IBM ATM OC-3c manual Multiplex, Octet, OC-n, Payload, Routing

4GLOSSARY

multiplex

In this user guide, multiplexing means to take packets from several sources and interleave them into one connection. For example, packets from data, voice, and video sources can be fed down one connection.

NNI

Network Node Interface — Sometimes known as Network-to-Network Interface.

OAM

Operations and Maintenance — A set of administration and supervisory actions regarding network performance monitoring, failure detection and system protection. Special type cells are used to carry OAM-related information.

Octet

8 bits or 1 byte.

OC-n

Optical Carrier-n — The physical interface for transmission over optical fiber at n times 51.84Mbps (for example, OC-3 is at 155.52Mbps, OC-12 at 622.08Mbps, OC-48 at 2.488Gbps).

Payload

Part of the ATM cell, it contains the actual information to be carried, and occupies 48 bytes. Also see PTI.

PTI

Payload Type Identifier — A 3-bit cell header field for encoding information regarding AAL and EFCI.

PVC

Permanent Virtual Circuit — A virtual connection established by network management between two points that is permanently available.

routing

A network management function responsible for forwarding packets from their source to their destination. A number of routing algorithms exist to suit different network topologies and requirements.

SAR

Segmentation and Reassembly — Partitions (segments) information frames into cells at the source and reassembles these cells back into information frames at the destination. These activities occur at the lower half of the AAL. It inserts the data from the information frames into the cell. It adds any necessary header or trailer bits to the data and passes the

48-octet to the ATM Layer. Each AAL type has its own SAR format. At the destination, the cell payload is extracted and converted to the appropriate information frame.

SDH

Synchronous Digital Hierarchy — A hierarchy that determines signal interfaces for very high speed digital transmission over optical fiber links.

SNMP

Simple Network Management Protocol — A standard defined for handling management information.