draft-ccamp-gmpls-overlay-00.txt

["Adrian Farrel" <afarrel@movaz.com>]

Hi folks,

A couple of questions about sections 5 and 6.

Can we "restore" Notify_Request functionality on the other side of the core?
This is distinct from dropping the Notify_Request from the Path/Resv message
because we want to allow the tail part of the LSP (i.e. that part beyond the
downstream Edge Node) to send Notifies.

There would appear to be two cases.

First the core does not care about Notify messages within the core. In this case
the Notify_Request can be left in place. Core nodes can simply fail to send
Notify messages.
(The alternative - that all nodes that provide routes out of the core can fail
to forward Notifies - should be rejected because Notifies may need to be sent
across the core.)

The second case is more complicated. The core also wants to use Notifies,
reporting errors to the ingress/egress core nodes. Under normal circumstances we
would simply replace the Notify_Request on the way through, but how will we
restore the Notify function?

a. Introduce a 'stack' of Notify requests
b. Have Notifies forwarded as...
The core node next to the edge node that receives a Notify_Request from the edge
node replaces it with its own Notify_Request. Similarly, a core node that is
about to send a Notify_Request to an edge node replaces it with its own
Notify_Request. When a core node receives a Notify message from an edge node and
that Notify message is targeted at the core node, it readdresses it to the
remote core node to which it reports Notifies. When a core node next to an edge
node receives a Notify message and the reporting node is not within the core, it
readdresses it to the report-to node specified in the original Notify_Request
object.

(can we have a name for a core node adjacent to an edge node?)


In section 6, should we have some statement about PathErr with state removal or
would this always be propagated?

Also in section 6, I wonder whether the core should have liberty to use
alarm-free setup and tear-down even if the edge networks do not.  It seems
likely that the edge networks might not be concerned with alarms (possibly being
packet switched), but the core will care.


Let me know if you want text.
Cheers,
Adrian