Abstract: A method ensures that multicast packets follow the same loop-free path followed by unicast packets in a packet communication network. The communication network includes at least one first area interconnected through at least one area border node (“ABN”) to a second area. Each ABN has a first level port connected to each first area and a second level port connected to the second area. Each multicast packet forwarded includes a header having a root-id identifying a root of a multicast tree. A data packet is received at an ABN. Responsive to receiving a multicast packet at a second level port of an area border node, the root-id of the multicast packet is examined and if the multicast packet is to be forwarded over at least one of the first level ports, a different root-id is substituted into the packet before the packet is forwarded over the first level port.

Abstract: A virtual private network infrastructure is provided which enables private network communications over a shared network. The infrastructure includes a shared network partitioned into at least two separate areas. A first router is connected to a first area and configured to distribute first router VPN information across the first area. The first router VPN information includes a VPN identifier which is assigned to the first router. It also includes a second router connected between the first area and a second area which is configured to distribute second router VPN information across the first area. The second router VPN information includes a VPN identifier which is assigned to the second router which is the same VPN identifier assigned to the first router. A method of configuring a virtual private network infrastructure is also provided which enables private network communications over a shared network.

Abstract: A virtual private network enables private communications between two or more private networks over a shared MPLS network. The virtual private network disclosed, includes multiple routers connected to the shared MPLS network and configured to dynamically distribute VPN information across the shared MPLS network. The VPN information distributed by a router includes a VPN identifier assigned to that router, which identifies a VPN with which that router is associated. The router includes a first table which stores a map of the label switched paths from the router in question to all other routers connected to the shared MPLS network. The router also includes a second table which stores a map of label switched paths from the router in question to all other routers connected to the shared MPLS network which share a common VPN identifier.

Abstract: The invention provides for a E-Mux and a method for encapsulating/segmenting ATM cells into/from an Ethernet frame at the boundary between an ATM and an Ethernet network. An Ethernet end-station on the E-Mux is addressed using multiple MAC level identifiers, which are dynamically assigned according to the ATM virtual circuits which terminate on that end station, and have only transitory significance on the Ethernet. A unique ATM OUI identifies the frames carrying ATM-traffic.

Abstract: In a hybrid fiber-coax distribution network, communications between a central station and particular end stations are encrypted using a working key (WK) of a symmetric encryption scheme. The central station has a public and private key (PPK) of a PPK encryption scheme, and some of the end stations can also each have a respective PPK. To provide secure communications for each end station, if the end station has a PPK, then the respective WK is generated in the central station and communicated, encrypted using the end station's public key (PK), to the end station. Otherwise, the WK is generated in the end station and communicated, encrypted using the central station's PK, to the central station. An individual identifier for each end station, and a cryptographic signature at least for end stations not having a PPK, can be communicated to the central station for authentication of the end stations.

Abstract: A distribution network groups television program signals into service tiers. To provide these from unsynchronized MPEG streams without resynchronization, each stream, representing a single program signal is encapsulated into ATM cells with a virtual path (VP) identification of each ATM cell corresponding to the service tier and a virtual channel (VC) identification corresponding to the respective program signal. Payloads in cells having the same VP are scrambled using a scrambling key allocated to that VP and hence to the corresponding service tier, and are unscrambled by entitled subscribers using the scrambling key which is supplied to them individually using public/private encryption techniques.

Abstract: The invention provides a ring communication network having an improved error recovery mechanism. The system uses a token or toggle signal which does not have an inherent control value but one that requires the values of a contiguous pair thereof to control access to the transmission medium of the system. A station recognizes that the ring is idle if the present value of the toggle signal is the same as the value of the toggle signal in the previous frame. Conversely, a station recognizes that the ring is busy if the present value of the toggle signal is different from the value of the toggle signal in the previous frame. A station that detects an idle toggle signal and wishes to transmit data on the communication ring changes the value of the toggle signal to that which corresponds to a busy status and transmits its data.