Systems and methods for providing automatic network optimization with application variables

• US 7,453,906 B2
• Filed: 09/19/2002
• Issued: 11/18/2008
• Est. Priority Date: 09/19/2002
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Pyle, Harry S., Simonnet, Guillaume, Hasha, Richard L.
• Primary Examiner(s): Orgad; Edan
• Assistant Examiner(s): Wong; Blanche
• Application Number:
  US10/251,457
• Publication Number:
  US 20040081201A1
• Time in Patent Office: 2,252 Days
• Field of Search: None
• US Class Current: 370/469
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H04L 41/08 Configuration management of networks or network elements address allocation H04L61/50
• CPC Class Codes: H04L 69/03 Protocol definition or specification protocol conformance testing H04L1/244
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

Systems and methods for automatic network optimization with application variables are provided. Operation of a protocol stack, such as an SCP stack, relies upon a number of persistent variables, which are remembered over power and reset cycles, used in connection with controlling protocol timing and behavior. These application variables are handled at the network layer of the protocol and may be assigned values by an address space arbitrator, which is an entity responsible for managing the logical network. Each node member of a logical network maintains a set of values for its application variables. This set can be handled by the protocol'"'"'s network layer, and can be saved in persisted storage. Since the variable values may be modified asynchronously, they are treated as volatile and thus, when a variable is used, its value is obtained through an application interface exposed by a network layer, e.g., through polling. An exception to this procedure is a data link layer, which obtains some operating parameters on every call by the network layer. Optimization of application variables enables reliable operation of a logical network operating under low bandwidth network conditions, etc.

Claims

1. A method for automatically tuning a network having a protocol and a plurality of nodes forming a logical network, comprising:

receiving at least one value for at least one application variable, the at least one application variable representative of a network tuning parameter for the logical network and the at least one application variable additionally corresponding to a network time synchronization application variable, wherein at least one node of the plurality of nodes is configured to use the at least one value to detect and ignore replay messages; and

altering, based upon said at least one value corresponding to the network time synchronization application variable, at least one of protocol timing and network behavior relating to the at least one node of said plurality of nodes in said network.

2. A method according to claim 1, wherein said at least one application variable includes at least one of (A) a variable corresponding to a data link layer of the protocol, (B) a variable corresponding to network time synchronization of the logical network, (C) a variable corresponding to a network layer of the protocol and (D) a variable corresponding to a transport layer of the protocol.

3. A method according to claim 2, wherein a node of the network is in one of three time synchronization modes including a master mode, a subordinate mode and an unlocked mode, wherein the master mode uses a network time reference for other nodes, the subordinate mode locks onto a master node for a network time and the unlocked mode is not synchronized.

4. A method according to claim 2, wherein a node synchronizes its network time to a time provided in any network time assert message received for its associated network.

5. A method according to claim 2, wherein a variable corresponding to network time synchronization of the logical network includes at least one of a variable for (A) Poll Holdoff Delay, (B) Master Holdoff Delay, (C) Query Poll Time, (D) Master Declaration Wait, (E) Subordinate Declaration Wait, (F) Declaration Poll Time, (G) Master Response Wait and (H) Maximum Message Skew.

6. A method according to claim 2, wherein a variable corresponding to the network layer of the protocol includes at least one of a variable for (A) Slow Node Presence Base Id, (B) Fast Node Presence Refresh, (C) Fast Node Presence Timeout, (D) Slow Node Presence Refresh and (E) Slow Node Presence Timeout.

7. A method according to claim 2, wherein a variable corresponding to the network layer of the protocol includes at least one of a variable for (A) Message Assembly Timeout and (B) Network Control Protocol Transmit Holdoff Delay.

8. A method according to claim 2, wherein a variable corresponding to the transport layer of the protocol includes at least one of a variable for (A) Max Request Retry Count, (B) Reply Wait Timeout, (C) Max Reply Retry Count and (D) Reply Acknowledgment Wait Timeout.

9. A method according to claim 2, wherein a variable corresponding to the transport layer of the protocol determines at least one of (A) time out conditions after dropping a message and (B) how long to wait before re-sending at least one of a request, reply and reply acknowledgement.

10. A method according to claim 2, wherein a variable corresponding to the data link layer of the protocol determines at least one of (A) backoff timeout, (B) acknowledgment retry count and (C) broadcast burst count.

11. A method according to claim 1, wherein said at least one application variable includes at least one of (A) a variable corresponding to a data link layer, (B) a variable corresponding to a network layer and (C) a variable corresponding to a transport layer.

12. A method according to claim 11, wherein said at least one variable corresponding to a network layer includes at least one variable corresponding to (A) a variable corresponding to time and (B) a variable corresponding to presence.

13. A method according to claim 1, wherein each node tracks the presence of all other nodes in the network by way of at least one variable corresponding to the network layer.

14. A method according to claim 1, wherein said at least one application variable is persistently stored.

15. A method according to claim 1, wherein the at least one application variable is handled at a network layer of the protocol.

16. A method according to claim 1, further comprising:

assigning values by an Address Space Arbitrator (ASA), wherein the ASA is an entity responsible for managing the network.

17. A method according to claim 16, further comprising handling the servicing of at least one application variable by a network control protocol handler, a component of a network layer, wherein said handling includes at least one of (A) handling by the network control protocol handler the persistence of a value of an application variable in storage, (B) providing by the network control protocol handler the value of a variable to a protocol layer other than the network layer through an application interface, (C) accepting by the network control protocol handler a new value of an application variable at the time a device is assigned to a logical network by an ASA, (D) accepting and acknowledging by the network control protocol handler a value of a new variable when instructed by the ASA and (E) providing a value of an application variable when asked by the ASA.

18. A method according to claim 16, wherein the ASA updates the at least one application variable when a node is assigned to its logical network.

19. A method according to claim 16, wherein the ASA broadcasts the at least one application variable to all nodes on the logical network through a Write message and each node acknowledges the message.

20. A method according to claim 16, wherein the ASA unicasts Read and Write variable messages to verify and update a node.

21. A method according to claim 1, wherein said altering is transparent to a layer other than a network layer of the protocol.

22. A method according to claim 1, wherein said altering includes dynamically tuning and optimizing the protocol based upon a determination that a specific operating condition exists in the network.

23. A method according to claim 22, wherein said specific operating condition includes at least one of (A) low bandwidth operation of the physical medium of the network, (B) potential noise (C) a dynamic determination that there is a weak transmitter node (D) a dynamic determination that there is a weak receptor node, (E) degraded signal quality on a communications path, (F) amount of activity on the network and (G) a specific combination of number and kinds of nodes.

24. A method according to claim 23, wherein said at least one application variable includes at least one of (A) an adaptive back off parameter, (B) a timing window for network communications and (C) a threshold for a determination that there is at least one of said specific operating conditions.

25. A method according to claim 1, wherein said altering includes cross-correlating with respect to the node segments of the network which node paths are of good quality and which node paths are of poor quality.

26. A method according to claim 25, wherein said cross-correlating includes taking into account the rate of network traffic.

27. A method according to claim 1, wherein each node member of the logical network maintains a set of at least one value of least one application variable associated with the node member.

28. A method according to claim 27, wherein the set of at least one value is handled by a network layer of the protocol, and saved in persisted storage.

29. A method according to claim 27, wherein the at least one value of at least one application variable is one of (A) specific to the physical network, (B) specific to the logical network and (C) specific to a node on the logical network.

30. A method according to claim 1, wherein the at least one value is modified asynchronously.

31. A method according to claim 1, wherein said receiving the at least one value includes receiving said at least one value through an application interface exposed by a network layer of the protocol.

32. A method according to claim 31, wherein with respect to a data link layer of said protocol, said receiving at least one value includes receiving at least one value of at least one application variable on every call to the application interface.

33. A method according to claim 1, wherein the associated protocol is one of SCP, x10 and CEBus®

.

34. A method according to claim 1, wherein a physical network underlying the logical network is one of a power line carrier network, a radio frequency network and an infrared transmission network.

35. A method according to claim 1, wherein when the values of the application variables are altered, further comprising ensuring that the values are consistent across all nodes in the network.

36. A method according to claim 1, wherein said at least one application variable at least one of (A) is set during a node acquisition step, (B) is set by default into one of a device and object and (C) is changed during optimization of the network dynamically.

37. A method according to claim 36, wherein when said at least one application variable is set by default into a one of a device and object, a subset of said at least one application variable is left blank.

38. A method according to claim 1, wherein the at least one application variable comprises a variable length table maintained by the network layer.

39. A method according to claim 1, wherein the at least one application variable is at least one of (A) logical network specific, (B) specific to a particular physical network underlying the logical network and (C) node specific.

40. A method according to claim 1, wherein said at least one application variable is at least one protocol variable.

41. A method according to claim 40, further comprising receiving a network control protocol read variables request message requesting reading of at least one protocol variable.

42. A method according to claim 41, wherein fields of the network control protocol read variables request message include at least one of (A) Network time, (B) Protocol variables requested, (C) Node ID of target device, (D) Request counter, and (E) Message authentication code.

43. A method according to claim 41, further comprising receiving a network control protocol read variables response message responding to a network control protocol read variables request message.

44. A method according to claim 43, wherein fields of the network control protocol read variables response message include at least one of (A) Network time, (B) Protocol variables requested, (C) Node ID of replying device, (D) Request counter, (E) Protocol variables values stream, and (F) Message authentication code.

45. A method according to claim 40, further comprising receiving a network control protocol write variables request message requesting writing of at least one protocol variable.

46. A method according to claim 45, wherein fields of the network control protocol write variables request message include at least one of (A) Network time, (B) Protocol variables requested, (C) Node ID of target device, (D) Request counter, (E) Protocol variables values stream and (F) Message authentication code.

47. A method according to claim 45, further comprising receiving a network control protocol write variables response message responding to a network control protocol write variables request message.

48. A method according to claim 47, wherein fields of the network control protocol write variables response message include at least one of (A) Network time, (B) Protocol variables requested, (C) Node ID of replying device, (D) Request counter and (E) Message authentication code.

49. A method according to claim 40, further comprising receiving a broadcast request message, whereby in response, replying nodes back off their reply up to a delay amount, defined by a delay application variable.

50. A method according to claim 40, wherein said at least one protocol variable is used with at least one default value including a network time poll holdoff delay, a network time master holdoff delay, a network time query poll time, a network time master declaration wait, a network time subordinate declaration wait, a network time declaration poll time, a network time master response wait and a network time maximum message skew.

51. A method according to claim 1, wherein said altering includes ignoring a message if there is a threshold difference in time between a send time for the message and a receive time for the message.

52. A method according to claim 1, further comprising assigning a network time by a time master to a message, wherein the network time is a unique number that is reset frequently to prevent replay attack.

53. A method according to claim 1, wherein based on windowing, spoofing is protected against by jamming an imposter message.

54. A method according to claim 1, further comprising tracking the presence of all other nodes on the network in accordance with said at least one application variable.

55. At least one of an operating system, driver code, an application programming interface, a tool kit and a processing device for providing the method of automatically tuning a network of claim 1.

56. A modulated data signal carrying computer executable instructions for performing the method of claim 1.

57. A computer readable storage medium including computer readable instructions for automatically tuning a network having a protocol and a plurality of nodes forming a logical network, the computer readable storage medium comprising:

instructions for receiving at least one value for at least one application variable, the at least one application variable representative of a network tuning parameter for the logical network and the at least one application variable additionally corresponding to a network time synchronization application variable, wherein at least one node of the plurality of nodes is configured to use the at least one value to detect and ignore replay messages; and

instructions for altering, based upon said at least one value corresponding to the network time synchronization application variable, at least one of protocol timing and network behavior relating to the at least one node of said plurality of nodes in said network.

58. A computer readable medium according to claim 57, wherein said at least one application variable includes at least one of (A) a variable corresponding to a data link layer, (B) a variable corresponding to a network layer and (C) a variable corresponding to a transport layer.

59. A computer readable medium according to claim 58, wherein said at least one variable corresponding to the network layer includes at least one of (A) a variable corresponding to time and (B) a variable corresponding to presence.

60. A computer readable medium according to claim 58, wherein a variable corresponding to the transport layer determines at least one of (A) time out conditions for dropping a message and (B) how long to wait before re-sending at least one of a request, reply and reply acknowledgement.

61. A computer readable medium according to claim 58, wherein a variable corresponding to the data link layer determines at least one of (A) backoff timeout, (B) acknowledgment retry count and (C) broadcast burst count.

62. A computer readable medium according to claim 58, wherein each node tracks the presence of all other nodes in the logical network by way of at least one variable corresponding to the network layer.

63. A computer readable medium according to claim 57, wherein said at least one application variable is persistently stored.

64. A computer readable medium according to claim 57, wherein the at least one application variable is handled at a network layer of the protocol.

65. A computer readable medium according to claim 57, further comprising:

assigning values by an Address Space Arbitrator (ASA), wherein the ASA is an entity responsible for managing the network.

66. A computer readable medium according to claim 65, further comprising handling the servicing of at least one application variable by a network control protocol handler, a component of a network layer, wherein said handling includes at least one of (A) handling by the network control protocol handler the persistence of a value of an application variable in storage, (B) providing by the network control protocol handler the value of a variable to a protocol layer other than the network layer through an application interface, (C) accepting by the network control protocol handler a new value of an application variable at the time a device is assigned to a logical network by an ASA, (D) accepting and acknowledging by the network control protocol handler a value of a new variable when instructed by the ASA and (E) providing a value of an application variable when asked by the ASA.

67. A computer readable medium according to claim 65, wherein the ASA updates the at least one application variable when a node is assigned to its logical network.

68. A computer readable medium according to claim 65, wherein the ASA broadcasts the at least one application variable to all nodes on the logical network through a Write message and each node acknowledges the message.

69. A computer readable medium according to claim 65, wherein the ASA unicasts Read and Write variable messages to verify and update a node that has missed a broadcast update.

70. A computer readable medium according to claim 57, wherein said altering is transparent to a layer other than a network layer of the protocol.

71. A computer readable medium according to claim 57, wherein said altering includes dynamically tuning and optimizing the protocol based upon a determination that a specific operating condition exists in the network.

72. A computer readable medium according to claim 71, wherein said specific operating condition includes at least one of (A) low bandwidth operation of the physical medium of the network, (B) potential noise (C) a dynamic determination that there is a weak transmitter node (D) a dynamic determination that there is a weak receptor node, (E) degraded signal quality on a communications path, (F) amount of activity on the network and (G) a specific combination of number and kinds of nodes.

73. A computer readable medium according to claim 72, wherein said at least one application variable includes at least one of (A) an adaptive back off parameter, (B) a timing window for network communications and (C) a threshold for a determination that there is at least one of said specific operating conditions.

74. A computer readable medium according to claim 57, wherein said altering includes cross-correlating with respect to the node segments of the network which node paths are of good quality and which node paths are of poor quality.

75. A computer readable medium according to claim 74, wherein said cross-correlating includes taking into account the rate of network traffic.

76. A computer readable medium according to claim 57, wherein each node member of the logical network maintains a set of at least one value for at least one application variable associated with the node member.

77. A computer readable medium according to claim 76, wherein the set of values is handled by a network layer of the protocol, and saved in persisted storage.

78. A computer readable medium according to claim 57, wherein the at least one value is modified asynchronously.

79. A computer readable medium according to claim 57, wherein said receiving the at least one value includes receiving said at least one value through an application interface exposed by a network layer of the protocol.

80. A computer readable medium according to claim 79, wherein with respect to a data link layer of said protocol, said receiving includes receiving at least one value of an application variable on every call to the application interface.

81. A computer readable medium according to claim 57, wherein the protocol is one of SCP, x10 and CEBus®

.

82. A computer readable medium according to claim 57, wherein a physical network underlying the logical network is one of a power line carrier network, a radio frequency network and an infrared transmission network.

83. A computer readable medium according to claim 57, wherein when application variables are altered, further comprising ensuring that the values are consistent across all nodes in the network.

84. A computer readable medium according to claim 57, wherein said at least one application variable at least one of (A) is set during a node acquisition step, (B) is set by default into one of a device and object and (C) is changed during optimization of the network dynamically.

85. A computer readable medium according to claim 57, wherein the at least one application variable comprises a variable length table maintained by the network layer.

86. A computer readable medium according to claim 57, wherein the at least one application variable is at least one of (A) logical network specific, (B) specific to a particular physical network underlying the logical network and (C) specific to a node of the logical network.

87. A computer readable medium according to claim 57, wherein said at least one application variable is at least one protocol variable.

88. A computer readable medium according to claim 87, further comprising receiving a network control protocol read variables request message requesting reading of at least one protocol variable.

89. A computer readable medium according to claim 88, further comprising receiving a network control protocol read variables response message responding to a network control protocol read variables request message.

90. A computer readable medium according to claim 87, further comprising receiving a network control protocol write variables request message requesting writing of at least one protocol variable.

91. A computer readable medium according to claim 90, further comprising receiving a network control protocol write variables response message responding to a network control protocol write variables request message.

92. A computer readable medium according to claim 87, further comprising receiving a broadcast request message, whereby in response, replying nodes back off their reply up to a delay amount, defined by a delay application variable.

93. A computer readable medium according to claim 57, wherein said altering includes ignoring a message if there is a threshold difference in time between a send time for the message and a receive time for the message.

94. A computer readable medium according to claim 57, further comprising further comprising assigning a network time by a time master to a message, wherein the network time is a unique number that is reset frequently to prevent replay attack.

95. A computer readable medium according to claim 94, wherein based on windowing, spoofing is protected against by jamming an imposter message.

96. A computer readable medium according to claim 57, further comprising tracking the presence of all other nodes on the network in accordance with said at least one application variable.

97. At least one computer readable medium according to claim 57, wherein said modules are included in at least one of an application programming interface (API), driver code, an operating system and an application.

98. A distributed computing system capable of automatically tuning a network having a protocol and a plurality of nodes forming a logical network, comprising:

at least one application variable representative of a network tuning parameter for the logical network corresponding to each node of the plurality of nodes, at least one value for the at least one application variable, wherein the at least one application variable additionally corresponds to network time synchronization application variable, further wherein each node of the plurality of nodes is configured to use the at least one value to detect and ignore replay messages; and

wherein based upon said at least one value, at least one of protocol timing and network behavior relating to each node of said plurality of nodes in said network is altered.

99. A distributed computing system according to claim 98, wherein said at least one application variable includes at least one of (A) a variable corresponding to a data link layer, (B) a variable corresponding to a network layer and (C) a variable corresponding to a transport layer.

100. A distributed computing system according to claim 99, wherein said at least one application variable corresponding to the network layer includes at least one of (A) a variable corresponding to network time and (B) a variable corresponding to presence.

101. A distributed computing system according to claim 99, wherein a variable corresponding to the transport layer determines at least one of (A) time out conditions after dropping a message and (B) how long to wait before re-sending at least one of a request, reply and reply acknowledgement.

102. A distributed computing system according to claim 99, wherein a variable corresponding to the data link layer determines at least one of (A) backoff timeout, (B) acknowledgment retry count and (C) broadcast burst count.

103. A distributed computing system according to claim 99, wherein each node tracks the presence of all other nodes in the network by way of at least one variable corresponding to the network layer.

104. A distributed computing system according to claim 98, wherein said at least one application variable is persistently stored.

105. A distributed computing system according to claim 98, wherein the at least one application variable is handled at a network layer of the protocol.

106. A distributed computing system according to claim 98, further comprising:

an Address Space Arbitrator (ASA), an entity responsible for managing the network, wherein the ASA assigns values to said at least one application variable.

107. A distributed computing system according to claim 106, further comprising:

a network control protocol handler, a component of a network layer of the protocol, wherein the network control protocol handler handles the servicing of at least one application variable by at least one of (A) handling by the network control protocol handler the persistence of a value of an application variable in storage, (B) providing by the network control protocol handler the value of a variable to a protocol layer other than the network layer through an application interface, (C) accepting by the network control protocol handler a new value of an application variable at the time a device is assigned to a logical network by an ASA, (D) accepting and acknowledging by the network control protocol handler a value of a new variable when instructed by the ASA and (E) providing a value of an application variable when asked by the ASA.

108. A distributed computing system according to claim 106, wherein the ASA updates the at least one application variable when a node is assigned to its logical network.

109. A distributed computing system according to claim 106, wherein the ASA broadcasts the at least one application variable to all nodes on the logical network through a Write message and each node acknowledges the message.

110. A distributed computing system according to claim 102, wherein the ASA unicasts Read and Write variable messages to verify and update a node.

111. A distributed computing system according to claim 98, wherein the altering of said at least one application variable is transparent to a layer other than a network layer of the protocol.

112. A distributed computing system according to claim 98, wherein said distributed system dynamically tunes and optimizes the protocol based upon a determination that a specific operating condition exists in the network.

113. A distributed computing system according to claim 112, wherein said specific operating condition includes at least one of (A) low bandwidth operation of the physical medium of the network, (B) potential noise (C) a dynamic determination that there is a weak transmitter node (D) a dynamic determination that there is a weak receptor node, (E) degraded signal quality on a communications path, (F) amount of activity on the network and (G) a specific combination of number and kinds of nodes.

114. A distributed computing system according to claim 113, wherein said at least one application variable includes at least one of (A) an adaptive back off parameter, (B) a timing window for network communications and (C) a threshold for a determination that there is at least one of said specific operating conditions.

115. A distributed computing system according to claim 98, wherein said distributed system cross-correlates with respect to the node segments of the network to determine which node paths are of good quality and which node paths are of poor quality.

116. A distributed computing system according to claim 115, wherein said cross-correlating includes taking into account the rate of network traffic.

117. A distributed computing system according to claim 98, wherein each node member of the logical network maintains a set of at least one value for at least one application variable associated with the node member.

118. A distributed computing system according to claim 117, wherein the set of values is handled by a network layer of the protocol, and saved in persisted storage.

119. A distributed computing system according to claim 98, wherein the at least one value is modified asynchronously.

120. A distributed computing system according to claim 98, wherein when at least one value of the at least one application variable is received, said at least one value is received through an application interface exposed by a network layer of the protocol.

121. A distributed computing system according to claim 120, wherein when at least one value of the at least one application variable is received with respect to a data link layer of said protocol, said at least one value of an application variable is received on every call to the application interface.

122. A distributed computing system according to claim 98, wherein the protocol is one of SCP, x10 and CEBus®

.

123. A distributed computing system according to claim 98, wherein a physical network underlying the logical network is one of a power line carrier network, a radio frequency network and an infrared transmission network.

124. A distributed computing system according to claim 98, wherein when application variables are altered, the distributed system ensures that the values are consistent across all nodes in the network.

125. A distributed computing system according to claim 98, wherein said at least one application variable at least one of (A) is set during a node acquisition step, (B) is set by default into one of a device and object and (C) is changed during optimization of the network dynamically.

126. A distributed computing system according to claim 98, wherein the at least one application variable comprises a variable length table maintained by the network layer.

127. A distributed computing system according to claim 98, wherein the at least one application variable is at least one of (A) logical network specific, (B) specific to a particular physical network underlying the logical network and (C) node specific.

128. A distributed computing system according to claim 98, wherein said at least one application variable is at least one protocol variable.

129. A distributed computing system according to claim 128, wherein at least one component of the distributed system sends a network control protocol read variables request message requesting reading of at least one protocol variable.

130. A distributed computing system according to claim 129, wherein at least one component of the distributed system sends a network control protocol read variables response message responding to a network control protocol read variables request message.

131. A distributed computing system according to claim 128, wherein at least one component of the distributed system sends a network control protocol write variables request message requesting writing of at least one protocol variable.

132. A distributed computing system according to claim 131, wherein at least one component of the distributed system sends a network control protocol write variables response message responding to a network control protocol write variables request message.

133. A distributed computing system according to claim 128, wherein at least one component of the distributed system receives a broadcast request message, whereby in response, replying nodes back off their reply up to a delay amount, defined by a delay application variable.

134. A distributed computing system according to claim 98, wherein a message is ignored if there is a threshold difference in time between a send time for the message and a receive time for the message.

135. A distributed computing system according to claim 98, further comprising:

a time master for assigning a network time to a message, wherein the network time is a unique number that is reset frequently to prevent replay attack.

136. A distributed computing system according to claim 135, wherein based on windowing, spoofing is protected against by jamming an imposter message.

137. A distributed computing system according to claim 98, wherein the presence of all other nodes on the network is tracked in accordance with said at least one application variable.

138. A logical network formed by a plurality of nodes comprising:

means for receiving at least one value for at least one application variable, the at least one application variable representative of a network tuning parameter for the logical network and the at least one application variable additionally corresponding to a network time synchronization application variable, wherein at least one node of the plurality of nodes is configured to use the at least one value to detect and ignore replay messages; and

means for altering at least one of protocol timing and network behavior relating to the at least one node of said plurality of nodes in said network based upon said at least one value.