Transcript Technical Report

Bandwidth in the Local and Wide
Area Network
ATM
56k
Megabit
SONET
T1/T3
OC 192
X.25
Gigabit
Monmouth County Vocational Schools /
Advanced Networking Program
William Portilla
What is Bandwidth ?
The amount of data that can be transmitted
in a fixed amount of time.
For digital devices, the bandwidth is usually
expressed in bits per second(bps) or bytes
per second(Bps). For analog devices, the
bandwidth is expressed in cycles per
second, or Hertz (Hz)
Terms Used to Measure
Bandwidth
- Shown in decimal
deka (da) = 10 ^ 1 = 10
ten
hekto (h) = 10 ^ 2 = 100
hundred
kilo (k) = 10 ^ 3 = 1,000
thousand
mega (M) = 10 ^ 6 = 1,000,000
million
giga (G) = 10 ^ 9 = 1,000,000,000
billion
tera (T) = 10 ^ 12 = 1,000,000,000,000
trillion
peta (P) = 10 ^ 15 = 1,000,000,000,000,000
quadrillion
exa (E) = 10 ^ 18 = 1,000,000,000,000,000,000
quintillion
zetta (Z) = 10 ^ 21 =1,000,000,000,000,000,000,000
sextillion
yotta (Y) = 10 ^ 24 = 1,000,000,000,000,000,000,000,000
Data Transmission Bandwidth Measurement
The bandwidth or data-carrying capacity of a channel
such as a network cable, a modem, or a phone line is
commonly measured in bits per
second.
kilobit (kb) = 1,000 bits
Kilobit (Kb) = 1,024 bits
bps = bits per second
kbps = kilobits (1000 bits) per second (decimal)
Kbps = Kilobits (1024 bits) per second (binary)
kBps = kilobytes (1000 bytes) per second
KBps = Kilobytes (1024 bytes) per second
Mbps = megabits (1,000,000 bits) per second (decimal)
Mbps = megabits (1,048,576 bits) per second (binary)
MBps = megabytes (1,000,000 bytes) per second (decimal)
MBps = megabytes (1,048,576 bytes) per second (binary)
LAN Bandwidth
Local Area Networks supply bandwidth based upon
their physical and data link layer properties:
Token Ring - 4/16/100 Mbps
10Base T - 10 Mbps
100Base T - 100 Mbps (fast Ethernet)
FDDI – 100 Mbps (campus backbone)
Gigabit Ethernet - 1,000 Gbps
ATM - 150kbs to 600kbs (high QOS)
WAN
Bandwidth
Wan connections are comprised of several types of
technologies each with its' own unique interface and transfer
rate. A WAN uses the Physical and Data link layers to define
Bandwidth.
• ASYNCHRONOUS CONNECTIONS - 56k modem
• SYNCHRONOUS CONNECTIONS - DSU/CSU - T1/T3
lines - T1= 1.54mbps / T3 = 44.7 mbps (28 T1’s)
• ISDN - (2) 64kbps channels - aggregate 128kbs - and higher
by combining ISDN lines (video conferencing)
• X.25 -The ITT standard for connecting terminal equipment
to packet switching data circuits. Max effective speed 2mbps
• FRAME RELAY - can offers users transmission speeds of
2.048 megabits per second and higher. It allows faster speeds
than the X.25 packet switching standard.
WAN Bandwidth(cont.)
– SONET - Synchronous Optical Network, a standard for connecting
fiber-optic transmission systems with speeds ranging from 51.8 Mbps
(about the same as a T-3 line) to 2.48 Gbps. for Optical Carrier, used
to specify the speed of fiber optic networks conforming to the SONET
standard. The table shows the speeds for common OC levels.
– OC = Speed
OC-1 = 51.85 Mbps
OC-3 = 155.52 Mbps
OC-12 = 622.08 Mbps
OC-24 = 1.244 Gbps
OC-48 = 2.488 Gbps
OC-192=9.952 Gbps
ATM- Asynchronous Transfer Mode. A method of communications in
which information is transmitted in "cells". Transmission rates from
150 megabits per second to 600 mbps.
When Data Pipes of Unequal Bandwidths
Encounter One Another
Network traffic gets in trouble primarily when a high-speed
segment meets a low-speed segment. IP was designed to run
over links with low throughput rates-low by today's standards,
that is. The variation between the slowest links and the fastest
ones was once 110 bits/sec and 2,400 bits/sec-a ratio of slightly
more than 20 to 1. Compare that ratio with one you might
observe on a typical router configuration today: A router with a
56Kbit/sec frame relay interface and a 100Mbit/sec LAN
interface has a ratio of approximately 2,000 to 1. The same
router with a 1Gbit/sec LAN interface has a ratio of 20,000 to 1.
If a thin pipe fills up and a fat pipe full of traffic is destined for
the slow interface, the only thing the router can do is start
throwing packets away or putting them into a buffer or queue. If
the throughput mismatch is large, the buffers had better be
large.
Multiplexing to Increase
Bandwidth
A multiplexer optimizes the use of
communications facilities by configuring
and bringing together many channels for
efficient transmission on a network.
Fiber Optic Multiplexer manufacturers can
increase the capacity of a single fiber 400
fold by multiplexing multiple wavelengths
over a single fiber.