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

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

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.
>> 
>> 
> 
>