RE: new draft on IPv6 CPE router available for review

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

Remi,

Please see in line below between "<hs> and </hs>". 

-----Original Message-----
From: Rémi Denis-Courmont [mailto:rdenis@simphalempin.com] 
Sent: Monday, July 07, 2008 2:36 PM
To: Hemant Singh (shemant)
Cc: Wes Beebee (wbeebee); v6ops@ops.ietf.org
Subject: Re: new draft on IPv6 CPE router available for review

Le lundi 7 juillet 2008 21:01:47 Hemant Singh (shemant), vous avez écrit :
> http://www.ietf.org/internet-drafts/draft-wbeebee-ipv6-cpe-router-01.t
> xt

   Note that if the home does not cascade CPE routers, then ULA's are
   not needed for the LAN interfaces, since link-local addresses are
   sufficient for configuration.  After the WAN interface initializes,
   then the LAN interface(s) can acquire global unicast addresses.

This is simply not true. Most (at least quite many) IPv6 applications are incapable of using link-local addresses, owing to the peculiar way the socket API deals with them. Namely, it requires that the socket address scope ID be set. The only way to have fully operational LAN communications is to keep an ULA prefix always, regardless of cascading. And it should preferably remain present even if the WAN connection has succeeded, so that:
 - pre-existing connections don't break needlessly when the WAN goes up,

<hs>
We know a web browser can access the CPE Router on the same IPv6 LAN segment using a link-local address - no denying that. Please tell us what application that uses socket API is needed during manual configuration when the CPE Router is being configured via the web? Or what else needs to be done on the CPE Router besides manual configuration (via web) for which sockets API break because the LAN interface is assigned only a link-local address?

As a side note, we do say in the draft once ULA is configured on the LAN interface(s), the ULA co-exists with GUA (Global Unique Address).  The GUA gets assigned to the LAN interface(s) later when the WAN interface completes acquisition of IA_PD.
</hs>

Hemant & Wes.


 - boxes can easily check if a host is "outside" or "inside",
 - connections don't break if the delegated prefix changes.


--
Rémi Denis-Courmont
http://www.remlab.net/