Region Protection/Restoration Scheme in Survivable Networks - Computer Network Security - page 442

Region Protection/Restoration Scheme
in Survivable Networks
Wojciech Molisz and Jacek Rak
Gdansk University of Technology, ul. Narutowicza 11/12,
80-952 Gdansk, Poland
[e-mail], [e-mail]
Abstract. In this paper we propose the novel concept of a region protec-
tion/restoration, where one backup path protects a certain region of an active
path. We show that using the region protection/restoration we can keep both
restoration times and network resource utilization ratio at the reasonable level.
Since the optimization problem of finding working and backup paths is
NP-complete, we developed the heuristic algorithm. We show that in the worst
case our algorithm gave network resource utilization ratio only about 3.9 per-
cent higher compared to the optimal one returned by the CPLEX program. Re-
sults of the U.S. Long-Distance Network modeling show that region protection
gives a good compromise between path and link protection.
1 Introduction
We define survivability as the capability of a networked information system to fulfill
its mission, in the presence of attacks, failures, or intrusions. Protection and restora-
tion [4], [5] have emerged as the two main techniques for fault management in sur-
vivable networks. We distinguish two basic approaches: path protection/restoration or
link protection/restoration against a single link or a single node failure (damage). Any
path/link protection can be dedicated or shared assuming that backup paths are link-
or node-disjoint with respective active paths [3], [4], [5].
In this paper we study various protection techniques and show that shorter restora-
tion times imply greater network resource utilization ratio and vice versa. To find
a compromise, we propose a novel approach, which we call region protec-
tion/restoration . The key idea of our region protection is to protect a certain region of
an active path with help of one backup path. This concept offers a good trade-off
between restoration time and resource utilization ratio.
We call an individually protected area, the area of an active path that is protected
by a single backup path. In the path protection model (with backup paths being
link-disjoint 1 or node-disjoint 2 with active paths), the whole active path determines
the individually protected area. On the contrary, a single link of an active path is an
1 By link-disjoint we mean that the backup path for a connection has no links in common with
the primary path for that connection.
2 By node-disjoint we mean that the backup path for a connection has no nodes in common
with the primary path for that connection, except the source and destination nodes.