Re: Why has RFC 4941 been designed in such a way, that it might causeaddress conflicts?

Timothy Winters <> Mon, 21 March 2011 15:17 UTC

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Subject: Re: Why has RFC 4941 been designed in such a way, that it might causeaddress conflicts?
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	The UNH-IOL has made a white paper from the event available on the IPv6 homepage.  As Hemant stated there were issues discovered around DAD and the need for it.


On Mar 20, 2011, at 7:09 PM, Hemant Singh (shemant) wrote:

> -----Original Message-----
> From: Brian E Carpenter [] 
> Sent: Sunday, March 20, 2011 6:49 PM
> To: Hemant Singh (shemant)
> Cc: james woodyatt;
> Subject: Re: Why has RFC 4941 been designed in such a way, that it might causeaddress conflicts?
>> Good idea, where's the wiki?
> Ah, none that I know of.  Also, I am only catching up to 6man email this weekend being busy in the week with v6ops emails.  If a wiki does not exist for such issues, we could start one.  Since our cable IPv6 home devices such as cable modems and IPv6 CE Routers (standalone or combined inside a modem) are assumed to provide no console, we have specified use of a DAD Proxy at the first-hop IPv6 router.  This first-hop router is also the access concentrator (a CMTS - Cable Modem Termination System) for cable broadband.  Note since the cable network is an end-to-end IP network, it is easier for cable to specify support for DAD Proxy at the CMTS.  DSL which is not end-to-end at the IP layer has more issues to deal with.  The reason is that a SP has console access to the CMTS and if the CMTS supports a DAD Proxy, the SP at least knows which home the failure has occurred in and take some action.  Without the CMTS supporting DAD proxy, the DAD failure for a modem or CE festers for an
>  error with the modem or CE dead in the water.   Of course, the home customer would call the SP in such a situation but it's better for the SP to be proactive to catch the error before any home user calls.  
> It's also interesting that even when the SP has detected a DAD Duplicate, what does the SP do besides shutting down one of the two nodes that clashed for the same IPv6 link-local address.  
> Thanks,
> Hemant
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