US 5,471,461 A · Digital communication network with a moderator station election process

Abstract

A moderator on a communication network periodically transmits a set of parameters for a protocol that is used to communicate over the network. Each node on the network compares the set of protocol parameters from the moderator to a set of parameters stored in that node. If the sets of parameters at a given node do not match, that given node ceases transmitting messages over the network until either the set of protocol parameters from the moderator match the stored set of parameters, or a matching set of parameters is stored in the node. Typically the active node that is assigned the lowest numerical network address functions as the moderator. However, an automatic process is utilized to prevent a node with a non-matching set of the protocol parameters from becoming the moderator for more than a brief period of time. An override procedure is provided to force all the nodes on the network to adopt a common set of protocol parameters in the event that the automatic process fails.

Claims15

Dependent claims

In a communication network having a plurality of nodes connected to a medium with each node being assigned a unique network address within a range of numerical values, and wherein one of the plurality of nodes is designated as a moderator which periodically transmits a set of communication protocol parameter values over the medium, a method by which a given node determines whether to function as the moderator comprising:

receiving messages sent by other nodes over the medium, each message including an identification of the network address from which the message originated;
determining from received messages whether another node is assigned a network address that is closer to one extreme of the range of numerical values than a network address assigned to the given node;
and
functioning as the moderator by periodically transmitting communication protocol parameter values, when the given node has a network address that is closer to the one extreme of the range of numerical values than all other nodes which are sending messages over the medium.

1 more element

In a communication network having a plurality of nodes connected to exchange messages over a medium with each node being assigned a unique network address, and each message including an identification of the network address from which the message originated, and wherein a moderator node periodically transmits moderator messages over the medium, a method by which a given node determines whether to function as the moderator node comprising:

(a) receiving a first moderator message containing a first set of protocol parameter values transmitted over the medium by the moderator node;
(b) comparing the first set of protocol parameter values transmitted by the moderator node to a second set of protocol parameter values stored in the given node;
(c) disabling transmission of messages over the medium by the given node when the first and second sets of protocol parameter values are not substantially identical;
(d) while transmission of messages from the given node continues to be disabled, monitoring the medium for transmission of messages by other nodes, and upon detecting that no messages are being sent over the medium for a defined period of time, starting a timer to time a watch interval;
(e) if a second moderator message containing a third set of protocol parameter values is received by the given node during said watch interval, and the third set of protocol parameter values contained in said second moderator message do not match the second set of protocol parameter values stored in the given node, terminating the first timer and returning to step (d);
(f) when the first timer times out, determining from activity on the medium whether another node is assigned a network address with a lower numerical value than the network address assigned to the given node;
(g) functioning as the moderator node by periodically transmitting further moderator messages which contain further protocol parameter values, when no other node that is sending messages over the medium has a lower numerical network address than the given node;
and
(h) functioning as a non-moderator node when another node is sending messages over the medium that have a lower numerical network address than the given node.

6 more elements

In a communication network having a plurality of nodes connected to a medium with each node being assigned a unique numerical network address, each message including an identification of the network address from which the message originated, and wherein one of the plurality of nodes is designated as a moderator node which periodically transmits moderator messages over the medium, a method by which a given node determines whether to function as the moderator node comprising:

if the given node is not functioning as the moderator, the given node performs steps of:
(a) receiving a first moderator message containing a first set of protocol parameter values transmitted over the medium by an existing moderator node,
(b) comparing the first set of protocol parameter values transmitted by said existing moderator to a second set of protocol parameter values stored in the given node,
(c) disabling transmission of messages over the medium by the given node when the first and second sets of protocol parameter values are not substantially identical,
(d) while transmission of messages from the given node continues to be disabled, monitoring the medium for transmission of messages by other nodes, and upon detecting that no messages are being sent over the medium for a first period of time, starting a first timer to time a first interval,
(e) if a second moderator message containing a third set of protocol parameter values is received by the given node during the first interval, and the third set of protocol parameter values contained in said second moderator message do not match the second set of protocol parameter values stored in the given node, terminating the first timer and returning to step (d),
(f) when the first timer times out, determining from activity on the medium whether another node is assigned a network address with a lower numerical value than the network address assigned to the given node,
(g) functioning as the moderator node by periodically transmitting further moderator messages which contain further protocol parameter values, when no other node that is sending messages over the medium has a lower numerical network address than the given node, and
(h) functioning as a non-moderator node when another node is sending messages over the medium that have a lower numerical network address than the given node;
and if the given node is functioning as the moderator node, the given node performs steps of:
(i) upon detecting that only moderator messages are being sent over the medium for a second period of time, disabling transmission of messages over the medium and starting a second timer to time a second interval that is longer than the first interval,
(j) if a third moderator message containing a fourth set of protocol parameter values is received by the given node during the second interval and the fourth set of protocol parameter values contained in said third moderator message do not match the second set of protocol parameter values stored in the given node, terminating the second timer and entering step (d) as a non-moderator node, and otherwise
(k) when the second timer times out, determining from activity on the medium whether another node is assigned a network address with a lower numerical value than the network address assigned to the given node,
(l) functioning again as the moderator node by periodically transmitting further moderator messages which contain further protocol parameter values, if no other node that is sending messages over the medium has a lower numerical network address than the given node, and
(m) functioning as a non-moderator node when another node is sending messages over the medium that have a lower numerical network address than the given node.

12 more elements

Dependencies are inferred from the claim text.

Digital communication network with a moderator station election process

Life of this patent

Digital communication network with a moderator station election process

Life of this patent

Abstract

Claims15