In-band message synchronization for distributed shared memory packet switch

Abstract

A packet switching system comprising a plurality of ingress control units (10), a plurality of egress control units (12), and a switch fabric (14), including a plurality of packet buffer units (16), which may concurrently transmit notification message to a particular egress control unit (12) in response to packets received from the plurality of ingress control units (10). Each PBU (16) includes a notification queue (64) associated with the egress control unit (12) for storing notifications generated by the PBU (16). Notifications in the notification queues (64) are ordered according to the ingress control units (10) triggering the notifications and retrieved via a time-driven pointer that is initialized to a different start entry position for the notification queues (64).

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of US Provisional Patent Application No. 60 / 306,197, filed July 17, 2001, the contents of which are hereby incorporated by reference. technical field [0003] The present application relates generally to packet switching systems, and more particularly to synchronizing notification messages sent to an output scheduler within a distributed shared memory packet switch. Background technique [0004] The switching fabric within the data communications switch facilitates the transfer of data packets received from input ports to output ports for forwarding the packets to their destinations. The switch fabric may be implemented as a crossbar switch, a cell switch, or a shared memory packet switch. One advantage of a shared memory packet switch compared to other kinds of switching fabrics is its robustness under high traffic loads. Shared memory packet switches generally provide lower pack...

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Problems solved by technology

Thus, shared memory packet switches typically lack scalability at data rates exceeding 100Gbit / s

[0006] A U.S. patent application entitled "Distributed Shared Memory Packet Switch" filed May 15, 2002, assigned to the assignee of the present application, the content of which is incorporated by reference, proposes a packet switch utilizing distributed shared memory A solution to overcome the lack of scalability of shared-memory packet switches

[0008] With the above solution, a situation may arise that at a particular instant, the output control unit receives multiple notifications sent by multiple packet buffer units via their corresponding output serial links, resulting in the Sudden overload of notifications handled by unit

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