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 172.16.40.6.
Protocol-The specification of a set of rules
for a particular type of communication.
Packet-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
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