Glossary of Terminology - WAN-EXPAND/TRAFFIC SHAPING


Traffic Shaping-a form of bandwidth management that combines several QoS capabilities: buffering, congestion detection, avoidance, and rate limiting.

SLA-Service Level Agreement-Contractual agreement of network performance criteria between a service provider and the customer.

Traffic-The load on a communications device or system.

Circuit-Term used to describe many types of communication transport types whether Frame Relay, Internet, DSL, ISDN, Dial Up Line, ATM, T1, Fractional T1, Satellite.

Quality of Service (QoS)-A set of metrics used to measure the quality of transmission and service availability of any given transmission system.

T1 Circuit-1.544MB of bandwidth.

OSI Reference Model-Open Systems Interconnection reference model: A conceptual
Model defined by the International Standardization Organization (ISO), describing how any combination of devices can be connected for the purpose of communication. The OSI model divides the task into seven functional layers, forming a hierarchy with the applications at the top and the physical medium at the bottom, and it defines the functions each layer must provide.

Physical layer: Layer 1 of the OSI reference model. It is responsible for converting data packets from the Data Link Layer into electronic signals.

Data Link Layer: layer 2 of the OSI reference model. It ensures the trustworthy transmission of data across a physical link and is primarily concerned with physical addressing.

Network layer: Layer 3 of the OSI reference model. This is the layer in which routing is implemented, enabling connections and path selection between two end systems.

Transport layer: Layer 4 of the OSI reference model. It is responsible for reliable communication between end nodes over the network.

Session layer: Layer 5 of the OSI reference model. It is responsible for creating, managing, and terminating session between applications and overseeing data exchange between Presentation layer entities.

Presentation layer: Layer 6 of the OSI reference model. It defines how data is formatted, presented, and converted for use by software at the Application layer.

Application layer: Layer 7 of OSI reference model. It supplies services to application procedures such as electronic mail or file transfer.

Hub- Connects all computer LAN connections into one device or concentrator. Hubs can be considered multiport repeaters. Hubs operate in half duplex mode.

Bridge- A device for connecting two segments of a network and transmitting packets between them. Bridges operated in half duplex mode.

Switch- A device responsible for multiple functions such as filtering, flooding, and sending frames. Its works using the destination address of individual frames. Switches operate in full duplex mode.

Router- A Network Layer mechanism, either software or hardware, using one of more metrics to decide on the best path to use for transmission of network traffic.

Routing- The process of locating a path to the destination host.

Frame Relay- A more efficient replacement of the X.25 Protocol, Frame Relay is the industry standard, switched Data Link layer protocol that services multiple virtual circuits using HDLC encapsulation between connected mechanisms.

PVC-Permanent Virtual Circuit: In a Frame Relay network, a logical connection, defined in software, this is maintained permanently.

CIR-Commited Information Rate: A Frame Relay networks agreed upon normal rate of transferring information.

DLCI-Data Link Connection Identifier: Used to identify virtual circuits in a Frame Relay network.

Backbone-The basic portion of the network that provides the primary path for traffic sent to and initiated from other networks.

Bandwidth-The gap between the highest and lowest frequencies employed by network signals. It refers to the rated throughput capacity of a network protocol or medium.

Congestion-Traffic that exceeds the networks ability to handle it.

Encryption-The conversion of information into a scrambled form that effectively disguises it to prevent unauthorized access.

Enterprise Network-A privately owned and operated network that joins most major locations in a large company or organization.

Ethernet-A base band LAN specification created by Xerox Corporation and then improved through the efforts of other companies.

Fast Ethernet-Any Ethernet specification with a speed of 100MBPS.

10BaseT-Ethernet 10MBPS over copper.

100BaseT-Ethernet 100MBS over copper.

1000BaseT-Ethernet 1000MBPS over copper.

1000BaseFX-Ethernet 1000MBPS over fiber.

Frame-a logical unit of information sent by the Data Link layer over a transmission medium.

Half Duplex-The capacity to transfer data in only one direction at a time between a sending unit and receiving unit.
Full Duplex-The capacity to transmit information between a sending station and a receiving unit at the same time.

IP-Internet Protocol.

IP Address-Often called an Internet address, this is an address uniquely identifying any device (host) on the Internet (or any TCP/IP network). Each address consists of four octets (32 bits), represented as decimal numbers separated by dotted decimals. Example of an IP address

Protocol-The specification of a set of rules for a particular type of communication.

-the basic logical unit of information transferred. It consists of a certain number of data bytes, wrapped or encapsulated in headers and/or trailers that contain information about where the packet came from and where it’s going.

TCP/IP-Transmission Control Protocol/Internet Protocol. The suite of protocols underlying the Internet.

Virtual Circuit-(a.k.a. VC)-a logical circuit devised to assure reliable communication between two devices on a network