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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/