Avaya M770 Manual Do Utilizador
Avaya M770 ATM Switch User’s Guide
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Appendix F
Routing and Signalling Concepts
This chapter describes how the Avaya M770 ATM Switch switches ATM cells
through an ATM network, and provides background information about the
concepts of routing and signalling.
through an ATM network, and provides background information about the
concepts of routing and signalling.
Switching ATM cells through the ATM network
There are two types of connection that can be used to switch ATM cells through an
ATM network.
•
ATM network.
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Permanent Virtual Circuits (PVCs), which are created manually by the network
administrator. Every switch through which the connection will pass will need
to be configured separately. PVCs are used for communication between two
endpoints, through a pre-configured circuit, until the administrator disables the
PVC and frees the connection.
administrator. Every switch through which the connection will pass will need
to be configured separately. PVCs are used for communication between two
endpoints, through a pre-configured circuit, until the administrator disables the
PVC and frees the connection.
•
Switched Virtual Circuits (SVCs), which are established on demand by UNI
(User-to-Network Interface)/NNI (Network-to-Network Interface) signalling
protocols. SVCs are used for communication between two endpoints until one
endpoint clears the connection. There are two types of SVCs:
— Point-to-point virtual circuits
— Point-to-multipoint virtual circuits.
(User-to-Network Interface)/NNI (Network-to-Network Interface) signalling
protocols. SVCs are used for communication between two endpoints until one
endpoint clears the connection. There are two types of SVCs:
— Point-to-point virtual circuits
— Point-to-multipoint virtual circuits.
In an ATM network, an end-station can establish a SVC to another end-station by
transmitting a signalling call setup request across the network. This request is
routed across the ATM network to the destination end-station. If the destination
agrees to accept the connection, a SVC is set up across the ATM network, between
the two end-stations.
transmitting a signalling call setup request across the network. This request is
routed across the ATM network to the destination end-station. If the destination
agrees to accept the connection, a SVC is set up across the ATM network, between
the two end-stations.
Virtual Circuits and Virtual Paths
In ATM networks data is multiplexed on physical links using virtual circuits and
virtual paths. A virtual circuit is a channel of communication that allows data
transfer between two ATM devices. A virtual path is used to group virtual circuits
within the same transmission medium so that they can be switched together. Virtual
circuits are identified by an unique Virtual Circuit Identifier (VCI). Virtual paths are
identified by an unique Virtual Path Identifier (VPI).
Figure C.1 shows how virtual circuits are bundled together within a virtual path.
virtual paths. A virtual circuit is a channel of communication that allows data
transfer between two ATM devices. A virtual path is used to group virtual circuits
within the same transmission medium so that they can be switched together. Virtual
circuits are identified by an unique Virtual Circuit Identifier (VCI). Virtual paths are
identified by an unique Virtual Path Identifier (VPI).
Figure C.1 shows how virtual circuits are bundled together within a virtual path.