Atm Connectivity; Overview - Alcatel speed touch home Advanced User's Manual

14 Advanced Networking Concepts

14.1 ATM Connectivity

14.1.1

Overview

Virtual Channels
Channel Identifiers
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All data arriving at, and departing from, your Speed Touch
Home via the ADSL Line is carried in ATM cells.
ATM is a connection oriented packet switching technology using
fixed size packets, called cells. These cells consist of a header and
a payload and are switched through a public or private ATM
network depending on the contents of the header. End to end
connections are formed by cross connecting individual ATM
segments in ATM switches.
ATM uses Virtual Channels (VC)(s) to create individual
communication links between network nodes. ATM uses two types
of VCs:
Permanent Virtual Channels (PVC)(s) are static connections
"
between network nodes that are configured statically.
The nodes of the connection operate as if they were
connected by a dedicated physical line.
Switched Virtual Channels (SVC)(s) are similar to voice
"
telephone network connections. These are temporary
connections between any two end points on the network and
are configured via signaling. SVCs are created dynamically
for each session and released when the information exchange
is complete.
Currently all STHome ATM connections are static , i.e. PVCs.
Each ATM cell carries two labels, VPI and VCI as part of its header.
An ATM channel, commonly referred to as virtual channel, is fully
identified by these two labels. Therefore, multiple ATM channels
can reside on your ADSL line.
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