Re: [v6ops] 6204bis and WAN disappearing

Le 2012-02-22 à 00:49, Dan Wing a écrit :

> Reading draft-ietf-v6ops-6204bis-05, I couldn't determine what the CE router
> should do if, after it acquires an IPv6 prefix from its WAN interface, the
> WAN interface later goes down.  Requirement G-4 in the specification
> (http://tools.ietf.org/html/draft-ietf-v6ops-6204bis-05#section-4.1)
> requires the CE router (immediately?) withdraw the prefix on the LAN
> interface, but if this text (from draft-ietf-v6ops-6204bis-05) is true:
> 
>  1.  Link-local addresses may be insufficient for allowing IPv6
>      applications to communicate with each other in the end-user
>      network.  The IPv6 CE router will need to enable this
>      communication by providing globally scoped unicast addresses or
>      ULAs [RFC4193], whether or not WAN connectivity exists.
> 
> then withdrawing the globally scoped unicast addresses will break
> communication within the home.  This means if my WAN link goes down, IPv6
> streaming between my NAS and my speakers breaks which ruins my dinner party.
> 
> 
> Can draft-ietf-v6ops-6204bis be more precise describing what happens when
> the WAN link fails (should the globally scoped prefix be withdrawn on the
> LAN?  Immediately?  After several days?  What about after a reboot of the
> CPE?), and can it be more precise to discuss if the CE router has to provide
> a globally scoped unicast address or has to provide ULA, or has to provide
> both.  As written, devices in the home that rely on the globally-scoped
> address will fail if the WAN link fails, and

> it should not be necessary for
> host and CE router implementers to read the tea leaves of
> draft-ietf-v6ops-6204bis that ULA is necessary for successful operation of
> home network equipment when the WAN fails.

+1

If the WAN link fails, its last assigned global prefix can advantageously be used locally until the link comes back:
- If it comes back with the same prefix, great.
- If it doesn't, consequences of a prefix change have indeed to be supported, but for a reason that has no relation to link failure.

Now, if an IPv6 LAN starts operation before having any WAN access, any prefix could work that is never routed to any customer site. 
It could be fd00::/48 (neither a ULA prefix, nor a publicly routable prefix, ref the ULA RFC4193).

RD

> 
> -d
> 
> 
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