Information Technology Reference
In-Depth Information
ATM Reference Model
Table 5-12
Layer or Plane Name
Description
User
Responsible for the transfer of video, voice, and data applications. The user
plane is associated with flow control and error recovery.
Management
Responsible for interaction between the user plane, control plane, and the
transport facilities.
Control
Responsible for call setup and maintenance, and call removal for SVCs.
Physical
Responsible for encoding the 53-byte cell on to the physical media. The
physical layer is composed of the transmission convergence (TC) sublayer
and the physical medium dependent (PMD) sublayer.
AT M
Responsible for creating cells. The ATM layer takes the 48-byte payload
from the AAL and appends a 5-byte cell header.
Adaptation
Responsible for adapting the information provided by the user plane to a
form that the ATM layer can use.
ATM Connection Types
Table 5-13
Layer or Plane Name
Description
VC
Virtual Channel (also known as virtual circuit). A VC switches cells based
on the tables in each switch. Connection tables identify the VPI/VCI and
interface for incoming and outgoing cells.
VP
Virtual path. A VP switches cells based on the VPI and interface for
incoming and outgoing cells.
SVC
A switched virtual circuit is created by UNI signaling from the attached
ES, such as a router.
PVC
A permanent virtual circuit is established manually and does not support
dynamic rerouting.
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