Routing controlled by subnet managers

Apparatus for communication, comprising:

• a plurality of routers interconnecting at least first and second subnets in a packet data network;
• and
• at least first and second subnet managers, which are operative to assign respective local identifiers to ports for addressing of data link traffic within each subnet, such that the first subnet manager assigns the local identifiers in the first subnet, and the second subnet manager assigns the local identifiers in the second subnet, to configure the routers by transmitting and receiving control traffic to and from the routers, and to control transmission of data packets between network nodes in the first and second subnets via one or more of the configured routers.

A computer software product, comprising a non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a computer in a first subnet of a packet data network that includes a plurality of routers interconnecting multiple subnets, cause the computer to function as a first subnet manager in the first subnet so as to assign respective local identifiers to ports for addressing of data link traffic within the first subnet, while at least a second subnet manager assigns the local identifiers to the ports in at least a second subnet,

• wherein the instructions cause at least the first and second subnet managers to configure the routers by transmitting and receiving control traffic to and from the routers, and to control transmission of data packets between network nodes in the first and second subnets via one or more of the configured routers.