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

Timothy Winters <twinters@iol.unh.edu> 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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From: Timothy Winters <twinters@iol.unh.edu>
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Hello,
	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.

Regards,
Tim

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

> -----Original Message-----
> From: Brian E Carpenter [mailto:brian.e.carpenter@gmail.com] 
> Sent: Sunday, March 20, 2011 6:49 PM
> To: Hemant Singh (shemant)
> Cc: james woodyatt; ipv6@ietf.org
> 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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