??? SRS-length field: The field contains the length of one DS. However, SRS-length
combined with FCRB provides sufficient information about the DB??™s length and segmentation.
To avoid congestion in OBS control-channel, SRS-length should comply
with a minimum length (Detti et al., 2002), which is the minimum permitted data burst
length transmitted over the optical links. The SRS-length may vary from one DB to
another.
??? Other-Info fields: The rest of the fields may contain routing information (e.g., burst
destination address), offset time, and so forth.
By adopting SRS dropping policy, which will be described in the following subsection, if
a contention is anticipated in the core-nodes, the resources allocation process will not be
aborted (i.e., BCP is dropped and subsequently the corresponding DB is entirely discarded).
Conversely, the FCRB field in the corresponding BCP is updated according to the resources
that the core-node can provide (or free up). Hence, only the overlapping segments are dropped
at the arrival time, allowing part of the DB to be transmitted (i.e., the data length that can be
handled by the node at the arrival time) as shown in Figure 5. Since the BCPs are updated
before forwarding them to the downstream nodes, to reflect the new DBs??™ length, the need
for trailing messages is eliminated, and the contention is resolved at the BCPs level rather
than at the DBs level.
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