[54] APPARATUS AND METHOD FOR MAINTAINING FORWARDING INFORMATION IN A BRIDGE OR ROUTER USING MULTIPLE FREE QUEUES HAVING ASSOCIATED FREE SPACE SIZES
[75] Inventors: Martin Edward Griesmer, Arlington;
Parayath Gopal Krishnakumar, West
Newton; David Benson, Acton, all of
Mass.
[73] Assignee: Digital Equipment Corporation,
Maynard, Mass.
[21] Appl. No.: 965,121
[22] Filed: Oct 22,1992
[51] Int CI.6 G06F 15/16
[52] U.S. CI 395/200.17; 395/200.01;
370/241
[58] Field of Search 395/250, 200,
395/200.17, 200.01; 370/95.13
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OTHER PUBLICATIONS
Concepts in data structures and software development by Schneider et al., West publishing company, pp. 134-135, 141-144.
The C programming language by Kernishan et al.. Prentice Hall publication, pp. 185-189.
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Primary Examiner—Parshotam S. Lall
Assistant Examiner—Zarni Maung
Attorney, Agent, or Firm—David A. Dagg; Gary E. Ross;
Arthur W. Fisher
[57] ABSTRACT
A forwarding information management system for a bridge or router is disclosed, including a method and apparatus for maintaining forwarding entries within a forwarding table. The forwarding table is allocated into forwarding entries, and the forwarding entries organized into forwarding entry sets. A set of free queues is used to manage the free space segments in the forwarding table that are not allocated into forwarding entries. Each free queue maintains pointers to free space segments of a particular size. A forwarding entry adding process creates a new forwarding entry set including a new forwarding entry, selects a non-empty free queue for free space segments large enough to hold the new forwarding entry set, and writes the new forwarding entry set one of the free space segments. Also included in the system are a forwarding entry deleting process, a learning process providing input for the forwarding entry adding process, and an aging process providing input for the forwarding entry deleting process. In an example embodiment, a hash table is used to locate the forwarding entry sets in the forwarding table. In a preferred embodiment, forwarding entries within the forwarding entry sets are organized into balanced binary trees.
11 Claims, 11 Drawing Sheets
