Nortel Passport 4400 Series Introduction Manual page 134

Passport 4400 Introduction and Road Map
External Line Loopback Test
FECN (Forward Explicit Congestion Notification)
Filters
Frame
FP (Function Processor)
FRS (Frame Relay Service)
HDB3
Glossary-8
Also known as the Line Loopback test. Similar to the External Digital
Loopback test, except that it does not test the unframing and framing
circuits.
The FECN bit is used in the Frame Relay header of a frame to warn the
receiving-end device that the frames it is receiving (traveling in the
same direction) have encountered congestion or congested resources.
A process or device that screens network traffic for certain
characteristics, such as source address, destination address, or protocol,
and determines whether to forward or discard that traffic based on the
established criteria.
See T1 frame and E1 frame
A type of processor card for the Passport 6400 that supports physical
interface connections to subscriber lines and network trunks. It is
optimized to support the software that performs the real-time functions
associated with the forwarding and routing of frames. Different types of
FPs support different types of physical interfaces, such as DS1, E1, V.35,
and V.11 access and trunks. See also Control and Function Processor.
A streamlined ISO data link layer protocol. A frame relay network
supports only core communications functions (such as transparency,
multiplexing, and orderly delivery). This simplified processing (as
opposed to traditional packet data protocols) permits higher speeds and
lower delays for a given processing capability.
Simplification is made possible by the assumed use of improved
transmission facilities (high quality digital facilities), which are affected
by fewer transmission errors. Many functions such as sequencing flow
control and retransmission are performed by the end-user equipment.
A zero suppression coding method used in E1 transmission systems. It
limits the maximum number of consecutive zeros to three. Any four
consecutive zeros are replaced with a pattern that includes a bipolar
violation. See B8ZS.
Glossary