RE: new draft on IPv6 CPE router available for review

["Wes Beebee (wbeebee)" <wbeebee@cisco.com>]

Note that while it is possible to use link-locals to configure the CPE Router (when they are not cascaded), it may be inconvenient to do so as you point out.  Therefore, we will remove the following sentence from the draft:

"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."

Thanks,
- Wes and Hemant

-----Original Message-----
From: Rémi Denis-Courmont [mailto:rdenis@simphalempin.com] 
Sent: Monday, July 07, 2008 4:45 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 23:22:49 Hemant Singh (shemant), vous avez écrit :
> -----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?

I tried two different browsers.

In both of them http://[fe80::211:11ff:fe12:3456]:8080/ resulted in a connection failure. I had to type http://[fe80::211:11ff:fe12:3456%eth0]:8080/ which violates the HTTP URI spec, and requires that I know how my network interface is called.

Also, any protocol that embeds IPv6 addresses will fail, since the scope specifier is host-specific such that there is no sane way to convey it across the network.

> 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>

I am well aware of that.

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