Nortel Networks Corporation

Allen Houston

Christopher David Murton

Paul Fee

Philip Christian

Terence Canning

Derek Gilmore

Ewart Tempest

In the preferred embodiment, the invention provides a modified Shortest Path First routing algorithm for use in a heterogeneous network. The routing algorithm is modified to include predetermined heterogeneous characteristics of the network nodes and to take these characteristics into account when calculating the shortest paths. For example, information may be included in the algorithm which identifies heterogeneous network nodes as it calculates shortest paths. Once a node has been identified as heterogeneous, i.e., capable of supporting at least two protocol sets, this information is carried over into subsequent path entries created by the routing algorithm. The algorithm then uses the encapsulation capability identifier in the calculation of the shortest paths by including the cost of auto-tunneling between heterogeneous nodes to be taken into account when determining the short path.

Routing method and apparatus for optimising auto-tunnelling in a heterogeneous network

The present invention relates to data tunnelling and in one embodiment to the tunnelling of IP (Internet Protocol) data across an OSI (Open Systems Interconnect) network. In the preferred embodiment, network elements include both an OSI stack and an IP stack, and a respective directory of OSI addresses and corresponding IP subnets. Each network element generates a routing data packet, conveniently a Link State Packet (LSP), which includes the OSI address and IP subnet(s) associated with that network element. The LSPs are distributed across the network in normal manner. Upon receipt of an LSP from another network element, each network element updates its respective directory in respect of said other network element. Thus, each directory is automatically updated to reflect changes in the network, particularly in respect of IP subnets. This arrangement significantly reduces the need for manual tunnel configuration in the network. In an alternative embodiment, the invention provides dynamic data tunnelling of OSI data over an IP network.

Dynamic data tunnelling

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Antrim, United Kingdom

Allen Houston