DCN286 INTRODUCTION TO DATA
COMMUNICATION TECHNOLOGY
Network Fundamentals
Network hardware/software
Network hardware:
NIC on the computer
Hub/switch/router
Cables (or wireless router/NIC)
Patch panel and cable jacks
Network Software:
Protocols
Application software programs
Network Standard Organizations
Abbreviation
ISO
IETF
IEEE
ANSI
TIA
EIA
ITU
Full Name
International Organization for
Standardization
Internet Engineering Task Force
Institute of Electrical and Electronic
Engineers
American National Standards Institute
Telecommunications Industry
Association
Electronic Industries Alliance
International Telecommunications
Union
Cisco IBM Products Symbols
Cisco LAN Symbols
More Cisco Icons
Cisco People Icons
Cisco WAN Icons
Cisco Building Icons
Network Topologies
Bus
Star
Ring
Mesh
Network Topology
Ethernet
Ethernet is a family of frame-based
computer networking technologies for local
area networks (LANs). The name comes
from the physical concept of the ether.
Old Ethernet 10Base2 and 10Base5
Use Coaxial cable (TV cable)
10 means 10mbps
BASE means baseband
2 or 5 means 200m / 500m length limit
Bus topology
10BASET
The 10Base-T standard (also called
Twisted Pair Ethernet) uses a twisted-pair
cable with maximum lengths of 100
meters. The cable is thinner and more
flexible than the coaxial cable used for the
10Base-2 or 10Base-5 standards.
Its bandwidth is as same as 10base2 or 10
base5. But, it is using different connector,
RJ45. It also use STAR topology.
100BASE-TX
10BASE-T and 100BASE-TX
only require two pairs to
operate, pins 1 and 2
(transmit or TX), and pins 3
and 6 (receive or RX).
The cabling length limit is 100
meter.
1000BASET (gigabit)
All connection cables must be qualified to
1000mbps.
All switches, equipment NICs and
connectors must be qualified to
1000mbps.
Ethernet
Cabling
Repeater
10base5 – 500meter cable length limit;
10base2 - 200meter cable length limit;
10BaseT - 100meter cable length limit;
Repeater is to amplify signal and extend the
cabling distance.
Working in layer 1 (Physical) of TCP/IP
model
Hub
Central connection of Ethernet LAN.
Physically Star topology and could be
logically RING, Bus and/or Star
May have built-in repeater
Working in layer 1 (Physical) of TCP/IP
model
Ethernet Bridge
 Intelligent device to forward frame according to
destination Media Access Control (MAC)
address
 Forwarding: If the destination MAC address has
a port different to the originate port, the frame
will be sent.
 Filtering: If the destination MAC address is
reachable with the same interface when it
arrived, the frame will be discarded.
 Working in layer 2 (Data Link) of TCP/IP model
Switch
Think switch as a hub with bridge functioning on
each port (interface):
1. Switch will offer central connection to all hosts.
2. Switch will only forward frame according to
destination MAC address on per-port base.
3. Will regenerate signals (repeater function)
4. Most switches are working in layer 2 (Data
Link) of TCP/IP model.
Router
Redirect packets according to destination
logical address (IP address).
Can build routing path between different
network segments (subnets)
Can act as firewall
Can work as VPN (server) connection
Working in layer 3 (Network) of TCP/IP
model
LAN (Local Area Network)
Has physical high speed connections in
the network.
Usually in the same office building.
Private owned network.
May contain one to hundreds computers
Local-area Networks (LANs)
WAN (Wide Area Network)
 Connected by more than one LANs.
 Connection could be dedicated line, lease line
and / or other remote connections:
Modem (dial up) 56Kbps over analog phone line.
ISDN (Integrated Services Digital Network) 128Kbps
DSL (Digital Subscriber Line): over digital phone line
such as Bell Sympatico
Frame Relay
T1, T3, E1 or E3 lease line
 SONET (Synchronous Optical Network): using Optical
Carrier (OC)
Wide-area Networks (WANs)
VPN (Virtual Private Network)
VPN is a kind of encryption tunnel built
based on internet connection. It could be:
Site-to-Site (two locations of same or
different organizations connection)
Point-to-Site (for travelers)
VPN must have three components working
together: VPN server, VPN client and VPN
protocol such as L2TP and PPTP.
MAN and SAN
MAN (Metropolitan-Area-Network) is
between LAN and WAN.
SAN (Store-Area-Network) is for
performance (load balance), availability
and scalability. The server farm is a typical
example of SAN.
Bandwidth
Term
Bits per second (bps)
Number of Bits Per
Second
1
Kilobits per second (kbps)
1 thousand
Megabits per second (Mbps) 1 million
Gigabits per second (Gbps)
1 billion
Terabits per second (Tbps)
1 trillion
LAN bandwidth
10 Mbps: 10BASE2 (185m), 10BASE5
(500m) and 10BASE-T (100m)
100Mbps: 100BASE-TX (100m Cat 5
cable), 100 BASE-FX (2000m optic fiber),
1000Mbps: 1000BASE-TX (100m Cat5e
cable), 1000BASE-SX (220m/550m optical
fiber), 1000BASE-LX (500m single mode
optical fiber)
WAN bandwidth
WAN connection
Bandwidth
Dial up
56Kbps
ISDN
128Kbps
DSL
128Kbps – 6.1Mbps
T1
1.5Mbps
T3
44.736 Mbps (28T1)
STS1 (OC-1)
51.84Mbps
STS3 (OC-3)
155.52Mbps
STS48 (OC-48)
2.5Gbps
STS192 (OC-192)
10Gbps
Bandwidth planning
Predict business demand
Bandwidth is not free
Reserve the upgrade option
TCP/IP ISO OSI model
Name
7 Application
6 Presentation
5 Session
Description
Interact with programs. Application protocols
are HTTP, HTTPS, FTP, IMAP, SMTP, POP3,
and Telnet
Format conversion, encryption and decryption
3 Network
Establish, maintain and terminate connection
sessions between hosts
Error recovery and segment. UDP and TCP
are here.
IP addressing and routing
2 Data Link
MAC addressing and switching
1 Physical
Defines the electrical and physical
connections
4 Transport
TCP/IP model
Name
Description
Application
Covers 3 layers of OSI
model: Application,
Presentation and Session )
Transport
Transport
Internet work
Equals to Network
Network Access
Equivalent to Data Link and
Physical Layer of OSI
Encapsulation
1. Application layer add application protocol
header.
2. Transport layer add TCP or UDP header and
breaks into Segment which has TCP header and
data.
3. Network layer adds logical address header and
the PDU packets have IP header and data
4. Data link layer adds header including
destination MAC address. Frame has Ethernet
header, trailer and data.
5. Physical layer will be responsible to transmit bits
(electrical signals) over the medium.
De-encapsulation
1. According to the Ethernet encoding
scheme, assemble received bits.
2. Frames would be delivered according to
destination MAC address.
3. Or, the packet is routed to destination IP
address.
4. Transport layer protocol (TCP) may
assemble segment
5. Application layer will interpret the data
from segments.
PDU
Bit
Frame
L1PDU for electrical
signals
L2PDU
Packet
L3PDU
Segment
L4PDU
Bit
L7PDU for data
Question
Any question?
If you do not have question, please practice
conversion calculation between binary and
decimal numbering system.
1. Please convert decimal value 123, 240 and
255 to binary.
2. Please convert binary value 11001101,
10010011 and 00110011 into decimal value.