EP0452223A2
Expired / Lapsed
EP
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Telecommunications network with plesiochronous transfer mode
Assignee: Digital Equipment Corp
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Filing: 1991-04-12
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Granted: —
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Expires: 2011-04-12
Abstract
Abstract A telecommunications network of the type having links with long propagation delay uses an asynchronous transfer mode in which small, fixed-length blocks of information (cells) are transferred at very high speed. Each long-haul hop within the network is phase-locked to a fixed period, and time slots of a granularity of one cell are pre-allocated to the virtual circuits. The network operates in a near-synchronous (plesiochronous) manner. By pre-allocating cells, it is assured that the cells will not arrive at a faster rate than that at which each receiving node can forward them on to the next hop. When bursts of heavy traffic occur, the network responds by slowing or limiting access, rather than by loss of data at intermediate nodes due to buffer overflow.
Inventors
- 👤 Fred R. Goldstein
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 09:13
CPC Classifications
H; H04; H04L; H04L47/00; H04L47/10; H04J; H04J2203/00; H04J2203/0001; H04J2203/0089; H04J2203/0091; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5672; H04L2012/5674; H04L2012/5675
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
91 words
A communication network having a plurality of links between nodes, comprising: a transmitter sending repetitive frames to one of said links, said frames being of fixed length related to a propagation delay over said one link and containing a large number of cells, each cell containing identifcation of a virtual channel and information for a message transmitted for said virtual channel; a receiver defining repetitive frames phase-locked with said transmitter and receiving information in said cells for forwarding on other of said links according to said identification of said virtual channels.
Claim 2
Dependent Claim
35 words
A network according to claim 1 wherein said fixed length is an integral multiple of a basic control period representing more than said propagation delay for a round trip on said one of said links.
Claim 3
Dependent Claim
38 words
A network according to claim 1 wherein nodes at each end of said one link have buffers and said propagation delay may be longer than the fill time of said buffers at the transmission rate of said link.
Claim 4
Dependent Claim
15 words
A network according to claim 1 wherein said link is a serial fibre optic link.
Claim 5
Dependent Claim
20 words
A network according to claim 1 wherein said transmitter funnels messages from a number of said nodes into said link.
Claim 6
Dependent Claim
50 words
A network according to claim 1 wherein there are at least two of said links, each having a separate said transmitter and a separate said receiver, each of said at least two links having a frame of a fixed length which is an integral multiple of a basic fixed length.
Claim 7
Dependent Claim
23 words
A network according to claim 1 wherein each said frame of fixed length contains a plurality of said cells for said virtual channel.
Claim 8
Dependent Claim
31 words
A network according to claim 1 wherein said frame contains slip cells for adding or omitting time periods for synchronizing said frame of said receiver with said frame of said transmitter.
Claim 9
Dependent Claim
23 words
A network according to claim 1 wherein said cells of said frame are allotted to channels according to the number of said channels.
Claim 10
Independent Claim
119 words
A method of transmitting information wherein messages from a first group of terminals are funneled through first and second intermediate nodes to a second group of terminals, using time-division multiplexing, comprising the steps of: a) maintaining synchronized transmission from said first intermediate node and reception at said second intermediate node of repetitive message frames having a frame period related to the time of propagation of signals from said first to said second intermediate nodes; b) inserting cells from said messages in time slots in said message frames at said first intermediate node, with identification of the messages; c) allocating said time slots to said messages on a dynamic basis depending upon the number of said messages to be transmitted.
Claim 11
Dependent Claim
30 words
A method according to claim 10 including the step of synchronizing a receiver at said second intermediate node with said frame period by a clock at said second intermediate node.
Claim 12
Dependent Claim
36 words
A method according to claim 10 wherein said frame period is an integral multiple of a basic period representing more than said time of propagation for a round trip between said first and second intermediate nodes.
Claim 13
Dependent Claim
36 words
A method according to claim 10 wherein said first and second intermediate nodes have buffers and said time of propagation is longer than the fill time of said buffers at the transmission rate of said frames.
Claim 14
Dependent Claim
66 words
A method according to claim 10 including a third intermediate node, and including the steps of: maintaining synchronized transmission from said second intermediate node and reception at said third intermediate node of repetitive message frames having a time period which is an integral multiple of said frame period; and inserting cells from said messages in time slots in said message frames at said second intermediate node.
Claim 15
Dependent Claim
27 words
A method according to claim 10 wherein each said message frame of fixed length contains a plurality of said cells for a given one of said messages.
Claim 16
Dependent Claim
14 words
A method according to claim 10 wherein said transmission is by a serial link.
Claim 17
Dependent Claim
15 words
A method according to claim 16 wherein said serial link is a fibre optic link.
Claim 18
Independent Claim
151 words
A method of transmitting data, comprising the steps of: a) creating a repetitive message frame having a number of time slots for use in transmitting between first and second intermediate nodes, said message frame having a length related to the round trip time for transmission from said first to said second node and return to said first node; b) synchronizing the starting point and said slots of said repetitive message frame at each of said first and second intermediate nodes; c) inserting in said slots information for message being sent from remote terminals via said first intermediate node to said second intermediate node for forwarding to other remote terminals; d) labelling each of said slots with an identification of the messages for which information is inserted in said slots; and e) allotting a number of said slots in each of said message frames in accordance with the number of said messages.
Claim 19
Dependent Claim
29 words
A method according to claim 18 wherein said message frame has a period which is an integral multiple of a basic period representing more than said round trip time.
Claim 20
Dependent Claim
37 words
A method according to claim 18 wherein said first and second intermediate nodes have buffers and said round trip time is longer than the fill time of said buffers at the transmission rate of said message frames.
References Cited (Backward Citations)
No citation records indexed.
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