Switch, scheduler thereof, and switch scheduling method

Details Switch, scheduler thereof, and switch scheduling method Switch, scheduler thereof, and switch scheduling method

2000-03-30

2004-10-26

Kizou, Hassan (Department: 2662)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S235000, C370S413000, C370S389000

Reexamination Certificate

active

06810038

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network switch such as a router or switch, etc., that performs data transfer in a network (in the following description, these apparatuses are referred to by the generic term “switch”), and more particularly relates to a switch that performs switch scheduling in accordance with priority levels set in the data, together with the associated scheduler and switch scheduling method.
2. Description of the Prior Art
Previously, data traffic on the Internet has been characterized as of “best effort” type, and traffic Quality of Service (QoS) has not been implemented with respect to zones, delays, fluctuation s, etc. When a switch that transfers IP packets received a packet, it has only performed packet transfer with the QoS available at the time the packet was received, and QoS has not been assured.
However, the emergence of protocols such as RSVP (Reservation Protocol) and DiffServ (Differentiated Service) has made it possible for traffic QoS to be assured as a protocol, even on the Internet.
With switches, also, technology has been proposed for implementing QoS assurance with traffic classified by QoS. An example of this kind of prior art is the switch shown in Japanese Patent Laid-Open No. 10-200550.
Meanwhile, functions provided by VoIP (Voice over IP), etc., have made it possible to accommodate telephonic speech on the Internet, and there have been moves by telephone companies to implement telephone networks by means of the Internet. As a result, QoS assurance requirements for the Internet have become even more stringent in recent years.
FIG. 14
shows the configuration of a conventional switch, and
FIG. 15
shows the switching operation by the switch in
FIG. 14
in its flowchart. With reference now to
FIG. 14
, the switch comprises a plurality of input ports
110
a
to
110
b
that input data, a plurality of output ports
140
a
to
140
b
that output data, a switching execution block
130
that switches data input from the input ports
110
a
to
110
b
and transmits it to the output ports
140
a
to
140
b
, and a scheduler
120
that controls switching by the switching execution block
130
. The input ports
110
a
to
110
b
each comprise queues
111
provided for each output port.
With reference now to the flowchart in
FIG. 15
, first, when an input port
110
a
to
110
b
receives data destined for one of the output ports
140
a
to
140
b
, that data is queued in a per-output-port queue
111
(step
1501
). Next, in order to request switch
130
connection, the input port
110
a
to
110
b
sends the scheduler
120
a request for connection to the desired output port (step
1502
).
When the scheduler
120
accepts connection requests from input ports
110
a
to
110
b
, it performs connection destination allocation in such a way as to avoid mutual collision between connections from individual input ports
110
a
to
110
b
to output ports
140
a
to
140
b
(step
1503
). Then, it sets the switch
130
according to the allocation (step
1504
), and returns Grant signals to the input ports
110
a
to
110
b
indicating the respective connection destination output ports
140
a
to
140
b
(step
1505
).
The individual input port
110
a
to
10
b
transmits to the switch
130
the data destined for the connection destination output port reported by the Grant signal (step
1506
). Then, the switch
130
performs switching in accordance with the setting by the scheduler
120
, and transmits the accepted data to the individual output port
140
a
to
140
b
(step
1507
).
However, in switch scheduling by means of the prior art described above, uniform scheduling is performed that takes no account of the quality, priority, etc., of the data being switched. Consequently, when performing transfer via the Internet of traffic, such as telephonic speech, with stringent requirements in terms of delay characteristics, or when traffic using a number of protocols with differing quality and characteristics is handled by a single switch, it is not possible to achieve switching in accordance with traffic quality.
In Japanese Patent Laid-Open No. 8-56230, a switching system is shown that implements switch scheduling according to priority. In the switching system shown in this Patent Publication, traffic of all priorities is simultaneously scheduled by a single scheduler. That is to say, as shown in
FIG. 16
, the scheduler
1610
has, for each cell entry, a tag register
1620
that has tags showing cell priority, and a comparator
1630
that compares the values of the priorities held in the tag register
1620
, and performs scheduling by comparing the cell priorities sequentially, one by one. Therefore, the scheduler
1610
must perform the task of scheduling by judging all priorities within one cell time interval (one time slot). Moreover, a special scheduling algorithm must be provided in order to satisfy this condition.
BRIEF SUMMARY OF THE INVENTION
OBJECT OF THE INVENTION
Since, in conventional switch scheduling, uniform scheduling is performed that takes no account of the quality, priority, etc., of the data being switched, as described above, a defect of conventional switch scheduling is that it may not be possible to implement switching in accordance with traffic quality.
Moreover, a shortcoming of the switching system described in Japanese Patent Laid-Open No. 8-56230 is that the configuration of the apparatus is made complex by the need to perform the task of scheduling by judging all priorities within one cell time interval (one time slot). A further shortcoming of this switching system is that flexible setting changes cannot be made because of the need for a special scheduling algorithm.
The present invention has as an objective the provision of a switch, and its associated scheduler and switch scheduling method, that solve the above mentioned defects in the conventional system, and implement flexible switch scheduling in accordance with priority levels set in the data, by means of a simple apparatus configuration.
Further, the present invention has as an objective the provision of a switch, and its associated scheduler and switch scheduling method, that can easily be introduced into a network system by implementing switch scheduling that includes priority control using, without modification, the conventional means of switch scheduling (algorithm, etc.) that does not include priority control.
SUMMARY OF THE INVENTION
An aspect of the present invention that attains the above mentioned object comprises a plurality of input ports that input transfer data and a plurality of output ports that output transfer data; means for executing switching that switches transfer data that is input from said input ports and transmits it to said output ports; and a scheduler that controls switching by said means for executing switching in response to connection requests for said transfer data from said input ports; wherein said scheduler, in a switch that is provided in a network and performs IP packet transfer, comprises distribution means that inputs said transfer data from said input ports and distributes connection requests for said transfer data in accordance with priority levels set in said transfer data that is input; first means for switch connection allocation that performs switch connection allocation corresponding to connection requests for said transfer data with a high priority level from among the connection requests distributed by said distribution means; second means for switch connection allocation that performs switch connection allocation corresponding to connection requests for said transfer data with a low priority level from among the connection requests distributed by said distribution means; combination means that combines the results of switch connection allocation by said first means for switch connection allocation and said second means for switch connection allocation; and means for permitting switch connection that, on the basis of the result of switch connection allocation comb

Affiliated with

Also associated with

Rating

Switch, scheduler thereof, and switch scheduling method does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Switch, scheduler thereof, and switch scheduling method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switch, scheduler thereof, and switch scheduling method will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3285328