Method and apparatus for the detection and regeneration of a lost token in a token based data communications network

Claim 2

In a token-passing, ring-based data communications network, a method for the detection and regeneration of a lost token having the step of monitoring the communication network at each node having a pending packet transmission for detecting the loss of the token, said method being characterized by the steps of transmitting, at each monitoring node detecting the loss of the token, a data packet without a token, said data packet uniquely identifying the transmitting node as the source, stripping at each such transmitting node, . all incoming data from the network, transmitting a new token upon successful receipt of the transmitted data packet by the source node, and falling back to an arbitration method if the transmitted data packet is not received within a predetermined time out period.

Claim 3

The method of claim 1 wherein said falling back step is further characterized by the step of delaying transmission of a next data packet for a probabilistically determined period of time, the mean time of said probabilistic approach increasing with each unsuccessful transmission attempt.

Claim 4

The method of claim 1 further characterized in that said monitoring step determines the loss of the token based upon at least one of a token transit time around the ring based network wherein the token is not used, a maximum allowable data packet dura - tion, and a multiplicative product of the maximum number of nodes and the maximum packet duration.

Claim 5

In a token-passing, ring-based data communications system, a method for the detection and regeneration of a lost token having the steps of monitoring the communications network at each node connected to the network and having a data packet for transmission for detecting the loss of the token, and characterized in that said monitoring step bases said loss of the token upon at least one of a token transit time around the ring-based network during which time the token is not used by any node, a maximum allowable data packet duration, and the multiplicative product of the maximum number of nodes allowable on the network and the maximum packet duration, and further characterized by the steps of transmitting, at each node detecting the loss of the token, a data packet not including a token, which packet uniquely identifies the transmitting node as the source of the data packet, stripping, at each such transmitting node, all incoming data from the communications network, transmitting a new token upon successful receipt of the transmitted data packet, said successful receipt being the recognition of the node as the source of the data packet, falling back to an arbitration method when the transmitted data packet is not successfully received within a predetermined time out period, said arbitration method including delaying transmission of a next data packet for a probabilistically determined period of time, the mean time of said probabilistically determined period increasing with each unsuccessful attempt to transmit and receive a data packet on said ring-based data communications network.

Claim 6

In a token-passing, ring-based data communications system, a method for the detection and regeneration of a lost token having the steps of monitoring the communications network at each node connected to the network and having a data packet for transmission for detecting the loss of the token, and characterized in that said monitoring step bases said loss of the token upon at least one of a token transit time around the ring-based network during which time the token is not used by any node, a maximum allowable data packet duration, and the multiplicative product of the maximum number of nodes allowable on the network and the maximum packet duration, and further characterized by the steps of transmitting, at each node detecting the loss of the token, a data packet not including a token, which packet uniquely identifies the transmitting node as the source of the data packet, stripping, at each such transmitting node, all incoming data from the communications network, transmitting a new token upon successful receipt of the transmitted data packet, said successful receipt being the recognition of the node as the source of the data packet, falling back to an arbitration method when the transmitted data packet is not successfully received within a predetermined time out period, said arbitration method including delaying transmission of a next data packet for a probabilistically determined period of time, the mean time of said probabilistically determined period increasing with each unsuccessful attempt to transmit and receive a data packet on said ring-based data communications network.

Claim 7

A token-passing ring-based data communications network having means for detecting and regenerating a lost token comprising means for monitoring the communications network at each node having a pending packet transmission, for detecting the loss of the token, and characterized by means for transmitting, at each node detecting the loss of a token, a data packet not including a token which packet uniquely identifies the transmitting node as the source, means for stripping all incoming data from the communications network in response to the transmission of a said data packet without a token, said transmitting means further having means for transmitting a new token upon successful receipt of the transmitted data packet, and means for instituting an arbitration method if the transmitted data packet is not received within a predetermined time out period.

Claim 8

A token-passing ring-based data communications network having means for detecting and regenerating a lost token comprising means for monitoring the communications network at each node having a pending packet transmission, for detecting the loss of the token, and characterized by means for transmitting, at each node detecting the loss of a token, a data packet not including a token which packet uniquely identifies the transmitting node as the source, means for stripping all incoming data from the communications network in response to the transmission of a said data packet without a token, said transmitting means further having means for transmitting a new token upon successful receipt of the transmitted data packet, and means for instituting an arbitration method if the transmitted data packet is not received within a predetermined time out period.

Claim 9

The apparatus of claim 5 wherein said instituting means is further characterized by means for probabilistically determining a delay period, the mean time of the delay period increasing with each unsuccessful transmission attempt, and means for delaying transmission of a next packet of data without a token for said probabilistically determined delay period.

Claim 10

The apparatus of claim 5 further wherein said monitoring means is characterized by means for determining the loss of the token while taking into account at least one of a token transit time around the ring-based network wherein the token is not used, a maximum allowable data packet duration, and a multiplicative product of the maximum number of nodes allowed on the network and the maximum packet duration.

Claim 11

The apparatus of claim 5 wherein said transmitting means is further characterized by means for determining the successful receipt of a transmitted data packet by recognizing the source of the packet as being said transmitting node.

Claim 12

The method of claim 1 wherein said monitoring step is further characterized by employing a packet timing period and a token timing period for determining the loss of the token.

Claim 13

The apparatus of claim 5 further wherein said monitoring means is characterized by a packet timer, and a token timer, said packet timer and said token timer being initiated when the node has a pending data packet transmission, said token timer having a duration equal to the multiplicative product of the maximum number of nodes on the network and the maximum packet duration, and said packet timer having a time duration greater than the sum of the time duration of a maximum size data packet and the maximum transit time around the network.