Information Technology Reference
In-Depth Information
o
Path Protection spends longer time for service restoration compared to Link-based
Shared protection.
o
Path-based Shared protection can immensely save resource protection capacity as
compared with Link-based Shared protection and Path-based Dedicated Protection.
However, the restoration time is longer and increases computations.
o
Using p-cycle is much more capacity efficient than using dedicated path protection.
o
Link-based Shared protection spends longer time for service restoration compared to
Link-based Dedicated Protection.
o
Link-based Dedicated Protection has more reserved capacity than Link-based Shared
protection.
o
Usually Virtual Link-based Shared Protection has a less capacity comparing to
Virtual Link-based Dedicated Protection.
o
Virtual Link-based Shared Protection has longer restoration time compared to Virtual
Link-based Dedicated Protection.
o
Segment Protection has a faster recovery in proportion to Path-based Shared
Protection because the backup segments usually are shorter than backup paths used
in Path Protection.
o
The 1:N protection is more efficient in terms of protection resources as compared to
1+1 protection, but it still needs time to detect failure and to reroute signals.
o
The 1+N is fast and inexpensive recovery from failures by providing two copies of
the same signal on two disjoint paths.
5.2. Comparison among Protection Techniques Supporting Unicast Traffic
In this section, we compare the complexity and blocking probability of protection
schemes that can support unicast traffic with each other. For all illustrated algorithms, the
information of blocking probabilities has been obtained from their relevant references
([14,22-30]). Table 3 shows the complexity of the algorithms, where
V
is the set of network
nodes, and
D
is the set of destination nodes. Moreover,
K
is the number of feasible cycles to
every possible destination,
T
is the time to derive a backup segment,
N
is the number of
network nodes,
W
is the number of wavelengths,
L
is the set of links, and
n
is the number of
nodes of the working paths. Moreover,
K
is the number of cycle in the FT-ABR algorithm
and
k
is the number of candidate working and candidate backup paths. In the following, when
information is not available for a parameter, we use term Not Available (
NA
).
According to Table 4, we can see that for
W
=16, TS has a lower blocking probability than
RSSP at high load, but blocking probability of RSSP is low at light load. However, TS has
lower complexity than RSSP (see Table 3). Moreover, at
W
=8, LSA has the lower blocking
probability than FT-ABR and HCSPP.
5.3. Comparison among Protection Techniques Supporting Multicast Traffic
In this section, we compare the protection schemes that support multicast traffic with
each other. In multicast protection schemes, the complexity and blocking probability are
important parameters. For all illustrated algorithms, the information of blocking probabilities
