Nortel Networks 8000 - Manual (Page 35)

Nortel Secure Router 8000 Series
Configuration -WAN Access 1 WAN access overview
Frame relay
HDLC
ATM
PPPoE
Describes how to create virtual circuits, forward packets, create links, transport data,
disconnect links, and disconnect virtual circuits between DTE and DCE.
Performs error control, tragic control and instance statistics, providing users with
optional service functions and configuration functions.
Provides a bit-oriented protocol to implement data link control, which is called Link
Access Procedure, Balanced (LAPB).
Frame Relay (FR) is a technology developed in the early 1980s. It is derived from X.25
packet communication technology.
Data transfer in the form of frames with a set of procedures uses frame relay. Frame relay
implements logical rather than physical connections. Multiple logical connections can be
multiplexed onto the same physical connection. The multiple logical channels can thus be
created to achieve bandwidth multiplexing and dynamic allocation.
FR simplifies X.25. It has high processing efficiency, high network throughput, and low delay.
High-Level Data Link Control (HDLC) is a group of protocols used for data transmission.
HDLC is one of the most widely applied protocols on the data link layer.
HDLC data units (frames) transmit through the network and the receiver acknowledges.
HDLC also manages data flow and data sending intervals.
Asynchronous Transfer Mode (ATM) takes a cell as the basic unit for implementing
information transportation, multiplexing, and exchange. ATM cells come from different
sources without any special mode requirement. Idle cells fill the spaces between cells.
An ATM link is the unidirectional transmission mode and supports multiple rates that are
compatible with SONET. The transfer medium of ATM is generally optical fiber. ATM also
uses coaxial cable or a category 5 twisted pair within 100 m for cable television Hybrid Fiber
Coaxial Network (HFC).
Point-to-Point Protocol over Ethernet (PPPoE) constructs multiple hosts into a network over
the ethernet, accesses the internet through a remote access device, and implements control and
accounting on the host that it accesses.
Community network construction uses PPPoE with high-performance ratio.
Issue 5.3 (30 March 2009) Nortel Networks Inc. 1-5