Abstract: A method for responding to a failure of hardware locus of at a communication installation having a plurality of control apparatuses for controlling a plurality of processes distributed among a plurality of hardware loci, the hardware loci including at least one spare hardware locus, includes the steps of: (a) Shifting control of a failed process from an initial control apparatus to an alternate control apparatus located at an alternate hardware locus than the failed hardware locus. The failed process is a respective process controlled by the initial control apparatus located at the failed hardware locus. (b) Relocating the respective control apparatuses located at the failed hardware locus to a spare hardware locus. (c) Shifting control of the failed process from the alternate control apparatus to the initial control apparatus relocated at the spare hardware locus.

Abstract: Multicast capabilities of a link state protocol controlled network are used to accelerate the flooding advertisement of topology change notifications within portions of the network. This flooding mechanism may be particularly efficient in a network with a large number of two-connected nodes such as a ring network architecture. A control plane specific multicast group address is used when flooding topology change notifications, and a process such as reverse path forwarding check is used as an additional control on forwarding of the notification to prevent looping of control plane packets. Two-connected nodes insert a forwarding entry into their FIB to enable frames containing the control message to be forwarded via the data plane on to the downstream node so that propagation of the control message along a chain of two-connected nodes may occur at data plane speeds.

Abstract: Routes may be installed across multiple link state protocol controlled Ethernet network areas by causing ABBs to leak I-SID information advertised by BEBs in a L1 network area into an L2 network area. ABBs will only leak I-SIDs for BEBs where it is the closest ABB for that BEB. Where another ABB on the L2 network also leaks the same I-SID into the L2 network area from another L1 network area, the I-SID is of multi-area interest. ABBs will advertise I-SIDs that are common to the L1 and L2 networks back into their respective L1 network. Within each L1 and L2 network area, forwarding state will be installed between network elements advertising common interest in an ISID, so that multi-area paths may be created to span the L1/L2/L1 network areas. The L1/L2/L1 network structure may recurse an arbitrary number of times.