Link advertisement for path computation in a communications network

A method of generating a link advertisement at a hybrid node of a network, the hybrid node comprising switching matrices operable using different protocols and two or more internal links between the switching matrices, the internal links operable to pass a traffic flow between the first and second switching matrices and to adapt the traffic flow to suit the protocols of the switching matrices, the method comprising:

• determining, for each of the two or more internal links, a maximum bandwidth available for a single new traffic flow and a minimum bandwidth allocable for a single new traffic flow;
• determining, based on the minimum and maximum bandwidths for each of the two or more internal links, an overall maximum bandwidth on any one of the two or more internal links available for a single new traffic flow and an overall minimum bandwidth allocable on any one of the two or more internal inks for a single new traffic flow;
• generating a link advertisement comprising the overall maximum bandwidth available for a single new traffic flow on any one of the internal links, and the overall minimum bandwidth allocable to such a new traffic flow;
• and
• sending the link advertisement to another part of the network.

A path computation element for a communications network, the path computation element comprising:

• an interface operable to receive link advertisements from nodes of the communications network;
• and
• a processor operable to:
• select paths for new traffic flows based on the received link advertisements, wherein at least one of the nodes is a hybrid node having switching matrices operable using different protocols, and having two or more internal links between the switching matrices, the link advertisements received from the hybrid node comprising overall maximum and overall minimum bandwidths on any one of the internal links for a new traffic flow, wherein:
• the overall maximum bandwidth represents a maximum bandwidth from a set comprising maximum bandwidths available for a single new traffic flow for each of the two or more internal links;
• and
• the overall minimum bandwidth represents a minimum bandwidth from a set comprising minimum bandwidths allocable for a single new traffic flow for each of the two or more internal links;
• and
• select a path via the hybrid node for a new traffic flow according to the bandwidth of the requested new traffic flow and according to the overall maximum and overall minimum bandwidths of the link advertisements.

A method of operating a path computation element, the method comprising:

• receiving a link advertisement from a hybrid node of a communications network, the hybrid node comprising switching matrices operable using different protocols, and comprising two or more internal links between the switching matrices, the link advertisements received from the hybrid node comprising overall maximum and overall minimum bandwidths on any one of the internal links for a new traffic flow wherein:
• the overall maximum bandwidth represents a maximum bandwidth from a set comprising maximum bandwidths available for a single new traffic flow for each of the two or more internal links;
• and
• the overall minimum bandwidth represents a minimum bandwidth from a set comprising minimum bandwidths allocable for a single new traffic flow for each of the two or more internal links;
• and
• selecting a path for a new traffic flow based on the received link advertisements, such that a path via the hybrid node is selected according to a bandwidth of the requested new traffic flow and according to the overall maximum and overall minimum bandwidths of the link advertisement.

A node for a communications network, the node comprising:

• a plurality of external connections interconnected by a first switching matrix and operable according to a first protocol;
• a plurality of external connections interconnected by a second switching matrix and operable according to a second protocol;
• at least two internal links between the first and second switching matrices, each of the internal links being operable to pass a traffic flow between the first and second switching matrices and to adapt the traffic flow to suit the protocols of the switching matrices;
• and
• a controller operable to:
• determine, for each of the at least two internal links, a maximum protected bandwidth available for a single new traffic flow;
• determine a maximum aggregate protected bandwidth of all the internal links by aggregating the determined maximum protected bandwidths for each of the at least two internal links;
• and
• generate and send to another part of the network a link advertisement comprising the maximum aggregate protected bandwidth available for new traffic flows on all of the internal links.

A node for a communications network, the node comprising:

• a plurality of external connections interconnected by a first switching matrix and operable according to a first protocol;
• a plurality of external connections interconnected by a second switching matrix and operable according to a second protocol;
• at least two internal links between the first and second switching matrices, each of the internal links operable to pass a traffic flow between the first and second switching matrices and to adapt the traffic flow to suit the protocols of the switching matrices;
• and
• a controller operable to:
• determine, for each of the at least two internal links, a maximum bandwidth available for a single new traffic flow;
• determine a maximum aggregate bandwidth of all the internal links by aggregating the determined maximum bandwidths for each of the at least two internal links;
• and
• generate and send to another part of the network a link advertisement comprising the maximum aggregate bandwidth of all the internal links.