Subject: [GSMP] Protection

From: avri <[email-masked]>
Date: Tue, 1 Jul 2003 18:00:51 +0900

i have seen and worked through a few possible solutions
for the protection requirements,
but i am looking for the one that is the simplest and requires the
fewest changes to the protocol.

i have started making some simplifying assumptions, and i am
not sure to what extent the hold.  So before making any changes
to the spec i am hoping the specialists of protection will let me
know if i am wrong.

(and apologies in advance if i display glaring ignorance.)

1.

1+1 protection is not really that much different in terms of messages
then any other add.  First one creates a branch.  Then, as is done
for  multicast, one adds other branches.  The main
difference is that one would have to designate the appropriate
branches as the protection ones and thus distinguish them from
multicast.

Implicit in this assumption is that dedicated protection branches
terminate on the same port as either the input or output port of the
primary branch since they have a common label (either input or output)

This would still leave issues of deletion, as I assume the protection
link(s) should be deleted at the same time as the primary link.  The
simplest solution is for it to be a requirement that in deleting a 
protected
link, the controller must also include delete the protection branch.

2.

In the non dedicated protection modes one is reserving resources and
notifying the switch that these resources are possibly available
for use as protection/recovery links for designated branches.  In the
case of non dedicated protection, the protection link(s) can be 
associated
with multiple connections.  Assuming this is the case, then i could 
modify
the reservation message to indicate which reservations are for
protection branches and modify the connection messages
to include several reservation ids.

I am making the assumption that it is not necessary in the case of
non-dedicated protection that the branches be on the same ports
as either the input or output label.  This will need to be accounted 
for.

In the case of deletion of a primary branch, I also assume that the
protection will not necessary be  deleted, though it will be 
disassociated
from the branch being deleted.  I am not sure that this needs to be
dealt within the GSMP messaging, though the switch would need to do
the housekeeping.

comments please!

a.

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