[v6ops] 6204bis and WAN disappearing

["Dan Wing" <[e-mail]>]

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the WAN link fails (should the globally scoped prefix be withdrawn on the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.

-d