Method and apparatus for reducing jitter accumulation in a series of repeating devices

An apparatus for reducing jitter in a data stream transmission along a physical communication channel, the data stream accumulating jitter during retransmission along a series of repeating devices, the data stream entering the series of repeating devices as an entry data stream, the data stream exiting from the series of repeating devices as an exit data stream, the apparatus comprising:

• means for receiving the exit data stream from the series of repeating devices;
• means for storing said exit data stream;
• means for recovering a clock signal of the entry data stream;
• and
• means for outputting the exit data stream as a jitter-reduced data stream at a timing rate defined by the recovered clock signal.

A method for reducing jitter in a data stream transmission along a physical communication channel in a token ring network, the token ring network having a plurality of station groups, each group having a plurality of stations, the data stream accumulating jitter during retransmission along a series of stations in a first group of said plurality of groups, the data stream entering the first group as an entry data stream, the data stream exiting from the first group as an exit data stream, the method comprising the steps of:

• receiving the exit data stream from a station;
• storing said exit data stream;
• selecting one data stream from said entry data stream or said exit data stream;
• recovering a clock signal of said selected one data stream;
• and
• outputting the exit data stream as a jitter-reduced data stream at a timing defined by the recovered clock signal.

A token ring network having a plurality of groups of stations, a first group of stations receiving an entry data stream and outputting an exit data stream, the network comprising:

• means for selecting one data stream from said entry data stream or said exit data stream as a source for recovering a clock signal;
• means for recovering a clock signal of said selected one data stream;
• and
• means receiving said exit data stream for reducing jitter accumulating during transmissions along said first group of stations, said jitter reducing means outputting the exit data stream as a jitter-reduced data stream at a timing defined by the recovered clock signal.

A method for determining whether an active monitor is present among a plurality of stations along a token ring network, the first group receiving an entry data stream and outputting an exit data stream, the method comprising the steps of:

• storing a first source address of an exit data stream which serves as a claim token frame;
• comparing a second source address of a subsequent entry data stream which also serves as a claim token frame with said first source address;
• and
• indicating that said plurality of stations includes the active monitor when said second source address changes to equal said first source address.

A method for reducing jitter in a data stream transmission along a physical communication channel in a token ring network, the token ring network having a plurality of station groups, each group having a plurality of stations, the data stream accumulating jitter during retransmission along a series of stations in a first group of said plurality of groups, the data stream entering the first group as an entry data stream, the data stream exiting from the first group as an exit data stream, the method comprising the steps of:

• receiving the exit data stream from a station;
• storing said exit data stream;
• selecting one data stream from said entry data stream or said exit data stream;
• recovering a clock signal of said selected one data stream;
• outputting the exit data stream as a jitter-reduced data stream at a timing defined by the recovered clock signal;
• and
• monitoring the entry data stream and exit data stream to determine whether the first group includes an active monitor station, and in which the step of selecting includes an active monitor selecting said entry data stream when said first group does not include an active monitor.

A token ring network having a plurality of groups of stations, a first group of stations receiving an entry data stream and outputting an exit data stream, the network comprising:

• means for selecting one data stream from said entry data stream or said exit data stream as a source for recovering a clock signal;
• means for recovering a clock signal of said selected one data stream;
• means receiving said exit data stream for reducing Jitter accumulating during transmissions along said first group of stations, said jitter reducing means outputting the exit data stream as a jitter-reduced data stream at a timing defined by the recovered clock signal;
• and
• means for monitoring the entry data stream and exit data stream to determine whether the first group includes an active monitor station, and in which the means for selecting selects the exit data stream as the source for the recovered clock signal when said first group does not include an active monitor.