Planning routes and allocating identifiers to routes in a managed frame-forwarding network

A machine-readable medium carrying instructions for causing a processor to perform a method of planning routes and allocating route identifiers in a managed frame-forwarding network, the network comprising a plurality of nodes interconnected by links, with each node being arranged to forward data frames according to a combination of a route identifier and a network address carried by a received data frame and forwarding instructions stored at the node, the method comprising:

• identifying a sub-set of the nodes which are core nodes of the network. the remaining nodes being outlying nodes;
• building a spanning tree off each of the identified core nodes, with the spanning tree stopping one link short of any other core node, the spanning tree defining a loop-free path between a core node at the root of the spanning tree and a set of outlying nodes;
• and,
• planning connections between roots of the spanning trees and allocating a different route identifier to each planned connection between a pair of spanning trees.

A managed frame-forwarding network comprising:

• a set of nodes interconnected by links, with each node being arranged to forward data frames according to a combination of an identifier and a network address carried by a received data frame and forwarding instructions stored at the node;
• a network planning entity for planning routes and for allocating route identifiers to routes within the network, the entity being arranged to:
• identify a sub-set of the nodes which are core nodes of the network, the remaining nodes being outlying nodes;
• build a spanning tree off each of the identified core nodes, with the spanning tree stopping one link short of any other core node, the spanning tree defining a loop-free path between the core node at the root of the spanning tree and a set of outlying nodes;
• and,
• plan connections between roots of the spanning trees and allocate a different route identifier to each planned connection between a pair of spanning trees
• a connection controller which is arranged to generate forwarding instructions to cause the nodes to implement the routes planned by the network planning entity.