EP0109964A1
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Synchronization in a communication network of interconnected rings
Assignee: International Business Machines Corp
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Filing: 1982-11-26
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Granted: —
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Expires: 2002-11-26
Abstract
Abstract in a network of communication rings (Rl ... R7, BB) interconnected by bridges (B1 ... B4), access to each ring is regulated by a circulating token which is normally issued at irregular intervals depending on occurence and length of messages. To enable communication of messages which have to be transmitted synchronously, i.e. at regular intervals, each ring has a synchronous bandwidth manager SBM which periodically issues a token for only synchronous information. Each SBM is located in a bridge node (13, 15) but only one of them which is located in a particular bridge node (15) is the master SBM from which all other SBM's are synchronized, using a synchronous token and/or special synchronization circuitry in each bridge. This allows to have a common period in the whole network for handling synchronous information, even if all rings have different bit rates.
Inventors
- 👤 Werner Klaus Dr. Bux
- 👤 Roy C. Dixon
- 👤 Ernst Dr. Rothauser
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 07:19
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/02; H04M9/022; H04M9/025; H04L; H04L12/00; H04L12/28; H04L12/46; H04L12/4637
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
146 words
Method of synchronization in a communication network consisting of a plurality of transmission rings interconnected by bridges, access to each ring being regulated by a token mechanism, each ring comprising a synchronous bandwidth manager called SBM which issues a priority token or frame for synchronous traffic of authorized stations at regular intervals, and in which network each ring is separately bit- synchronized and any ring can have a bit rate unrelated to that of the other rings, characterized in that - clocks in all SBMs are synchronized by one master SBM defining synchronous-traffic periods, via the transmission rings interconnecting the bridges and via interconnections in the bridges, and - each SBM issues a priority token or frame for synchronous traffic a given time after the begin of each synchronous-traffic period as defined by its clock but in synchronism with the independent bit clock of its ring.
Claim 2
Dependent Claim
146 words
Method of synchronization in a communication network consisting of a plurality of transmission rings interconnected by bridges, access to each ring being regulated by a token mechanism, each ring comprising a synchronous bandwidth manager called SBM which issues a priority token or frame for synchronous traffic of authorized stations at regular intervals, and in which network each ring is separately bit- synchronized and any ring can have a bit rate unrelated to that of the other rings, characterized in that - clocks in all SBMs are synchronized by one master SBM defining synchronous-traffic periods, via the transmission rings interconnecting the bridges and via interconnections in the bridges, and - each SBM issues a priority token or frame for synchronous traffic a given time after the begin of each synchronous-traffic period as defined by its clock but in synchronism with the independent bit clock of its ring.
Claim 3
Dependent Claim
45 words
Method in accordance with claim 1, characterized in that each bridge, recognition of the first synchronous token or frame after an asynchronous token or frame is used as synchronizing event and causes generation of a synchronization pulse for units further away from the master SBM.
Claim 4
Dependent Claim
55 words
Method in accordance with claim 2, characterized in that in each bridge, the bridge node of the ring closest to the master SBM issues a synchronization pulse upon recognition of a first synchronous token or frame, and transfers this synchronization pulse to any SBM of another ring having a bridge node in the same bridge.
Claim 5
Dependent Claim
54 words
Method in accordance with claim 1, characterized in that for at least one ring, start times of first synchronous tokens or frames are shifted by about one-half synchronous-traffic period with respect to the corresponding start times for rings connected to it by a bridge, for reducing transfer time of synchronous messages across the bridge.
Claim 6
Dependent Claim
27 words
Method in accordance with claim 1, characterized in that the master SBM is synchronized by pulses from a source located outside of the network of interconnected rings.
Claim 7
Dependent Claim
79 words
Method in accordance with claim 1, characterized in that in each synchronous-traffic period, in an interval starting two maximum frame durations prior to the regular issuance time of a first synchronous token or frame, each SBM makes a priority reservation in the next passing asynchronous frame to prevent issuance of another asynchronous token so that at the regular issuance time of the next synchronous token or frame, no asynchronous token or frame will be circulating on the respective ring.
Claim 8
Dependent Claim
61 words
Method in accordance with claim 6, characterized in that if an SBM, after making a priority reservation, recognizes an end delimiter of an asynchronous frame earlier than one maximum frame duration prior to the regular issuance time of the next synchronous token or frame, it issues a return asynchronous token to allow the transmission of one additional frame of asynchronous information.
Claim 9
Dependent Claim
126 words
Communication network consisting of a plurality of transmission rings interconnected by bridges, access to each ring being regulated by a token mechanism, each ring comprising a synchronous bandwidth manager SBM for issuing a priority token for synchronous traffic at regular intervals, each ring being independently bit-synchronized, characterized in that - each ring (R1...R7, BB) has one bridge node (13, 15, 17, 21) in each bridge (Bl...B4)) by which it is connected to other rings, - the SBM of each ring is combined with a bridge node of the respective ring, - one SBM (13) is the master SBM which is synchronized by its own master oscillator or an external clock (33) whereas all other SBMs are synchronized via a ring and/or bridge from the master SBM.
Claim 10
Dependent Claim
126 words
Communication network consisting of a plurality of transmission rings interconnected by bridges, access to each ring being regulated by a token mechanism, each ring comprising a synchronous bandwidth manager SBM for issuing a priority token for synchronous traffic at regular intervals, each ring being independently bit-synchronized, characterized in that - each ring (R1...R7, BB) has one bridge node (13, 15, 17, 21) in each bridge (Bl...B4)) by which it is connected to other rings, - the SBM of each ring is combined with a bridge node of the respective ring, - one SBM (13) is the master SBM which is synchronized by its own master oscillator or an external clock (33) whereas all other SBMs are synchronized via a ring and/or bridge from the master SBM.
Claim 11
Dependent Claim
125 words
Communication network in accordance with claim 8, characterized in that in each bridge except the one comprising the master SBM, the bridge node (17, 21) closest to the master SBM has means (Fig. 5) to recognize each first synchronous token or frame after an asynchronous token or frame, and to isssue a respective synchronization pulse on a connection (27, 27') to the other bridge nodes (13) within the same bridge for synchronizing the clocks (31) of their SBM's, and that the bridge node (15) combined with the master SBM issues together with each first synchronous token or frame a respective synchronization pulse on a connection (27, 27') to the other bridge nodes (13) in the same bridge for synchronizing the clocks (31) of their SBM's.
Claim 12
Dependent Claim
68 words
Communication network in accordance with claim 8, characterized in that each bridge node (15) combined with an SBM includes means (Fig. 4) for issuing a start pulse (t R ) for a synchronous token or frame in response to the bit clock pulse of its associated ring which next follows a clock pulse (t S ) of its synchronous-traffic clock (31) that is synchronized from the master SBM.
References Cited (Backward Citations)
EP0054077A1
Cited
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