Optimum Arrangement of Reliable Label-Switched Paths in MPLS Over Optical Networks |
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Authors: | Nagao Ogino Hideaki Tanaka |
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Affiliation: | (1) KDDI R&D Laboratories Inc., 2-1-15 Ohara, Kamifukuoka-shi, Saitama 356-8502, Japan |
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Abstract: | In MPLS (Multi-Protocol Label Switching) over optical networks, both the optical level and the MPLS level fault recovery can
be considered. Generally, a more flexible path arrangement can be realized by the MPLS level recovery, while fast recovery
can be achieved by the optical level recovery. When the optical level recovery is adopted, only normal traffic is carried
through the working lightpaths and only recovered traffic is carried through the backup lightpaths. In contrast, the working
LSPs (Label-Switched Paths) and the backup LSPs corresponding to other working LSPs can be accommodated into an identical
lightpath when the MPLS level recovery is adopted. By such sophisticated accommodation of LSPs into the lightpaths, lightpath
bandwidth can be utilized efficiently under the condition that the bandwidth utilization is restricted to attain the given
objective of transfer quality for the MPLS packets in the normal state and unrestricted in a short time a failure occurs somewhere
in the network. This paper proposes a simple mathematical programming model to obtain the optimum arrangement of the working
and backup LSPs assuming the MPLS level recovery and a practical LSPs provisioning mode. By comparing the minimized network
cost obtained from the optimum arrangement of the working and backup LSPs with the network cost resulting from the optical
level recovery, this paper quantitatively evaluates the effectiveness of such bandwidth utilization improvement obtained from
the MPLS level recovery and reveals that the MPLS level recovery can actually reduce the network cost due to its flexible
arrangement of LSPs on the lightpaths. |
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Keywords: | MPLS over optical networks MPLS level fault recovery Arrangement of working and backup LSPs Network cost Mathematical programming model |
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