DCN286 INTRODUCTION TO DATA
COMMUNICATION TECHNOLOGY
LAN and WAN cabling and
devices introduction
Digital signal transmission
 Electrical signals can be transmitted over coaxial
cable, STP, UTP cables
 Light signals can be transferred over fiber optic
cable which has advantages over copper:
• SPEED: Fiber optic networks operate at high speeds up into the gigabits
• BANDWIDTH: large carrying capacity
• DISTANCE: Signals can be transmitted further without
needing to be "refreshed" or strengthened.
• RESISTANCE: Greater resistance to electromagnetic
noise such as radios, motors or other nearby cables.
• MAINTENANCE: Fiber optic cables costs much less to
maintain.
Review of Ethernet cables
Ethernet
Types
Media
Max segment length
Connector
10BASE2
50ohm coax (Thinnet)
185m
BNC
10BASE5
50ohm coax (Thicknet)
500m
AUI
10BASE-T
TIA/EIA Cat3, 4, 5 UTP
100m
RJ45
100BASE-TX
TIA/EIA Cat5 UTP, 2 pairs
100m
RJ45
100BASE-FX
62.5/125 multimode fiber
400m
Duplex media interface
connector (MIC), ST or
SC
1000BASE-CX
STP
25m
RJ45
1000BASE-T
TIA/EIA Cat5 UTP, 4 pairs
100m
RJ45
1000BASE-SX
62.5/125 multimode fiber
275m for 62.5 micro fiber; SC
550m for 50 micro fiber
1000BASE-LX
62.5/125 multimode fiber;
9micron single mode fiber
440m for 62.5 micro fiber; SC
550m for 50 micro fiber;
3-6km for singlemode
fiber
Connectors (optional)
LAN review
Local Area Networks (LAN) is a collective group of
computers, or computer systems, connected to
each other allowing for shared program
software or data bases. LAB should have high
speed and reliable connections.
LAN can fall in 3 categories:
1. End-user level: linking user equipments (PC,
laptop, PVR) to a hub/switch/router.
2. Workgroup level: linking between hubs/switches
which are used to connect user equipments.
3.Backbone level: Links between the hubs/switches
in LAN core
Switches and Links
 Access switches and links
Access switches are used in LAN connecting user
devices. The links of access switches are Access
Links.
 Distribution switches and uplinks
Those access switches are connecting to upper
level switches, distribution switches. Links between
access switches and distribution switches are
uplinks.
 Core switches and links
The distribution switches are connected to central
switches, core switches. Links between distribution
switches and core switches are core links.
Switches used in Data Centre (optional)
Switches used in Campus LAN (optional)
Switches used in branch (optional)
Switches used in Service Provider (optional)
UTP cable pin outs
The TIA/EIA T568-A
and TIA/EIA T568-B
are the standard to
prepare the Ethernet
cables. It is a kind of
essential skills for a
network tech.
For straight through
cable, sequence is
same on both ends.
100Mbps crossover cable
For 100BASE-T, only
two pairs cross each
other on both sides.
Look that the pin 1
and 2 of side A are
placed as pin 3 and
6 on another end,
side B. Pin 3 and 6
of side A are placed
on pin 1 and 2 on
another end, side B.
1000Mbps crossover cable
For 1000BASE-T, all
four pairs are cross
each other on both
sides.
Transmit pins
Pin 1 and 2: PCs, routers, servers,
wireless access points Ethernet
connection
Pin 3 and 6: Switches, hubs, bridges,
repeaters
Connection of straight through cables
Switch to router
Switch to PC or server
Hub to PC or server
Crossover cable
Switch to switch
Switch to hub
Hub to hub
Router to router
PC to PC
Router to PC
Auto-mdix (Automatic Mediumindependent Crossover)
 If the Auto-mdix is enabled by default,
straight-through cable can also be used
between two switches
 But, it is possible the feature is disabled by
default. Please verify manufacturers’
documents.
Standard Tests for Cable Certification
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Wiremap: Identify physical error of any mis-wiring
Insertion loss: Lose of signal strength, expressed in dB.
NEXT: A higher value is desirable, meaning better cable performance
PSNEXT: Combined NEXT
Equal-level Far-end Crosstalk (ELFEXT): FEXT is usually less detrimental
to a signal than NEXT
Power sum equal-level far-end crosstalk (PSELFEXT): sum of all FEXT
Return loss: measured in dB and indication of bad crimp or bad connection
at the RJ45 plug.
Propagation delay: tests for the time it takes for the signal to be sent from
one end and received by the other end
Cable length: Verify not exceed 100m. Also find shortcut or where the
broken point is
Delay skew: Tests for difference between the fastest and slowest set of
wire pairs. Lower is better. Could be between 25-50 nanoseconds over
100m
Repeater
 The digital signals are
transferred by electrical, light,
microwave and other wireless
energies. Those energies
would be degraded and that
is the reason why the max
length of single segment
length of various cables could
be defined. To remain the
signal strength, repeater can
amplify degraded signals
back to clear signal level.
5-4-3 rules for repeater
Repeaters cannot be used to extend
network without limit.
5-4-3 rules in 10BASE-T: Max. 5 cables
and 4 repeaters can be used between any
2 end user devices. Only 3 can have end
user devices connected.
Hubs
 Central connection device
 Repeat the incoming signals
before transmitting them on to
their destinations
 Passive, active and intelligent
are three Ethernet hub types.
***Hub is working in physical
layer of TCP/IP ISO/OSI
model.
Network Bridges
Can connect multiple network segments
and regenerate clear signals
Can analyze incoming data packets by the
destination MAC address before
rebroadcast them to other segments:
forwarding (if the destination is reachable
on the other side) and filtering (if the
destination is on the same side)
Work in layer 2 of ISO/OSI TCP/IP model
Ethernet switch
Can connect multiple segments with
regenerating clear signals
Can handle multiple frame
forwarding/filtering simultaneously.
May offer VLAN (Virtual LAN) features
Can support full-deplex mode
Switch works in layer 2.
Wireless tech introduction
 Infrared
 Bluetooth
 Microwave
 Radio
 Wi-Fi
In general, wireless network is secondary because
of two concerns: speed and security. But, it does
offer mobility and convenience.
Main wireless components
 Access point: linking wireless network to the
wired world.
 Wireless NIC is required on each hosts in the
network with authentication configuration.
 Wireless hub, switch and router: functioning as
same as regular wire connected equipments
WLAN standards organizations
IEEE published the WLAN standard.
FCC (Federal Communication
Commission) will specify restriction on
power and radio frequencies in US.
Industry Canada is taking care of radio
frequency usage in Canada.
Frequency use/approval may be different
in various areas, regions and countries.
NIC (Network Interface Card)
The most common language or
protocol for LANs is Ethernet,
sometimes referred to as IEEE
802.3. (FDDI and Token Ring
are other LAN protocols)
LAN model
 Peer to peer (Also referred as workgroup model)
No central authentication. Host could be server
and client in different times
 Client/Server (Some people called this as
domain model)
Central authentication is handled by domain
controller. Resources are shared on server side
and client PCs are connecting via network.
WAN (Wide Area Network)
WAN could be thought that many LANs are
connected by:
 Dedicated connection (physically private owned)
 Leased Line between LANs (Logically private
owned)
 Remote connection over public network
connection (Internet connection): VPN (Virtual
Private Network), RAdmin, PCAnywhere,
GoToMeeting, LogMeIn, VNC or other remote
access software
VPN (Virtual Private Network) (optional)
Main components:
 VPN server (could be a dedicated box, hardware
VPN server or a software program running on a
server)
 VPN client (could be a dedicated box, hardware
VPN client usually linking sites or a software
program running on a client computer to connect
to VPN server)
 VPN protocols: L2TP (Layer 2 Tunnel Protocol)
or PPTP (Point to Point Tunnel Protocol)
Internet connection
 Dialup (adding modem to analog telephone line
with connector RJ11)
 T1 (1.5Mbps), T3 (45Mbps) are using CSU/DSU
network with RJ48 connector)
 DSL (ADSL, SDSL, VDSL, HDSL, etc, etc):
Digital Subscriber Line is to transfer voice and
data over digital phone line
 Frame Relay
 Cable internet connection (Coax cable)
 IDSN (RJ11 and RJ45 connections)
 Cell phone and other Mobile Hi-Speed Internet
 Satellite connection
T1/T3 connector (Optional)
Bantam
connectors
might be
used by
T1/T3.
ISDN “modem” (optional)
The correct name should be
ISDN terminal adapter
You can find external or
internal adapter in which
RJ11 connections are used
to connect digital phone line
and RJ45 is used to connect
to LAN.
Satellite Antenna (optional)
Serial port connection
Most WAN links are serial connection. Such
connections require CSU/DSU (Channel
Service Unit/data Service Unit). You can
understand it as a “modem” or “adapter”
between your LAN and WAN link. It is
possible to have a connection adapter to
convert the serial port connection to RJ45
style.
DTE/DCE
 DTE (Data Terminal Equipment)
DTE is usually end user device and it receives
clocking.
 DCE (Data Communication Equipment)
DCE is usually on upstream side and it defines
clocking (transfer speed) for DTE.
The male and female connections as the picture
Serial port connectors
Connection Side A
EIA/TIA-232 25 pins
Side B
9 pins
EIA/TIA-449 37 pins
9 pins
V.35
30 pins
9 pins
X.21
15 pins
9 pins
EIA/TIA-530 25 pins
9 pins
Cisco DTE/DCE connectors (optional)
 Cisco EIA/TIA-232
(RS-232) DCE cable
has female
connector (holes) on
the D60 connector
side
 Cisco EIA/TIA-232
(RS-232) DTE cable
has male connector
(pins) on the D60
connector side
Fixed or modular routers
If the router has only permanent
interfaces, it is a fixed router and you
cannot add any extension cards inside.
Cisco routers could be modular style in
which, additional interface (modular) cards
are allowed to be inserted
Cisco fixed router
Cisco modular router
 The two plates cover the
potential extension cards
inserting in upper section of
the Cisco 3640 router
Extension module card (optional)
 Cisco High-Speed WAN Interface
Card expansion module
 Cisco High-Speed WAN Interface
Card serial adapter
 Cisco WAN Interface Card (WIC) - 4
x 10/100Base-TX WAN - WAN
Interface Card (WIC)
 Cisco 1-port ADSLoPOTS WAN
Interface Card - 1 x ADSLoPOTS
WAN - WAN Interface Card (WIC)
Cisco router console cable
 Beside connecting RJ45 to fast Ethernet
ports, DTE or DCE cables to serial ports,
console cable (roll-over) is used to connect
Cisco router console port to computer serial
port
 In Hyper Terminal, have following setup
9600bps
8 data bits
No parity
1 stop bit
No follow control
Remote control the router (Optional)
In general, router could be managed by:
Console (directly connected)
Aux port with modem connection
Network control via Ethernet or serial port
Question
Any question?
If you do not have question, please
search internet and collect more
information of those LAN, WAN, switch
and router. Such as brand and makers’
name
1. Please be aware regular models of
Cisco router and switches.
2. Please be familiar with those hardware
and concepts.