Re: New (-02) version of IPv6 CPE Router draft is available for review

[Alain Durand <alain_durand@cable.comcast.com>]

Hemant,

You missed the phrase "*with* address referral" in my response.

Say A & B are inside their home and use ULA & GUA. C and D are within
another home and are also using ULA & GUA.

Now, A B C & D enter a 4 way communication where they initially exchange the
addresses of their pier.
If A passes C the ULA and GUA of B, C might prefer to use B's ULA because of
address selection rules and C->B communication would fail or worse, go
somewhere else.

There are multiple variants of this. The point is that you cannot expect
apps that passes addresses to be smart enough to know about ULA & GUA.

BTw, using DNS does not help at all if you include both ULA & GUA AAAAs in
your zone...

  - Alain.


On 7/22/08 1:17 PM, "Hemant Singh (shemant)" <shemant@cisco.com> wrote:

> Alain,
> 
> Sorry I don't understand.  If any node in the home using an ULA sends a packet
> out the WAN interface of the CPE Router, the src-addr of the packet used is
> the GUA before the packet heads out of the node because, as we said in our
> draft, GUA has larger scope.  So any multi-party host on the Internet sees
> only the GUA.  I will need a specific example to show me how multi-party
> communications will break down with ULA and GUA configured on an interface of
> any node in the home behind the CPE Router or if ULA and GUA is configured on
> the LAN Interface of the CPE Router.
> 
> Thanks.
> 
> Hemant
> 
> -----Original Message-----
> From: Alain Durand [mailto:alain_durand@cable.comcast.com]
> Sent: Tuesday, July 22, 2008 11:48 AM
> To: Hemant Singh (shemant); Ralph Droms (rdroms)
> Cc: Mark Townsley (townsley); Jimmy Chuang (cchuang); Rémi Denis-Courmont;
> v6ops@ops.ietf.org; Wes Beebee (wbeebee)
> Subject: Re: New (-02) version of IPv6 CPE Router draft is available for
> review
> 
> On 7/21/08 12:43 PM, "Hemant Singh (shemant)" <shemant@cisco.com> wrote:
> 
>> I have repeatedly said, I am not convinced the ULA gets appreciable
>> complexity into the CPE Router. Our section 5.5.1 has clearly outlined
>> any complexity and shown it's minimal.  The ULA fixes a very common
>> problem for the CPE Router which is configuring the router without any
>> SP access - the problem is not a corner case.
> 
> Hemant,
> 
> 2 party communications in the presence of mixed ULA & GUA work ok, given
> proper default address selection rules.
> 
> Multi-party communications *with* address referral do not work in the general
> case in such a mixed environment, regardless of default address selection.
> 
>   - Alain.
> 
>