INTRODUCTION TO DATA
NIC on the computer
Cables (or wireless router/NIC)
Patch panel and cable jacks
Application software programs
Network Standard Organizations
International Organization for
Internet Engineering Task Force
Institute of Electrical and Electronic
American National Standards Institute
Electronic Industries Alliance
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Ethernet is a family of frame
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
T standard (also called
Twisted Pair Ethernet) uses a twisted
cable with maximum lengths of 100
meters. The cable is thinner and more
flexible than the coaxial cable used for the
2 or 10Base
Its bandwidth is as same as 10base2 or 10
base5. But, it is using different connector,
RJ45. It also use STAR topology.
T and 100BASE
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
All connection cables must be qualified to
All switches, equipment NICs and
connectors must be qualified to
500meter cable length limit;
200meter cable length limit;
100meter cable length limit;
Repeater is to amplify signal and extend the
Working in layer 1 (Physical) of TCP/IP
Central connection of Ethernet LAN.
Physically Star topology and could be
logically RING, Bus and/or Star
May have built
Working in layer 1 (Physical) of TCP/IP
Intelligent device to forward frame according to
destination Media Access Control (MAC)
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
Think switch as a hub with bridge functioning on
each port (interface):
Switch will offer central connection to all hosts.
Switch will only forward frame according to
destination MAC address on per
Will regenerate signals (repeater function)
Most switches are working in layer 2 (Data
Link) of TCP/IP model.
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
LAN (Local Area Network)
Has physical high speed connections in
Usually in the same office building.
Private owned network.
May contain one to hundreds computers
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:
odem (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
T1, T3, E1 or E3 lease line
SONET (Synchronous Optical Network): using Optical
area Networks (WANs)
VPN (Virtual Private Network)
VPN is a kind of encryption tunnel built
based on internet connection. It could be:
Site (two locations of same or
different organizations connection)
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
between LAN and WAN.
Network) is for
performance (load balance), availability
and scalability. The server farm is a typical
example of SAN.
Number of Bits Per
Bits per second (bps)
Kilobits per second (kbps)
Megabits per second (Mbps)
Gigabits per second (Gbps)
Terabits per second (Tbps)
10 Mbps: 10BASE2 (185m), 10BASE5
(500m) and 10BASE
TX (100m Cat 5
cable), 100 BASE
FX (2000m optic fiber),
TX (100m Cat5e
SX (220m/550m optical
LX (500m single mode
44.736 Mbps (28T1)
Predict business demand
Bandwidth is not free
Reserve the upgrade option
TCP/IP ISO OSI model
Interact with programs. Application protocols
are HTTP, HTTPS, FTP, IMAP, SMTP, POP3,
Format conversion, encryption and decryption
Establish, maintain and terminate connection
sessions between hosts
Error recovery and segment. UDP and TCP
IP addressing and routing
2 Data Link
MAC addressing and switching
Defines the electrical and physical
Covers 3 layers of OSI
Presentation and Session )
Equals to Network
Equivalent to Data Link and
Physical Layer of OSI
1. Application layer add application protocol
2. Transport layer add TCP or UDP header and
breaks into Segment which has TCP header and
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.
According to the Ethernet encoding
scheme, assemble received bits.
Frames would be delivered according to
destination MAC address.
Or, the packet is routed to destination IP
Transport layer protocol (TCP) may
Application layer will interpret the data
L1PDU for electrical
L7PDU for data
If you do not have question, please practice
conversion calculation between binary and
decimal numbering system.
Please convert decimal value 123, 240 and
255 to binary.
Please convert binary value 11001101,
10010011 and 00110011 into decimal value.