 interface is a separate link-local domain.  It's only for the link-local address that the two L3 interfaces may share one link-local domain.  Say, the two L3 interfaces are int1 and int2.  Then if int1 issues a NS(DAD) for the link-local address, and an identical NS(DAD) is received on int2 the implementation has to deal with DAD duplicates for all interfaces in the same link-local domain.

>There are high availability situations that intentionally cause 
>collisions of IID and a virtual IPv6 address [e.g. HSRP IPv6].
>Do these need to be explicitly excluded from this draft? Or is that 
>someone else's problem?
>[There is a table on the relevant manufacturers website labelled Table 
>19 "HSRP and IPv6 ND Addresses " which shows when the virtual MAC/ 
>Virtual IPv6 is used for messages. AFAIK DAD is never performed on the 
>virtual address, as prevention of duplicate addresses is handled in the 
>HSRP protocol itself]
>
>There are high availability cases where multiple NICs are connected in 
>parallel [Teaming].
>Does this require any special treatment? Or simply a clarification that 
>DAD is performed on the resulting virtual NIC interface or LACP bundle 
>rather, than individual physical links? Or is this plain obvious?

I think it's obvious.  The manufacturer has also included documentation highlighting which IPv6 set of addresses are skipped for DAD.  Note, there are other networks where DAD is disabled such as a point-to-point links.

Regards,

Hemant