EP0254047A2
Expired / Lapsed
EP
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Packet length traffic control in a local area network
Assignee: International Business Machines Corp
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Filing: 1987-06-23
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Granted: —
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Expires: 2007-06-23
Abstract
Abstract A distributed control apparatus and method is disclosed to maintain the network stability in a packet switching local area network under changing traffic load conditions, by adaptively controlling the size of the packets transmitted by each node. The invention monitors the present information flow rate in the network and computes an average packet length which it then uses to adjust the size of the variable length data field in each message frame. In this manner, network flow control can be achieved without forcing data terminals connected to the nodes of the network to adjust their speed. The invention is applicable to a wide variety of local area network protocols for both ring and bus architectures.
Inventors
- 👤 Herman Blasbalg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 17:40
CPC Classifications
H; H04; H04L; H04L47/00; H04L47/10; H04L47/36; H04L47/11; H04L47/13
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
259 words
In a communications network having a plurality of nodes connected to a multiple access communications medium, with each node executing an access method to obtain exclusive access to the medium after which the node gaining access transmits a packet of information over the medium, an adaptive packet length apparatus for minimizing the average delay for each node gaining access to the medium, comprising: storage means (72, Fig.4 ) for storing program instructions representing the functional relationship between the packet length (Lp) for said packets and the information flow rate (R) in said medium, corresponding to the minimum value of the average delay (T) for a node to gain access to said medium; measurement means (52) coupled to said medium for measuring the average information flow rate in said medium; buffer means (68) at each node coupled to a source (26, 28) of information to be transmitted and coupled to said medium (20), for temporarily storing a block of said information from said source prior to transmission over said medium; computing means (70) connected to said storage means, to said measurement means and to said buffer means, for receiving a measured value of said average information flow rate from said measurement means, executing said program instructions from said storage means to operate on said measured value to compute a resultant packet length value, and accessing a sub-block of said block of information in said buffer means, having a length approximate to said resultant packet length value; said buffer means outputting said accessed sub-block of information for transmission over said medium.
Claim 2
Dependent Claim
259 words
In a communications network having a plurality of nodes connected to a multiple access communications medium, with each node executing an access method to obtain exclusive access to the medium after which the node gaining access transmits a packet of information over the medium, an adaptive packet length apparatus for minimizing the average delay for each node gaining access to the medium, comprising: storage means (72, Fig.4 ) for storing program instructions representing the functional relationship between the packet length (Lp) for said packets and the information flow rate (R) in said medium, corresponding to the minimum value of the average delay (T) for a node to gain access to said medium; measurement means (52) coupled to said medium for measuring the average information flow rate in said medium; buffer means (68) at each node coupled to a source (26, 28) of information to be transmitted and coupled to said medium (20), for temporarily storing a block of said information from said source prior to transmission over said medium; computing means (70) connected to said storage means, to said measurement means and to said buffer means, for receiving a measured value of said average information flow rate from said measurement means, executing said program instructions from said storage means to operate on said measured value to compute a resultant packet length value, and accessing a sub-block of said block of information in said buffer means, having a length approximate to said resultant packet length value; said buffer means outputting said accessed sub-block of information for transmission over said medium.
Claim 3
Dependent Claim
42 words
The apparatus of claim 1, wherein each node of said network includes said storage means (72), said measurement means (52) and said computing means (70), for distributed adaptive control of the lengths of the packets of information transmitted from each respective node.
Claim 4
Dependent Claim
31 words
The apparatus of claim 1, wherein the form of said functional relationship stored in said storage means (72) is an arithmetic expression relating packet length (Lp) and information flow rate (R).
Claim 5
Dependent Claim
31 words
The apparatus of claim 1, wherein the form of said functional relationship stored in said storage means (72) is a table of corresponding values relating packet length and information flow rate.
Claim 6
Dependent Claim
51 words
The apparatus of claim 1, wherein said functional relationship stored in said storage means (72) relates increases in the packet length (Lp) to increases in the measured value (R) of the information flow rate, in order to minimize the average delay (T) for a node to gain access to said medium.
Claim 7
Dependent Claim
20 words
The apparatus of claim 1, wherein said network is a carrier sense multiple access with collision detection local area network.
Claim 8
Dependent Claim
17 words
The apparatus of claim 1, wherein said network is a token ring multiple access local area network.
Claim 9
Dependent Claim
98 words
In a local area network, a method to optimize the waiting time (T) required for a particular node in order to gain access to the network, comprising the steps of: sensing at a particular node on the local area network, the traffic load (R) on the network; comparing said sensed traffic load to a reference load value; adjusting the packet length (Lp) for messages originating from said particular node, in response to said comparison, so as to achieve a packet length which gives said particular node a minimum waiting time in order to gain access to the network.
Claim 10
Dependent Claim
98 words
In a local area network, a method to optimize the waiting time (T) required for a particular node in order to gain access to the network, comprising the steps of: sensing at a particular node on the local area network, the traffic load (R) on the network; comparing said sensed traffic load to a reference load value; adjusting the packet length (Lp) for messages originating from said particular node, in response to said comparison, so as to achieve a packet length which gives said particular node a minimum waiting time in order to gain access to the network.
Claim 11
Dependent Claim
199 words
In a communications network having a plurality of nodes connected to a multiple access communications medium, with each node executing an access method to obtain exclusive access to the medium after which the node gaining access transmits a packet of information over the medium, the adaptive packet length control method of Claim 8 for minimizing the average delay for each node gaining access to the medium, comprising the steps of: storing the relationship between the packet length (Lp) for said packets and the information flow rate (R) in said medium, corresponding to the minimum value of the average delay for a node to gain access to said medium; measuring the average information flow rate in said medium; buffering a block of said information received from an information source, prior to transmission thereof over said medium; computing a resultant packet length value from said measured information flow rate; accessing a sub-block of said block of buffered information, having a length approximate to said resultant packet length value; outputting said accessed sub-block of information for transmission over said medium; repeating said steps of accessing and transmitting a sub-block until said entire buffered block of information has been transmitted over said medium.
Claim 12
Dependent Claim
37 words
The method of Claim 8 comprising the steps of: comparing the differential load value obtained in that comparison step to an adaptive threshold value; adjusting the packet length only is the differential value exceeds said threshold value.
References Cited (Backward Citations)
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