unavailable virtual gateways

[Martha Steenstrup <[e-mail]>]

Hi Woody,

The set of currently unavailable virtual gateways can be used by the
route server to flush routes including those virtual gateways from its
route database.  That was its original purpose.  As you said, the
prototype implementation doesn't do this.  However, I expect that we
want this feature in the implementation.

Yes, the list of the currently unavailable virtual gateways contained
can be derived from virtual gateway information contained in the
Configuration message and in the Dynamic message.  However, as we
discuss in section 4.2.1 of the protocol specification, we made a
decision to make virtual gateway availability information explicit in
the Dynamic message, because it meant less processing of the routing
information messages, searching for which virtual gateways were up and
which were not.

If, upon revisiting the implementation, you feel that the cost to
derivce the unavailable virtual gateways isn't a big deal, then let's
remove the unavailable virtual gateway list from the Dynamic message.
Let me know what you think so that I can adjust the protocol
specification document properly.

Yes, the path control protocol doesn't need to receive a copy of the
list, because paths with broken virtual gateways will be torn down and
removed from the path agent's cache of routes.

m