Electrical Signal Transmission

1
Electrical Signal Transmission
Noise, attenuation and amplifiers. Sending
bits Acoustic couplers Modern Modems
2
Channel Limits
Nyquist D 2 B log2(K) D bits /
second B Bandwidth (Hz) K number of
encoded levels (log2(K) bits of
encoding) Shannon C B log2( 1 S/N) C
channel capacity (bits / second) S/N signal /
noise ratio
3
Connecting Computers Signals
4
Connecting Computers Signals
Phase Shift Modulation
5
Connecting Computers
Comer The Internet Chapters 4, 5, 6
6
Computer to Computer
RS 232 (DB25 connector) Computer transmits on
pin 2, receives on pin 3 (Modem transmits on pin
3, receives on pin 2) Ground pin 7
7
ISO OSI Stack
8
Networking Computers
9
Multiplexing
10
ISO OSI Stack
11
Protocol Stacks
12
Local Area Networks
Point-to-Point Connections
13
Facts About LANs

• LANs are incompatible.
• Many LANs and fewer WANs
• The desirability of a single network.

14
LAN Taxonomy Tree

• Access Control
• Transmission Media
• Topology
• Transmission Technique
• Typical data rates

15
Point-to-Point Network
Point-to-Point Connections over a Network
16
Star Topology
17
Ring Topology
18
Bus Topology
19
Ethernet
Ethernet began at Xerox PARC - 1970s DEC,
Intel, Xerox cooperated on standards IEEE now
controls Ethernet standard multiple
versions originally shared coaxial cable
(ether) 10Mb/s Fast Ethernet 100Mb/s
20
Ethernet Data Flow
21
LAN Connectivity

• Bridges
• Routers
• Gateways
• Servers