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

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

This has not been my experience using multiple addresses. You may want to
read some of my earlier work:

http://www.ietf.org/rfc/rfc4943.txt?number=4943
http://www.watersprings.org/pub/id/draft-roy-v6ops-v6onbydefault-01.txt

  - Alain.


On 7/22/08 5:35 PM, "Hemant Singh (shemant)" <shemant@cisco.com> wrote:

> Sure thing.  But I would expect that node C would receive the ICMPv6
> Destination Unreachable before TCP times out, wouldn't you?
> 
> Hemant
> 
> -----Original Message-----
> From: Alain Durand [mailto:alain_durand@cable.comcast.com]
> Sent: Tuesday, July 22, 2008 5:10 PM
> 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
> 
> Hemant,
> 
> Thank you for looking into this.
> The issue is that C's connection to B may have to wait for TCP timeout, which
> is 3 min. This is long. Too long.
> 
>   - Alain.
> 
> 
> On 7/22/08 5:01 PM, "Hemant Singh (shemant)" <shemant@cisco.com> wrote:
> 
>> Alain,
>> 
>> Very sorry, I missed your "*with* address referral" phrase.  Thanks
>> for providing the example.  Here is the analysis:
>> 
>> Yes, if C tries to communicate with B using B's ULA for destination, C
>> will also slap its ULA on the packet src address.  Thereafter before
>> the CPE Router WAN interface egresses the packet, the router has to
>> comply to ULA forwarding rules.  As per section 4.3 of RFC4193, the
>> CPE Router will drop the packet (unless the router is explicitly
>> configured for a route to destination ULA) and send an ICMPv6
>> Destination Unreachable to C. Here is the text from the RFC.
>> 
>> [Site border routers and firewalls should be configured to not forward
>> any packets with Local IPv6 source or destination addresses outside
>> of the site, unless they have been explicitly configured with routing
>> information about specific /48 or longer Local IPv6 prefixes.]
>> 
>> I don't expect the CPE Router to be supporting a site connected to
>> another ULA site so the question of any configuration on the CPE
>> Router for a neighbor ULA site is out of the question.  Since C gets
>> some error indication, the app then needs to figure out fixes in its
>> implementation.
>> 
>> Sorry, I don't see this as rustication to change the CPE Router permanent
>> ULA.
>> Some brain-dead apps need fixing.  I need more people to speak up and
>> give their opinion.  I am still open to change.
>> 
>> Thanks.
>> 
>> Hemant
>> 
>> -----Original Message-----
>> From: Alain Durand [mailto:alain_durand@cable.comcast.com]
>> Sent: Tuesday, July 22, 2008 1:25 PM
>> 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
>> 
>> 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.
>>> 
>>> 
>> 
>> 
> 
>