Telecom Networks

Da Communic an
ta ation
d
EmaNetwor
sonvq@hcmut
il: .edu.vn
king

Telecomm.
Dept.

DCN2013

1


Cont
 Chapter 5:
ent
Telecom Networks
802.x standard
IP Addressing: an VLS
Ethernet, Token Pass, Token
Classless
d M
Ring
Switc
an Routi
Network devices

hing

Telecomm.
Dept.

d ng

DCN2013

2


Local
Area
A local area network (LAN) is a
computer
network
that
Network
school,
laborat o offi buildi usi netw


interconnects
computers
in a limited
computer
ory,
r
ce
ng

ng ork

area
mediasuch as a home,
Medium:
 Coaxial cable
 Twisted-pair line

Telecomm.
Dept.

DCN2013

3


Wide
Area
A wide area network (WAN) is a
network
that
covers
a
broad
Network
metropolitan, regional, bounda usi priv


o
netw

transp
area
(i.e.,
any
telecommunications
orpub
national
ries)
ng ate
rnetwork
lic orkthatorts
links across

Telecomm.
Dept.

DCN2013

4


Topology
Bus

Ring

Star

Telecomm.
Dept.

Physical
Extended Star

Hierarchical

Mesh

DCN2013

5





Project
IEEE 802 refers to a family of IEEE
standards dealing
with local
802
area networks and metropolitan area

networks
Control
(LLC)and
andprotocols
Cont (MA
s th th
The services

specified
in
thi
layers
can
be
Media
Access
IEEE 802
map to the rol C), o at e
listed
lower like
two layerss:(Data Link and Physical)
Data link layer
of the seven-layer
•
LLC
Phys
lay reference model. In fact,
OSI networking
Sublayer:
ical
IEEE
802 er
splits the
Telecomm.
DCN6
Dept.• MAC
2013






Modules in Project
802
LLC: based on HDLC
protocol
 Multiplexing
protocols
transmitted over
the MAC
layer (when
transmitting) and
decoding them
Telecomm.
(when
Dept.

Project 802

DCN2013

7


 LLC PDU:

formats

LLC Frame

DSAP: Destination

Service
SSAP: Servi
Access
Point
Source
ce
 Access
fiel
Contr
Pointd:

ol

format

HDLC
Telecomm.
Dept.

DCN2013

8

Ether
 Topology: bus, star, ring
 Media Access
Control:
net

Deterministic, Non-deterministic
 Addressing:
Every computer has a unique way of identifying itself :
MAC address or physical address.
The physical address is located on the Network Interface

Card (NIC).
MAC addresses have no structure, and are considered flat
address spaces. MAC addresses are sometimes referred to
as
burned-in addresses (BIAs) because they are burned
Telecomm.
DCN9
Dept.

2013


IEEE
802.3:
frame
Preamble: 10101010 (7 bytes)
The Start Frame field (10101011) tells other
format

devices on the network that a







frame is coming down the wire.
The Address field stores the source and
destination MAC addresses.

 Source address is unicast, Destination address can be
unicast, multicast or broadcast

The Type/Length field is an optional field

 Exact length of frame, or Layer 3 protocol making the
sending request, or Not used

The Data field is the actual information being
Telecomm.
DCNsent
by
the
upper
layer
Dept.
2013

1


Ethernet:
10Base- 50Ω Thin cable,
2:
185m.
802.3










10Base-5:
10Base-T:
10Base-F:
100Base-TX:
100Base-T4:
100Base-FX:
1000Base-T:

Telecomm.
Dept.

50Ω Thick cable, 500m.

100Ω UTP cable, 100m.
Fiber optic cable, 1000m.
100Ω UTP/STP cable, 100m.
100Ω UTP (4p) cable, 100m.
m.
Fiber optic cable, 400m.
100Ω UTP/STP cable, 100

DCN2013

1


Ethernet:
NIC: Network
MAU:
Medium
Un
Interface
Card
10BASE-5
Attachment
it





50
cabl(thicknet)

500
ThickThi
Ethernet
Ω ck e, m

Telecomm.
Dept.

DCN2013

1


Ethernet:
Thin
50
Thin 185
Ethernet
10BASE-2
Ω cable, m.



Telecomm.
Dept.

DCN2013

1

Ethernet:
Twisted-pair
cable
10BASE-T
Da rat 1 Mb




100Ω UTP cable, 100m.

ta e: 0 ps

Telecomm.
Dept.

DCN2013

1


Ethernet
Specified by the technology
being used.
Operation
Determine who can transmit
and when.
Two types:
Deterministic: “Let’s take

turns”.
• Token-Ring, FDDI.

Non-deterministic: “First
come,
Carrier Sense Multiple
first serve”.

Access
with
Collision
Telecomm.
• Ethernet : CSMA/CD.
Dept.
Detection
(CSMA/CD).

DCN2013

1


Three common layer 2
Ethernet:
technologies
logical
broadcast
Token Ring:
topology
logical

token
ring
FDDI: token
topologyring
logical
Telecomm.
Dept.

topolog

DCN2013

1


Ethernet

Ethernet is a shared-media
MAC
broadcast
technology. The access
method CSMA/CD
used in Ethernet performs
Detec erro with da pack o o th
three functions:
ting
rs
in
ta

ets
r
n
e
Transmitting and receiving data packets
netw data packets and checking them for
Decoding
Telecomm.
Dept.

DCN2013

1


Process

Telecomm.
Dept.

CSMA/CD

DCN2013

1



Speed:
100

Mbps

 Distance: <250m

Ethernet

Fast

Ether
Backward
net

Us
Twisted
o
Fib
compatible with
es
-pair
r
er
10 Mbps

Telecomm.
Dept.

DCN2013

1


>1 Gbps

Using Fiber optic

Deployed as backbone

Ethernet

Gigabit

network,
Fa
Ether
netwo
connecting st
net rks

Telecomm.
Dept.

DCN2013

2




Token Ring

Token ring LAN
technology was a
protocol which resided at
the data link
layer (DLL) of the OSI
model. It used a
 special three-byte frame
Initially used only in IBM i
was
eventually
wit
called
a
token
computers,
t
hthe
 standardized
that
travels
around
Physical topol
protocol
IEEE
Telecomm.
ring.
Tokenring
ogy
Dept.

DCN2013

2






Token
The data transmission process
goes as follows:
Ring

 Empty information frames are continuously circulated
on the ring.
 When a computer has a message to send, it seizes the
token. The computer will then be able to send the
 frame.
The frame is then examined by each successive
workstation. The workstation that identifies itself to
 be the destination for the message copies it from the
frame and changes the token back to 0.
When the frame gets back to the originator, it sees
that the token has been changed to 0 and that the

message has been copied and received. It removes
the message from the frame.
The frame continues to circulate as an "empty"

Issues:

ready to be
taken by a
frame,
Who generates
token?
workstation
when
it
has
Telecomm.
If the node keeping token is
a
message
to
send.
Dept.
dead, what happens?

DCN2013

2


Token
Bus
Also use token as Token Ring



Physical Bus topology

Token bus was standardized by IEEE standard 802.4. It
is mainly used for industrial applications

Due to difficulties handling device failures and adding
stations to a network,
areputa fo bei
new

unrelia
an diffic
t upgra
token bus
gained
ble
d ult o de

Telecomm.
Dept.

tion

r ng

DCN2013

2

IP
Addressing:
An IPv4 address
is 32 bits
IPv4



long.

The IPv4
Addres
Sche
addresses
are
sing
mes.
unique and
universal.
Network
address + Host
Telecomm.
address:
Dept.

DCN2013

2

Classful
IP
In classful addressing, the is divided
address
space
into
five
addressing
In classful
alar pa o th availa addres



we
wastA, B, C, D,
classes:
addressing,
geand
rt E.
f e ble
re ed.

Telecomm.
Dept.

ses

DCN2013

2