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

["Hemant Singh (shemant)" <shemant@cisco.com>]

-----Original Message-----
From: Ralph Droms (rdroms) 
Sent: Monday, July 21, 2008 11:21 AM
To: Rémi Denis-Courmont
Cc: Ralph Droms (rdroms); Alain Durand; Hemant Singh (shemant); v6ops@ops.ietf.org; Wes Beebee (wbeebee)
Subject: Re: New (-02) version of IPv6 CPE Router draft is available for review

> The only time the CPE router needs to use GUA is if it has never received a delegated prefix.  

Huh? Did you mean to say ULA?  Anyhow, the rest of your discussion does not map to the problem at hand.  Our problem is that I have bought this standalone CPE router from Best Buy (in the U.S.) and now I want to configure it at home via the web for the first time.  I have still not connected the router to the SP WAN.  I just connect an Ethernet cable between the CPE Router LAN interface and my PC and power up the router.  Now I need to configure the router via the web.  Initially we had suggested to use link-local address of the LAN interface to access the router from the web.  But Remi said that needs the full network name interface configuration in some browsers (we didn't need that in our test at Cisco) and also the access has some non-compliance with HTTP.  So then we said, we'll use a ULA.  At this juncture of the router operation/configuration, the router doesn't have any GUA.  A lot of folks in private emails to us have agreed to supporting ULA on the LAN interface(s) of the CPE Router.  We really don't think a coexisting ULA with GUA on the LAN in a problem for any data forwarding or source address selection.

We have one solution using ULA.  If a better solution is available for the problem described above, we are open to it.

Thanks.

Hemant

> Prefix delegation uses the same leasing mechanism as address assignment; if the WAN interface on the CPE router is not up, the CPE router can still use > the previously delegated prefix on the subscriber network.
> 
> So, as long as the CPE router has been connected to the ISP network at least once and has obtained a delegated prefix, there is no need for GUA.  To 
> avoid unnecessary complexity, I would strongly recommend that the CPE router be required to complete an initial prefix delegation operation when first 
> connected to the ISP before enabling any downstream interfaces.  Once that prefix delegation takes place, it is immaterial whether the LAN or WAN 
> interface comes up first.
> 
> This discussion brings up the problem of subscriber network operation
> - is it an explicit goal of this document that the subscriber network be able to operate even if the WAN interface is not up?  What are the expectations > for that unconnected operation and what services must the CPE router provide to meet those expectations?
> 
> According to the spec, the requesting router can only use the delegated prefix until the lease on the prefix expires.  We hadn't thought about relaxing > that restriction to allow the requesting router to continue to use the delegated prefix until it has a WAN connection back to the delegating router.

> - Ralph


On Jul 21, 2008, at Jul 21, 2008,10:57 AM, Rémi Denis-Courmont wrote:

> Le vendredi 18 juillet 2008 19:25:54 Alain Durand, vous avez écrit :
>> Supporting both ULA & GUA at the same time is also a source of  
>> complexity
>> and confusion. The key problem I see is with external referrals in
>> multi-party communications where some of the hosts are inside, and  
>> some are
>> outside. Mixing ULA & GUA can have complex consequences, and again
>> generates service call.
>
> Yeah. Broken RFC3484 implementations will do just that. But all  
> nodes (broken
> and non-broken RFC3484 implementations alike) will *break* without  
> ULA, until
> we have *instantaneous* 100%-reliable and 100%-available upstream  
> connections
> (which we will NEVER have). Without this, the network will simply  
> not work
> until the ISP connection is established (if ever), which is a total
> non-starter. Therefore, it seems like a total non-question that ULA  
> is the
> way to go.
>
>> Also, if I read the text correctly, if the WAN interface gets  
>> configured
>> first, no ULA are generated. Which leads to confusing situation  
>> depending
>> on whether the customer turns its modem on before or after its CPE.
>
> You may have a point here.
>
>> I would rather like the text to recommend to only use ULA when  
>> nothing else
>> is available and immediately renumber to GUA when those are acquired.
>
> And break existing connections on the local network? Total no go.
>
> -- 
> Rémi Denis-Courmont
> http://www.remlab.net/
>