Method and system for switch fabric flow control

Details Method and system for switch fabric flow control Method and system for switch fabric flow control

2001-03-19

2003-11-25

Chin, Wellington (Department: 2664)

Multiplex communications

Data flow congestion prevention or control

C370S236000, C370S389000

Reexamination Certificate

active

06654343

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to field of data switching. More specifically, the present invention is directed to controlling flow of packets/cells in a switch.
BACKGROUND
The desire to integrate data, voice, image, video and other traffic over high speed digital trunks has led to the requirement for faster networks including the capability to route more information faster from one node to another node. A switch performs this routing of information. Generally, the switch consists of three logical elements: ports, a switch fabric and a scheduler.
Routing and buffering functions are two major functions performed by a switch fabric. New packets arriving at an ingress are transferred by the scheduler across the switch fabric to an egress. The ingress refers to a side of the switch which receives arriving packets (or incoming traffic). The egress refers to a side of the switch which sends the packets out from the switch.
Most of the switches today are implemented using a centralized crossbar approach.
FIG. 1
is an exemplary illustration of a centralized crossbar switch. The packets arrive at the centralized crossbar switch
100
at multiple ingress ports
105
on the ingress
102
. They are transferred across the switch fabric
110
to multiple egress ports
115
on the egress
104
and then sent out to an output link (not shown). The centralized crossbar switch
100
can transfer packets between multiple ingress port-to-egress port connections simultaneously.
A centralized scheduler controls the transfer of the packets from the ingress ports
105
to the egress ports
115
. Every packet that arrives at the ingress ports
105
has to be registered in the centralized scheduler. Each packet then waits for a decision by the centralized scheduler directing it to be transferred through the switch fabric
110
. With fixed size packets, all the transmissions through the switch fabric
110
are synchronized.
Each packet belongs to a flow, which carries data belonging to an application. A flow may have multiple packets. There may be multiple flows arriving at the ingress ports
105
at the same time. Since the packets in these multiple flows may be transferred to the same egress port, each of these packets waits for its turn in ingress buffers (not shown) in the ingress
102
.
The centralized scheduler examines the packets in the ingress buffers and chooses a set of conflict-free connections among the appropriate ingress ports
105
and egress ports
115
based upon the configuration of the switch fabric
110
. One of the egress ports
115
may receive packets from one or more ingress ports
105
. However, at any one time, the centralized scheduler ensures that each ingress port is connected to at most one egress port, and that each egress port is connected to at most one ingress port.
Each packet transferred across the switch fabric-
110
by the centralized scheduler waits in egress buffers (not shown) in the egress
104
to be selected by the centralized scheduler for transmission out of the switch. The centralized scheduler places the selected packets in the appropriate egress ports
115
to have the packets transmitted out to an output link.
The requirement that every packet has to be registered with the centralized scheduler and that the centralized scheduler serves as a common arbitration point to determine the packets to be sent across the switch fabric
110
, among others, make the centralized cross bar approach very complex.
SUMMARY OF THE INVENTION
A system for controlling flows across a switch fabric is disclosed. In one embodiment, an ingress is coupled with the switch fabric to send flows of data across the switch fabric. Each of the flows of data is associated with a flow identification information and a priority level. An egress is coupled with the switch fabric to receive the flows of data from the ingress. The egress is configured to send one or more flow control messages to the ingress to control a pace that the ingress sends the flows of data to the egress. Each of the flow control messages includes one or more of a flow identification information, an egress space availability information and a new priority level for a flow.


REFERENCES:
patent: 5774453 (1998-06-01), Fukano et al.
patent: 5838922 (1998-11-01), Galand et al.
patent: 5910942 (1999-06-01), Grenot et al.
patent: 5959991 (1999-09-01), Hatono et al.
patent: 6067298 (2000-05-01), Shinohara
patent: 6324165 (2001-11-01), Fan et al.
Nick McKeown, Martin Izzard Adisak Mekkittikul, William Ellersick, Mark.
Horowitz, “The Tiny Tera: A Packet Switch Core”, Dept. of electrical Enginerring & Computer.
Science, Stanford University, Stanford, CA 94305-4070, DSP R&D Center, Corporate Research & Development, Texas Instruments, Incorp., PO Box 655474, MS446, Dallas, TX75265.

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