Abstract: There is disclosed a method for establishing a plurality of ATM adaption layer type 2 channels between interworking functions across a single ATM virtual channel connection. Within each interworking function there are a system management layer entity an ANP layer management identity and a protocol stack. The ANP layer management entities are further sub-divided into a series of functional blocks comprising: Originating procedures, Terminating procedures and Status Record entity. The Status Record entity records whether each AAL2 channel amongst the plurality of AAL2 channels is assigned/unassigned or activated/de-activated. A new AAL2 channel is established between interworking functions when a System Management entity sends in Assign—Request primitive to ANP layer management entity requesting an available AAL2 channel. The status record entity within ANP layer management entity is interrogated and an available AAL2 channel is identified.

Abstract: In a communications network, a virtual channel connection is established between first and second nodes in a communications network using a negotiating procedure to determine a mutually acceptable path identifier. The first node sends a connection request to the second node incorporating a path identifier for a virtual channel to be used for the connection. The second node determines whether the path identifier is acceptable for establishing the connection, and if so returns an acceptance message. If the path identifier is not acceptable to the second node, this node returns a negotiation request message incorporating a new path identifier for an alternative virtual channel to be used for the connection.

Abstract: There is disclosed a method for establishing a plurality of ATM adaption layer type 2 channels between interworking functions across a single ATM virtual channel connection. Within each interworking function there are a system management layer entity an ANP layer management identity and a protocol stack. The ANP layer management entities are further sub-divided into a series of functional blocks comprising: Originating procedures, Terminating procedures and Status Record entity. The Status Record entity records whether each AAL2 channel amongst the plurality of AAL2 channels is assigned/unassigned or activated/de-activated. A new AAL2 channel is established between interworking functions when a System Management entity sends in Assign_Request primitive to ANP layer management entity requesting an available AAL2 channel. The status record entity within ANP layer management entity is interrogated and an available AAL2 channel is identified.

Abstract: There is disclosed a method for establishing a plurality of ATM adaption layer type 2 channels between interworking functions across a single ATM virtual channel connection. Within each interworking function there are a system management layer entity an ANP layer management identity and a protocol stack. The ANP layer management entities are further sub-divided into a series of functional blocks comprising: Originating procedures, Terminating procedures and Status Record entity. The Status Record entity records whether each AAL2 channel amongst the plurality of AAL2 channels is assigned/unassigned or activated/de-activated. A new AAL2 channel is established between interworking functions when a System Management entity sends in Assign_Request primitive to ANP layer management entity requesting an available AAL2 channel. The status record entity within ANP layer management entity is interrogated and an available AAL2 channel is identified.

Abstract: The use of multiple AAL2 virtual circuits to support narrow band calls with multiple types of narrow band signalling systems leads to inefficient use of bandwidths over an ATM network. The present invention provides a method of transporting narrow band calls of multiple narrow band signalling type between narrow band networks across a single virtual circuit in an ATM network, where for each call connection within a circuit the call connection signalling information includes the narrow band signalling type.

Abstract: Collisions caused by simultaneous allocation of the same channel identifier (CID) to two AAL2 connections over an ATM virtual channel connection between first and second nodes in an asynchronous network are avoided by the use of status records. Each node maintains a record of currently assigned CIDs and compares the CIDs of incoming connection requests with that record. Where the CID of such an incoming request is found to have been assigned, a message is returned to the request originator refusing the connection request. Preferably a set of CIDs is assigned to one node so that, in the event of a potential collision, that node seizes the connection.

Abstract: The use of multiple AAL2 virtual circuits to support narrow band calls with multiple types of narrow band signalling systems leads to inefficient use of bandwidths over an ATM network. The present invention provides a method of transporting narrow band calls of multiple narrow band signalling type between narrow band networks across a single virtual circuit in an ATM network, where for each call connection within a circuit the call connection signalling information includes the narrow band signalling type.

Abstract: There is disclosed a method and a system for multiplexing data from a plurality of user data sources across an ATM adaption layer type-2 connection, in which a multiplexed trunk group extends across a plurality of common part sub-layer protocol data unit (CSU-PDU) mini-cells, and across a plurality of ATM cells. Large trunk groups are assembled by use of a single bit continuation indicator in the service specific convergence sub-layer header (SSCS) of successive CPS-PDU mini-cells. A packet payload type field (PPT) of the common part sub-layer (CPS)/service specific convergence sub-layer (SSCS) is used to indicate timing of changes in number of user data sources in a trunk group and provides for robust error recovery on loss of a single CPS-PDU mini-cell.

Abstract: In a communications system in which narrow band, e.g. voice, channels are carried in packet form over an asynchronous network, each channel is encoded to reduce its bit rate so as to reduce demands on band width. The encoding of each channel is effected via an algorithm selected from a group of algorithms associated with that channel. The algorithms forming the group are identified to a receiver station performing a decoding function via information provided in each packet header. The particular algorithm currently in use is determined implicitly from the packet length or from a combination of the packet length and a discriminator field provided in the packet header.

Abstract: Structured data traffic is transmitted from a first to a second narrow band network via first and second ATM networks having respective first and second adaptation layers, e.g. AAL1 and AAL2. The traffic is segmented on egress from the first ATM network is encapsulated for transport across the second ATM network so as to preserve the structure information of the data traffic. The narrow band networks may be time division multiplex networks.

Abstract: Telecommunications traffic is transported between first and second narrow band networks across an ATM network. Traffic from users of the first narrow band network is packetised into structured blocks within ATM cells. Each cell is provided with a respective control information field and with a header for routing the cells across the ATM network to the second narrow band network. The control information field incorporates a length indicator indicative of the size of the structured blocks within that cell whereby to control recovery of the user traffic from the cell.

Abstract: A system of the local area network (LAN) type using a closed loop optical fibre transmission medium, in which a series of stations, one of which acts as a master station, are connected to the loop. In each TDM cycle, a group of adjacent time slots is used as a framing group which occurs once per cycle of the system, the framing group including a multi-bit group number position which identifies a slot or group of slots. The loop includes a latency buffer to set the loop delay time to exactly 125 micro seconds, and the system according to the invention provides for both circuit-switched and packet-switched connections. To set up a circuit-switched connection, a free slot is chosen and its identity signaled in a packet manner. The proportion of slots allocated to circuit connections is varied dynamically, with indication thereof conveyed in a framing group of slots which occurs once in a cycle.