Systems and methods of measuring latency and routing thereon in optical networks
The present disclosure provides systems and methods for making latency measurements and using these measurements in routing in optical networks. In an exemplary embodiment, a method is defined whereby two nodes sharing a line automatically determine whether both nodes are capable of making a latency measurement and then which node will initiate and which node participates in making the latency measurement. In another exemplary embodiment, an on-demand latency measurement may be made between any two arbitrary nodes within a domain. Routing messages may be used to disseminate the latency of links via a signaling and routing protocol. Advantageously, the present invention provides measurement of latency and latency variation of customer circuits (i.e., SNCs) using an in-band, non-intrusive calculation with a high-degree of accuracy. Furthermore, the present invention may consider these calculations for circuit routing based on the latency and circuit acceptance based on maximum latency restrictions.
1. An optical network, comprising:
a plurality of optical nodes;
a plurality of links interconnecting the plurality of optical nodes; and
wherein a first node of the plurality of optical nodes is configured to initiate a latency measurement to a second node of the plurality of optical nodes via transmitting an indicator using a signaling and routing protocol, the second node configured to receive and loop-back the indicator to the first node, and the first node configured to calculate latency to the second node based upon reception of the loop-backed indicator; and
wherein the first node is configured to calculate latency by adding latencies associated with each of the plurality of links between the first node and the second node plus a predetermined latency time for each pass-through node.
2. The optical network of claim 1 , wherein the indicator comprises transitioning one or more bits in overhead.
3. The optical network of claim 2 , wherein the overhead comprises Synchronous Optical Network or Synchronous Digital Hierarchy.
4. The optical network of claim 2 , wherein the overhead comprises Optical Transport Network.
5. The optical network of claim 1 , wherein the first node is configured to perform a plurality of latency measurements to the second node and computing an average of the plurality of latency measurements.
6. The optical network of claim 5 , wherein, if the plurality of latency measurements differs by more than one frame, then the first node indicates inability to obtain a stable latency measurement.
7. The optical network of claim 1 , further comprising:
a management system communicatively coupled to the plurality of nodes;
wherein the management system is configured to execute an on-demand latency measurement between any arbitrary points of the plurality of nodes with the first node and the second node selected through the management system.
8. The optical network of claim 7 , wherein the on-demand latency measurement comprises:
determining a designated transit list between the first node and the second node; and
utilizing an active sub network connection on the designated transit list for the indicator to measure latency at the first node.
9. The optical network of claim 8 , wherein the on-demand latency measurement further comprises:
if there is no active sub network connection on the designated transit list, creating an on-demand sub network connection to measure latency at the first node; and
deleting the on-demand sub network connection following measurement.
10. The optical network of claim 1 , further comprising:
a controller disposed at the first node and the second node, wherein the controller is configured to operate a signaling and routing protocol to provision sub network connections between the first node and the second node;
wherein the controller is configured to transmit and receive measured or manually entered latencies associated with the plurality of links via messages in the signaling and routing protocol; and
wherein the controller is configured to utilized the latencies in route selection of the sub network connections.
11. The optical network of claim 10 , wherein the controller is configured to route the sub network connections between the first node and the second node to ensure that the total latency from the first node to the second node is less than the maximum latency specified for the sub network connection.
12. A method, comprising:
operating an optical network comprising a plurality of nodes and a signaling and routing protocol;
utilizing a latency measurement algorithm to measure latency on a plurality of links interconnecting the plurality of nodes using the signaling and routing protocol;
distributing measured latency values on the plurality of links via messages in the signaling and routing protocol;
storing the measured latency values in a database;
utilizing the measured latency values in the signaling and routing protocol for route selection;
requesting a sub network connection between two nodes of the plurality of nodes;
requesting a maximum latency value for the sub network connection; and
determining a designated transit list based on the maximum latency value and the measured latency values.
13. The method of claim 12 , wherein the latency measurement algorithm comprises:
determining a master node and a slave node of the plurality of nodes, wherein the master node and the slave node are adjacent to one another connected by a link of the plurality of links;
transmitting an indicator from the master node to the slave node;
looping back the indicator at the slave node to the master node;
receiving the looped back indicator at the master node and computing a latency value; and
repeating the transmitting, looping back, and receiving steps a plurality of times to provide an averaged latency measurement as the measured latency value of the link.
14. The method of claim 13 , wherein master node and the slave node are determined based upon node identification values.
15. A latency measurement method, comprising:
operating a plurality of optical nodes in a domain, wherein the plurality of optical nodes are communicatively coupled to a management system;
selecting two arbitrary nodes defined as an initiator node and a terminator node of the plurality of optical nodes for computing latency therebetween using a signaling and routing protocol;
selecting a designated transit list between the two arbitrary nodes;
transmitting an indicator in an active sub network connection using the designated transit list to the terminator node from the initiator node;
looping back the indicator at the terminator node to the initiator node; and
receiving the indicator at the indicator node and computing latency based upon a time interval from transmitting the indicator until the receiving the indicator divided by two.
16. The latency measurement method of claim 15 , further comprising:
if no active sub network connection exists using the designated transit list, creating an on-demand sub network connection using the designated transit list thereby providing the active sub network connection; and
deleting the on-demand sub network connection upon completion.
17. The latency measurement method of claim 15 , further comprising:
locking the active sub network connection prior to the transmitting step thereby preventing mesh restoration; and
unlocking the active sub network connection upon completion.