Hybrid units for a communication network
First Claim
1. A communication network comprising:
- end units (EUs) and distribution units (DUs) coupled together by communication links, each end unit having one or more network service access points (NSAP) 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 EU-Hello and DU-Hello messages which indicate whether the sender is either an end unit or a distribution unit, and the EU-Hello and DU-Hello messages containing the NSAP(s) of the end units and distribution units, the DUs collectively maintaining complete information about all NSAPs; and
a hybrid unit (HU) having one HUE link and a plurality of HUD links, said HUE link coupled with one of said distribution units, each one of said HUD links coupled with one of said end units, said hybrid unit sending on the HUE link EU-Hello messages containing the NSAPs of all EUs from which it receives EU-Hello messages on its HUD links, and sending on the HUD links DU-Hello messages.
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Abstract
A communication network consists of end units (EUs) and distribution units (DUs) coupled together by links which may include local area networks (LANs). The units maintain neighbor tables by sending out Hello messages which indicate the unit type and contain the network service access point (NSAP) IDs or addresses of the units. Data messages (packets) mainly originate and end at EUs. An EU maintains only partial routing information about neighbors, while the DUs collectively maintain complete information about all NSAPs. So if an EU wants to send a packet to an EU which is not a neighbour (and sometimes even if it is), it need merely send it to a neighboring DU; that DU, along with the other DUs, must find a route to the destination EU. This invention provides a hybrid unit (HU), which acts as a DU to EUs but as an EU to DUs. The HU provides DU-like message forwarding but only on a local basis within a subnetwork of EUs and HUs.
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Citations
23 Claims
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1. A communication network comprising:
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end units (EUs) and distribution units (DUs) coupled together by communication links, each end unit having one or more network service access points (NSAP) 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 EU-Hello and DU-Hello messages which indicate whether the sender is either an end unit or a distribution unit, and the EU-Hello and DU-Hello messages containing the NSAP(s) of the end units and distribution units, the DUs collectively maintaining complete information about all NSAPs; and a hybrid unit (HU) having one HUE link and a plurality of HUD links, said HUE link coupled with one of said distribution units, each one of said HUD links coupled with one of said end units, said hybrid unit sending on the HUE link EU-Hello messages containing the NSAPs of all EUs from which it receives EU-Hello messages on its HUD links, and sending on the HUD links DU-Hello messages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A communication network comprising:
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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. - View Dependent Claims (12, 13)
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14. A communication network comprising:
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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. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification