US5771235A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scalable CSMA/CD repeater
Assignee: HP Inc
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Filing: 1996-05-01
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Granted: 1998-06-23
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Expires: 2016-05-01
Abstract
Abstract A scalable CSMA/CD repeater is based on polling and collision resolution logic, and slot time and interframe gap negotiation logic controlled by the repeater itself. The repeater based polling and collision resolution provides central control of the backoff and retry algorithm of each connected MAC unit. Thus, the MAC unit does not rely on random backoff mechanisms that significantly degrade performance of prior art systems. Furthermore, the retry by a MAC unit after a collision is managed by commands received from the collision resolution logic in the repeater. The repeater based collision resolution logic ensures that all ports involved in a collision have a fair opportunity to forward a packet without being blocked before enabling all the ports in the network to freely compete again. Furthermore, the negotiation of slot time and interframe gap allows for tight control of delay parameters in the network which are involved in collision resolution and scaling of the technology with increasing MAC unit processing speeds.
Inventors
- 👤 Wen-Tsung Tang
- 👤 W. Paul Sherer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:40
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/403; H04L12/407; H04L12/413
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
112 words
A network device, comprising: a plurality of ports; a repeater unit including logic coupled to the plurality of ports which monitors activity on the plurality of ports i) to transmit a packet received without collision on one port to all other enabled ports in the plurality of ports, and ii) to detect a collision between packets received on a set of ports in the plurality of ports, to identify the ports in the set of ports, and to issue commands to end stations coupled to ports in the set of ports to resolve the collision, the commands indicating to the ports in the set of ports to retry sending of a packet.
Claim 2
Dependent Claim
112 words
A network device, comprising: a plurality of ports; a repeater unit including logic coupled to the plurality of ports which monitors activity on the plurality of ports i) to transmit a packet received without collision on one port to all other enabled ports in the plurality of ports, and ii) to detect a collision between packets received on a set of ports in the plurality of ports, to identify the ports in the set of ports, and to issue commands to end stations coupled to ports in the set of ports to resolve the collision, the commands indicating to the ports in the set of ports to retry sending of a packet.
Claim 3
Dependent Claim
47 words
The network device of claim 1, including: delay parameter negotiation logic, coupled to the repeater unit and the plurality of ports, which communicates with end stations coupled to the plurality of ports to determine delay parameters for use by the repeater unit to detect and resolve collisions.
Claim 4
Dependent Claim
47 words
The network device of claim 1, wherein the repeater unit includes logic to jam the plurality of ports in response to detection of a collision by transmitting jam packets to ports in the plurality of ports, and the commands comprise a control field in the jam packets.
Claim 5
Dependent Claim
25 words
The network device of claim 3, wherein the control field comprises an end of frame control field which carries a command to the end station.
Claim 6
Dependent Claim
69 words
The network device of claim 3, wherein the jam packet has a length as long as a longer of a time from detection of a collision to a time that all ports are quiet or a slot time defined as a delay parameter long enough to allow for a round trip transmission of a packet from a port in the plurality of ports to an end station and back.
Claim 7
Dependent Claim
53 words
The network device of claim 1, wherein the plurality of ports comprise half-duplex ports, and the repeater unit includes logic to jam the plurality of ports in response to detection of a collision by transmitting jam packets to the plurality of ports, and the commands comprise a control field in the jam packets.
Claim 8
Dependent Claim
78 words
The network device of claim 6, wherein the control field comprises an end of frame control field which carries a clear-to-send command to one end station coupled to the set of ports, and a backoff command to other ports in the plurality of ports, so that the one end station receiving the clear-to-send command in the end of frame control field of the jam packet has an opportunity to send a packet without collision after the jam packet.
Claim 9
Dependent Claim
33 words
The network device of claim 1, including a frame buffer coupled to the plurality of ports and the repeater unit to buffer a packet received on a port in the set of ports.
Claim 10
Dependent Claim
76 words
The network device of claim 8, wherein the plurality of ports comprise half-duplex ports, and the repeater unit includes logic to jam the plurality of ports in response to detection of a collision by transmitting jam packets to the plurality of ports, and logic to transmit a buffered packet from the frame buffer after the jam packet, and the commands comprise a control field in the jam packets and a control field in the buffered packet.
Claim 11
Dependent Claim
89 words
The network device of claim 9, wherein the control field comprises an end of frame control field which carries a clear-to-send command to one end station coupled to the set of ports other than the port from which the buffered packet was received, and a backoff command to other ports in the plurality of ports, so that the one end station receiving the clear-to-send command in the end of frame control field of the buffered packet has an opportunity to send a packet without collision after the buffered packet.
Claim 12
Dependent Claim
56 words
The network device of claim 1, wherein the plurality of ports comprise full-duplex ports, and the repeater unit includes logic to transmit a packet received on a first selected port in the set of ports to the plurality of ports during detection of a collision, and the commands comprise a control field in the transmitted packet.
Claim 13
Dependent Claim
35 words
The network device of claim 11, including a frame buffer coupled to the plurality of ports and the repeater unit to buffer a packet received on a second selected port in the set of ports.
Claim 14
Dependent Claim
100 words
The network device of claim 12, wherein the control field comprises an end of frame control field which carries a clear-to-send command to one end station coupled to a third selected port in the set of ports other than the first and second selected ports, and a wait command to other ports in the plurality of ports, so that the one end station receiving the clear-to-send command in the end of frame control field of the packet from the first selected port has an opportunity to send a packet without collision after receiving the packet from the first selected port.
Claim 15
Dependent Claim
45 words
The network device of claim 13, wherein the control field carries a wait and retry command to ports in the set of colliding ports, other than the first, second and third selected ports indicating to end stations to retry after waiting for a clear-to-send command.
Claim 16
Dependent Claim
60 words
The network device of claim 1, wherein the repeater logic assigns opportunities to retry packets to ports in the set of ports, and said opportunities last a slot time defined as a delay parameter long enough to allow for a round trip transmission of a packet from a port in the plurality of ports to an end station and back.
Claim 17
Dependent Claim
37 words
The network device of claim 15, including: delay parameter negotiation logic, coupled to the repeater unit and the plurality of ports, which communicates with end stations coupled to the plurality of ports to determine the slot time.
Claim 18
Dependent Claim
45 words
The network device of claim 16, wherein the delay parameter negotiation logic communicates with end stations coupled to the plurality of ports to determine an inter-frame gap time which the repeater unit waits between an end of a packet and a transmission of another packet.
Claim 19
Dependent Claim
61 words
The network device of claim 1, wherein the repeater unit includes logic which issues clear-to-send commands in a sequence giving all the ports in the set of ports respective opportunities to send packets, and after all ports in set of ports have had an opportunity to send a packet, issues clear-to-send commands to all enabled ports in the plurality of ports.
Claim 20
Dependent Claim
65 words
The network device of claim 1, including: delay parameter negotiation logic, coupled to the repeater unit and the plurality of ports, which upon detection of a new link to an end station on a port, sends a delay parameter packet to the end station, receives a response packet from the end station, and updates delay parameters for the network in response to the response packet.
Claim 21
Dependent Claim
25 words
The network device of claim 19, wherein the delay parameter negotiation logic includes logic to broadcast updated delay parameters to end stations in the network.
Claim 22
Dependent Claim
41 words
The network device of claim 1, wherein the repeater unit includes logic to periodically assign opportunities to send packets, if no activity is detected on the plurality of ports, to all end stations coupled enabled ports in the plurality of ports.
Claim 23
Dependent Claim
184 words
A network device, comprising: a plurality of ports; a repeater unit including logic coupled to the plurality of ports which monitors activity on the plurality of ports i) to periodically issue commands to all enabled ports in the plurality of ports in parallel indicating clear to send status to end stations coupled to the plurality of ports, ii) to transmit a packet received without collision on one port to all other enabled ports in the plurality of ports, and ii) to detect a collision between packets received on a set of ports in the plurality of ports, to identify the ports in the set of ports, and to issue commands to end stations coupled to ports in the set of ports to resolve the collision, the commands assigning opportunities to the ports in the set of ports to send a packet without collision; and delay parameter negotiation logic, coupled to the repeater unit and the plurality of ports, which communicates with end stations coupled to the plurality of ports to determine delay parameters for use by the repeater unit to detect and resolve collisions.
Claim 24
Dependent Claim
184 words
A network device, comprising: a plurality of ports; a repeater unit including logic coupled to the plurality of ports which monitors activity on the plurality of ports i) to periodically issue commands to all enabled ports in the plurality of ports in parallel indicating clear to send status to end stations coupled to the plurality of ports, ii) to transmit a packet received without collision on one port to all other enabled ports in the plurality of ports, and ii) to detect a collision between packets received on a set of ports in the plurality of ports, to identify the ports in the set of ports, and to issue commands to end stations coupled to ports in the set of ports to resolve the collision, the commands assigning opportunities to the ports in the set of ports to send a packet without collision; and delay parameter negotiation logic, coupled to the repeater unit and the plurality of ports, which communicates with end stations coupled to the plurality of ports to determine delay parameters for use by the repeater unit to detect and resolve collisions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-06-22 | 2001-12-22 | 2002-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-06-22 | 2005-12-22 | 2006-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-06-22 | 2009-12-22 | 2010-06-23 | $7700.00 | Window Closed / Lapsed |