Hybrid units for a communication network

A communication network comprising:

• End Units and Distribution Units coupled together by communication links, each End Unit having one or more Network Service Access Points, and each Distribution Unit including routing tables for routing data packets through the network between End Units, the End Units and Distribution Units maintaining knowledge of their neighboring End Units and Distribution Units by exchanging End Unit Hello and Distribution Unit Hello messages which indicate whether the sender is either an End Unit or a Distribution Unit, and the End Unit Hello and Distribution Unit Hello messages containing the Network Service Access Points of the End Units and Distribution Units, the Distribution Units collectively maintaining information about all Network Service Access Points;
• and
• a Hybrid Unit having one link behaving as an End Unit Link and coupled with one of said Distribution Units, and a plurality of links behaving as Distribution Unit Links, each one of said plurality of links behaving as Distribution Unit links coupled with one of said End Units, said Hybrid Unit sending End Unit Hello messages on said link behaving as an End Unit Link, said End Unit Hello messages containing the Network Service Access Points of all End Units from which said Hybrid Unit receives End Unit Hello messages on said plurality of links behaving as Distribution Unit Links, and said Hybrid Unit sending Distribution Unit Hello messages on said plurality of links behaving as Distribution Unit links.

A communication network comprising:

• a plurality of communication links;
• one or more End Units, each of said one or more End Units coupled with one of said plurality of communications links, each one of said one or more End Units having one or more Network Service Access Points, each one of said one or more End Units transmitting End Unit Hello Messages containing said one or more Network Service Access Points, and receiving End Unit Hello Messages and Distribution Unit Hello Messages, each one of said End Units maintaining knowledge of those of said one or more End Units and those of one or more Distribution Units that are neighbors to said one of said End Units;
• each one of said one or more Distribution Units coupled with one of said plurality of communication links, each one of said one or more Distribution Units having routing tables for routing packets through said communications network between said one or more End Units, each one of said one or more Distribution Units transmitting Distribution Unit Hello Messages and receiving End Unit Hello Messages and Distribution Unit Hello Messages, each one of said one or more Distribution Units maintaining knowledge of those of said one or more End Units and said one or more Distribution Units that are neighbors of said one of said one or more Distribution Units, and said one or more Distribution Units collectively maintaining information about all Network Service Access Points;
• and
• a Hybrid Unit having one End Unit link and a plurality of Distribution Unit links, said End Unit link coupled with one of said one or more Distribution Units, each one of said Distribution Unit links coupled with one of said one or more End Units, said hybrid unit sending EU-Hello messages onto said End Unit link, said EU-Hello messages containing the NSAPs of all End Units from which said Hybrid Unit receives EU-Hello messages on said plurality of Distribution Unit links, and said Hybrid Unit sending DU-Hello messages onto said plurality of Distribution Unit links.