Method and apparatus for processing packets in a routing switch

(54) METHOD AND APPARATUS FOR

PROCESSING PACKETS IN A ROUTING
SWITCH

(75) Inventor: Alwarkurichi Padmana Nagaraj,

Garland, TX (US)

(73) Assignee: Nortel Networks Limited, St. Laurent (CA)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/293,464

(22) Filed: Apr. 15, 1999

(51) Int. CI.7 H04L 12/56; H04L 12/26

(52) U.S. CI 370/389; 370/252; 370/413;

370/395.31; 709/242

(58) Field of Search 370/356, 360,

370/363, 368, 371, 374, 378, 381, 389, 390, 392, 397, 398, 399, 395.21, 395.3, 395.32, 252, 395.31, 254, 411-419, 351-355, 400-402; 709/238, 242, 244; 707/509, 1, 8; 359/114, 117, 118; 398/42, 58, 49,

51

(56) References Cited

U.S. PATENT DOCUMENTS

4,692,917 A * 9/1987 Fujioka 370/392

5,249,178 A * 9/1993 Kurano et al 370/392

5.265,092 A * 11/1993 Soloway et al 370/254

5,416,769 A * 5/1995 Karol 370/414

5,513,172 A * 4/1996 Shikama et al 370/412

5,535,197 A * 7/1996 Cotton 370/414

5.754,790 A * 5/1998 Fiance et al 709/242

5,781,549 A * 7/1998 Dai 370/398

5,784,367 A * 7/1998 Sannino 370/392

5,802,316 A * 9/1998 Ito et al 370/351

5.848,059 A * 12/1998 Yamamoto 370/420

5,917,805 A * 6/1999 Manning et al 370/414

5,987,008 A * 11/1999 Simpson et al 370/418

6,069,895 A * 5/2000 Ayandeh 370/389

6,073,248 A * 6/2000 Doshi et al 359/118

6,111,673 A * 8/2000 Chang et al 370/392

* cited by examiner

Primary Examiner—Steven Nguyen

(57) ABSTRACT

A method, apparatus, and instructions for processing packets within a routing switch uses a multiprocessor architecture. The routing switch includes a switch fabric, a Routing Table Processing Unit, at least one packet buffer for queuing incoming and outgoing packets, at least one Packet Processing Unit, and a shared memory for storing a routing table. A Packet Processing Unit retrieves packets from a packet buffer memory, which may be a shared memory accessible to more than one of the Packet Processing Units depending upon the internal configuration of the components. The Packet Processing Unit categorizes the packets into routing information packets and data packets. The Packet Processing Unit forwards a routing information packet to a Routing Table Processing Unit and processes any other data packet by retrieving forwarding information from a routing table, updating the packet with the retrieved forwarding information, and forwarding the updated packet using a switch fabric connected to the Packet Processing Unit. A locking mechanism within the routing table memory provides synchronization between the activities of the various processing units. In response to receiving a routing information packet, the Routing Table Processing Unit locks a portion of the routing table, updates the locked portion of the routing table with information from the routing table information packet, and then unlocks the locked portion of the routing table. The Packet Processing Unit waits for a necessary portion of the routing table to be unlocked before retrieving any forwarding information. If more than one packet buffer memory is employed, the routing switch may be configured to support a wavelength division multiplexed (WDM) enabled network such that each input/output interface receives packets over a particular wavelength and queues the packets within separate packet buffers.

21 Claims, 6 Drawing Sheets