domain partitions and routing information

[[e-mail]]

hi woody,

your idea of an annihilating routing information message issued by the
previous domain component representative is a fine one.  however, you
should carefully weigh the advantages and disadvantages before
automatically implementing it.  the advantage is that it quickly
removes old routing information messages, about a previously
partitioned domain X, remaining in the routing information database
after the partition has healed.  this reduces the storage requirements
for routing information and slightly reduces the computational cost of
generating routes that include domain X.  however, the disadvantage is
the communications cost of flooding the annihilating routing
information message to all domains.

without the annihilating routing information message, the old routing
information messages about domain X will not be removed from the
routing information database until they expire.  however, in the mean
time, the route server can use these routing information messages to
generate routes.  when setting up paths for domain components that no
longer exist, a policy gateway in X, that receives a setup message
indicating such a domain components, simply checks that the policy
gateway labelling the extinct component is reachable from itself.  if
so, the path can be set up properly.

thus, waiting for routing information messages, about old domain
components, to expire rather than annihilating them right away is
not necessarily a bad thing.  if route server memory is scarce,
i would recommend the annihilation message.  if not, i would be
tempted to forego it.

m