Message sequencing for ordered multicasting of a message across a routing network

This invention relates in general to multicasting messages within a network and, in particular, to sequencing messages within a routing network to facilitate ordered delivery thereof to one or more clients. A technique for reliably multicasting a message within a router network in a sequenced order with other messages is provided. At least one special router in the network has associated persistent storage for sequencing a message being routed to one or more clients. When a message is received at this sequencer node, the sequencer places a sequence number for the message in persistent storage and sends a sequencing acknowledgment back to those routers to which the message was originally routed, as well as back towards the source of the message. The sequencer acknowledgment includes the message id, and the sequencing number. When the sequencer acknowledgment is received by a router, it looks up the routing information from the original message, and sends the acknowledgment to those neighboring routers to which the original message was sent, excluding the link from which the sequencer acknowledgment was received. If the original message corresponding to the sequencer acknowledgment was buffered at this router waiting to be delivered, the message is then delivered to its client nodes.