Node and system for a synchronous network

A method performed by a first node in a synchronous network, the synchronous network including a plurality of nodes, each node being interconnected via an interface to at least one neighboring second node of the plurality of nodes over an isochronous transport link for transmission and reception of repetitive frames comprising user data, the method comprising:

• using an interface of the first node, transmitting and receiving to and from the second node repetitive frames comprising user data,
• establishing a first local time of the first node using a first local clock,
• synchronizing the first local time to a time established by a second local clock of the second node,
• wherein the synchronizing comprises phase locking the first local clock to a time difference between the first local clock and the second local clock, and
• exchanging, via the interface, time information of the first node and the second node by way of the repetitive frames,
• wherein the time difference is determined by
• receiving a first timestamp of the second local clock,
• providing a first time difference between (i) the first local time at reception of the first timestamp and (ii) the received first timestamp,
• transmitting a second timestamp of the first local time to the second node, and
• receiving from the second node a second time difference between (i) the second local time at reception of the second timestamp and (ii) the second timestamp.

A method for a synchronous network including a plurality of nodes, the plurality of nodes being interconnected over isochronous transport links, the method comprising:

• adapting a network synchronization topology, and
• synchronizing local clocks of the plurality of nodes to a local clock of a master node by bidirectional exchange of time information by way of repetitive frames comprising user data over the isochronous transport links,
• wherein the time information includes time differences between times kept by the local clocks, and for each node of the plurality of nodes,
• using an interface of the node, transmitting and receiving to and from a neighboring node repetitive frames comprising user data, establishing a first local time of the node using a first local clock,
• synchronizing the first local time to a time established by a second local clock of the neighboring node,
• wherein the synchronizing comprises phase locking the first local clock to a time difference between the first local clock and the second local clock, and
• exchanging, via the interface, time information of the node and the neighboring node by way of the repetitive frames,
• wherein the time difference is determined by
• receiving a first timestamp of the second local clock,
• providing a first time difference between (i) the first local time at reception of the first timestamp and (ii) the received first timestamp,
• transmitting a second timestamp of the first local time to the neighboring node, and
• receiving from the neighboring node a second time difference between (i) the second local time at reception of the second timestamp and (ii) the second timestamp.

A synchronous network comprising:

• a first node;
• and
• a second node that is connected to the first node over an isochronous transport link for transmission and reception of repetitive frames comprising user data, wherein:
• the first node establishes a first local time using a first local clock;
• the second node establishes a second local time using a second local clock;
• the first node synchronizes the first local time to the second local time by phase locking the first local clock to a time difference between the first local clock and the second local clock;
• the time difference is determined by
• receiving a first timestamp of the second local clock,
• providing a first time difference between (i) the first local time at reception of the first timestamp and (ii) the received first timestamp,
• transmitting a second timestamp of the first local time to the second node, and
• receiving from the second node a second time difference between (i) the second local time at reception of the second timestamp and (ii) the second timestamp;
• and
• time information of the first node and the second node is exchanged between the first and second nodes by way of the repetitive frames.