Simon Tembo^*, Ken-ichi Yukimatsu, Shohei Kamamura, Takashi Miyamura, Kohei Shiomoto, Atsushi Hiramatsu

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Department of Computer Science and Engineering, Akita University, Akita City, Japan.
NTT Network Service Systems Laboratories, NTT Corporation, Tokyo, Japan.
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Abstract: Shutting down a link for the purposes of a scheduled routine maintenance does cause the forwarding path to change. If these changes are not done in a required order will cause not only transient micro loops but also an overload in some links. Currently, some ISP operators use a graceful link shutdown procedure by first setting up the Interior Gateway Protocol (IGP) link metric to MAX_METRIC -1 and then shutdown the link. In this paper, we present a Pythagorean Triple Metric Sequence as a method to use to shutdown a link during such network operations. Conducting a link shutdown of any desired link for maintenance purpose is a very delicate duty that requires extreme care to prevent transient loops during such topological changes. We thus wish to demonstrate that there exists a Pythagorean Triple Metric Sequence for any given link that can be used to shutdown a link during the routine maintenance by ISPs.

Keywords: MAX_METRIC; Link Shutdown; Pythagorean Triple Metric Sequence; Target Metric; Forwarding Path; Planned Failures

Cite this paper: S. Tembo, K. Yukimatsu, S. Kamamura, T. Miyamura, K. Shiomoto and A. Hiramatsu, "Usage of Pythagorean Triple Sequence in OSPF," Communications and Network, Vol. 4 No. 1, 2012, pp. 73-82. doi: 10.4236/cn.2012.41010.

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