ATM Protocol
BRIM-A6 User’s Guide
Page B-5
B.3.2 PERMANENT AND SWITCHED VIRTUAL
CHANNELS
ATM networks use two different types of Virtual Channels – Permanent
Virtual Channels (PVCs) or Switched Virtual Channels (SVCs). The
difference between PVCs and SVCs exists in the channel set-up.
PVCs are pre-configured by an administration function, and are usually
established for long term use. After setting-up this channel, nothing else is
required by the network to transfer information between the two
established points. This type of virtual channelling is established through
a local or remote management interface.
SVCs use a signaling and network switching procedure to set up
dynamically. In other words, SVCs establish “on the fly,” as needed for a
particular service, are used to transmit on the short term, and then
terminated. Each time a specific channel is established, a routing protocol
comes into play providing LAN-style operation and management.
B.4 ATM PROTOCOL
Existing PTM transmission technologies (Ethernet, Token Ring, FDDI)
adhere to the International Organization for Standardization (ISO) Open
System Interconnection (OSI) model. This seven layer model provides a
consistent hierarchy of rules for developing system connection standards.
In essence, OSI is a framework on which protocols for particular network
types are based. It is important to note that the OSI model is different
from the ATM model.
A user’s perception of how a network operates is that it provides a direct
link to another device. In reality, the information that the user sees is
routed through the layers represented in the following models. Each layer
modifies the information a user is either sending or receiving, according
to the standards or protocol established for each individual layer.
book Page 5 Thursday, April 18, 1996 2:18 PM
Summary of Contents for BRIM-A6
Page 1: ...BRIM A6 USER S GUIDE...
