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Damping Mechanism To Reduce The Status Notification Traffic In Networks With Explicit Path Routing

IP.com Disclosure Number: IPCOM000052105D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 7 page(s) / 141K

Publishing Venue

IBM

Related People

Comer, M: AUTHOR [+3]

Abstract

Computer communication networks employing a subset of fixed routing schemes known as "explicit Path Routing" [1,2,3] need mechanisms to keep track of the status of these routes, i.e., whether they are inoperative, operative, or active. The most frequent reasons for status changes are temporary link and node failures, and operative path activations. For networks of moderate size the status notification employed presently [2,3] seems to be adequate. For large networks consisting of many nodes the status notification traffic thus generated represents a significant additional load for transmission links and processors which can lead to substantial performance degradations or require additional resources.

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Damping Mechanism To Reduce The Status Notification Traffic In Networks With Explicit Path Routing

Computer communication networks employing a subset of fixed routing schemes known as "explicit Path Routing" [1,2,3] need mechanisms to keep track of the status of these routes, i.e., whether they are inoperative, operative, or active. The most frequent reasons for status changes are temporary link and node failures, and operative path activations. For networks of moderate size the status notification employed presently [2,3] seems to be adequate. For large networks consisting of many nodes the status notification traffic thus generated represents a significant additional load for transmission links and processors which can lead to substantial performance degradations or require additional resources.

Described herein is a new and improved method for notifying the end points of explicit routes (ERs) of status changes to ERs, which avoids the shortcomings of known schemes.

The new status notification mechanism which resides in intermediate nodes requires the following set of states describing the status of an ER in order to decide whether status information has to be propagated to neighbor nodes: See Original.

The state diagram represented in Fig. 1 contains these new states together with the appropriate transition rules. Furthermore, it summarizes the proposed new status propagation rules which will be introduced and explained below. On the other hand, Fig. 2 depicts the present mechanism which is based on only two states, and thus does not have enough information to prevent unnecessary propagation of status information.

There are three control messages to carry ER status information which are relevant for the present discussion (also, see Fig. 1) and which may lead to state transitions: See Original.

The key idea of the damping mechanism focusses on the quest when to propagate an ER-status message, provided the new set of states is available for the decision making process.

From the present status notification process the following two requirements are kept pertaining to notification of users and managers of ERs in case these routes become inoperative/operative: 1. Notification of the users that an ER they are using has failed. This allows users to take appropriate recovery action. 2. Notification to ER managers that inoperative ERs have become operative, and therefore are available for use. (ER managers can be conceived as residing in switching nodes and of being responsible for all ERs originating/terminating in a node.) This saves ER managers from having to repeatedly test an inoperative ER to see if it has started to work.

The status notification mechanism described in [2] additionally requires that ER managers be notified when their ER has become inoperative even when the ER manager has not act...