EP0632621A2
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EP
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Interpacket gap management for ethernet
Assignee: Cabletron Systems Inc
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Filing: 1994-06-28
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Granted: —
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Expires: 2014-06-28
Abstract
Abstract A technique for modifying the IEEE 802.3 standard for selecting transmit-to-transmit interpacket gap (IPG) intervals in a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network, in the event that a node has captured the network communication channel. If there is a small number of active nodes on the network, one node may capture the channel and the standard backoff algorithm makes it increasingly unlikely for another node to transmit. The new technique provides for less aggressive, i.e. longer, interpacket gap (IPG) intervals to be used by a node that has captured the channel, thereby increasing the likelihood that another node will gain access.
Inventors
- 👤 Henry Sho-Che Yang
- 👤 Kadangode Kl. Ramakrishnan
- 👤 William R. Hawe
- 👤 Anthony G Lauck
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 10:56
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/407; H04L12/413
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
For use in a node of a network employing a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol for channel access wherein there is a plurality of nodes, and wherein a plurality of data packets is transmitted through a network channel, a method for improving fairness of access to a channel, comprising the steps of: sensing whether a predetermined node has captured the channel; and if said predetermined node has not captured the channel, observing a prescribed transmit-to-transmit interpacket gap IPG, after completing a transmission and before any attempt at transmitting or retransmitting a packet; after sensing capture of the channel, selecting an increased transmit-to transmit interpacket gap interval that must be observed before any attempt at transmitting or retransmitting a packet; whereby the selected increased IPG gives a node that has not captured the channel is given an increased likelihood of transmitting before said predetermined node, and overcoming capture of the channel.
Claim 2
Dependent Claim
78 words
A method as defined in claim 1, wherein the step of sensing when said predetermined node has captured the channel includes: sensing when a first packet has been successfully transmitted by said predetermined node; after transmitting the first packet, and without any intervening successful transmission by another node, winning access to the channel again following a collision; and sensing when a second packet has been successfully transmitted by said predetermined node after winning access in the prior step.
Claim 3
Dependent Claim
60 words
A method as defined in claim 1, wherein: the method further comprises the step of detecting a collision between a transmission from said predetermined node and a transmission from another node; and wherein the step of selecting an increased transmit-to-transmit IPG interval includes selecting a progressively larger interval after each collision experienced following a successful transmission by said predetermined node.
Claim 4
Dependent Claim
59 words
A method as defined in claim 3, wherein: the step of selecting a progressively larger IPG interval includes increasing the IPG interval in equal steps until a maximum value equal to one slot time is reached, where the slot time is the time needed to propagate a signal from one end of the network to the other and back.
Claim 5
Dependent Claim
32 words
A method as defined in claim 1, and further comprising the step of: sensing when another node has successfully transmitted a packet and reverting to use of a standard transmit-to-transmit IPG interval.
Claim 6
Dependent Claim
145 words
For use in a node of a network employing a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol for channel access, apparatus for improving fairness of access to a channel, comprising: means for sensing when a predetermined node has captured the channel for successive transmissions by said predetermined node; means operative if said predetermined node has not captured the channel, for selecting a presesibed transmit-to-transmit interpacket gap (IPG) interval after completing a transmission and before any attempt at transmitting or retransmitting a packer; and means operative after sensing capture of the channel, for selecting an increased transmit-to-transmit interpacket gap (IPG) interval that must be observed before any attempt at transmitting or retransmitting a packet; whereby an increased IPG gives a node that has not captured the channel is given an increased likelihood of transmitting before said predetermined node and overcoming capture of the channel.
Claim 7
Dependent Claim
91 words
Apparatus as defined in claim 6, wherein the means for sensing when said predetermined node has captured the channel includes: means for sensing when a first packet has been successfully transmitted by said predetermined node; means operative after transmitting the first packet, and without any intervening successful transmission by another node, for sensing when said predetermined node wins access to the channel again following a collision; and means for sensing when a second packet has been successfully transmitted by said predetermined node after winning access to the channel following the collision.
Claim 8
Dependent Claim
63 words
Apparatus as defined in claim 6, wherein: the apparatus further comprises means for detecting a collision between a transmission from said predetermined node and a transmission from another node, wherein; the means for selecting an increased transmit-to-transmit IPG interval includes means for selecting a progressively larger interval than one previously selected after each collision experienced following a successful transmission by said predetermined node.
Claim 9
Dependent Claim
60 words
Apparatus as defined in claim 8, wherein: the means for selecting a progressively larger IPG interval includes means for increasing the IPG interval in equal steps until a maximum value equal to one slot time is reached, where the slot time is the time needed to propagate a signal from one end of the network to the other and back.
Claim 10
Dependent Claim
39 words
Apparatus as defined in claim 6, and further comprising: means operable after channel capture, for sensing when another node has successfully transmitted a packet and reverting in this former channel-capturing node to use of the prescribed transmit-to-transmit IPG interval.
References Cited (Backward Citations)
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