Transcript What is the Network

What is the Network ?
Two or more connected computers that can
Share resources such as :
• Data
• Printer
• Application
Network types ( LAN ,
MAN , WAN )
– Three main networking technologies are
used to connect computers and networks
together:
•
•
•
Local area network (LAN)
Metropolitan area network (MAN)
Wide area network (WAN)
LAN
Used to network computers located in a
limited geographical area such as a
room, floor, or building .
Speed : 1Mbps , 100Mbps , 1Gbps ,
10Gbps
MAN
A MAN is used to interconnect networks
that are larger than a LAN but smaller
than a WAN.
EXAMPLE OF A MAN
WAN
• Spans a large geographic area
• Defined as an internetwork that connects
many LANs using service provider.
• Examples of WANs
– The Internet
EXAMPLE OF A WAN
Topologies
Bus : physical
Star : physical
Ring : logical
Mesh : physical
UTP Implementation (StraightThrough)
Cable 10BASE-T/
100BASE-TX Straight-Through
Pin Label
1
2
3
4
5
6
7
8
TX+
TXRX+
NC
NC
RXNC
NC
1
2
3
4
5
6
7
8
Straight-Through Cable
Pin Label
TX+
TXRX+
NC
NC
RXNC
NC
Wires on cable ends
are in same order.
UTP Implementation
(Crossover)
Cable 10BASE-T or
100BASE-TX Straight-Through
Crossover Cable
EIA/TIA T568A
Pin Label
1
2
3
4
5
6
7
8
TX+
TXRX+
NC
NC
RXNC
NC
1
2
3
4
5
6
7
8
EIA/TIA T568B
Pin Label
TX+
TXRX+
NC
NC
RXNC
NC
Some wires on cable
ends are crossed.
Repeater
A repeater
• is a device that regenerates and
amplifies a signal, to counteract the
effects of attenuation
HUB
HUB
• is a device used to connect all of the
•
•
•
•
computers on a star network.
From the outside, a hub looks like nothing
more than a box with a series of cable
connectors and LEDs in it
Two Types: Active and Passive
Active :amplifies the signals and immediately
transmits them through all of the other ports.
Passive: transmits the signals through all of
the other ports .
Bridges
• Operate at Layer 2 of the OSI model
• Forward, filter, or flood frames
• Few ports
• Slow
Layer 2 devices
• A layer 2 device is a device that understand MAC,
for example:
 NIC (Network Interface Card)
 Bridge :
- address learning
- forwarding decisions are based on software
- bridge is used for LAN segmentation
- max. 16 port.
 Switch:
- a multi-port bridge up to 567 port
- forwarding decisions are based on hardware ASIC
(faster than bridge)
functions of a switch
- Address learning
- Forward/filter decision
- Loop avoidance ( Loop free )
Redundant Topology
– Redundant topology eliminates single points of failure.
– Redundant topology causes broadcast storms, multiple
frame copies, and MAC address table instability
problems.
Spanning Tree Protocol
Block
• Provides a loop-free (Loop Avoidance) redundant network
topology by placing certain ports in the blocking state
Router
functions of a router
- connect between networks
- Select best path
- Divide broadcast domain
- Packet forwarding
Identify Collision and Broadcast Domains
Collision domain =3 and Broadcast Domains=3
Identifying Collision and Broadcast Domains
Collision domain =8 and Broadcast Domains=5
Comparison
Connection-oriented
Connectionless
Sequencing
Fast delivery
Acknowledgement
Limited error checking
Reliable delivery
Unreliable delivery
Session establishment
Data recovery
TCP
UDP
Comparison
Clients
Servers
Any device that requests Any device that provides
services from a remote access to resources
application
(offer services(
Identifying Static and Dynamic
Routing
• Static Routing
– Uses a route that a
network
administrator
enters into the
router manually
•Dynamic Routing
–Uses a route that a
network routing
protocol adjusts
automatically for
topology or traffic
changes
Comparison
BRI
PRI
2B+D
23B+D
128Kbps
1.544Mbps
PSTN
T1 Lines
OSI 7 layer
• OSI Open System Interconnection
We want the system to be standard to can
any one use it
• ISO International Standard Organization
Make standarization to main task for
operation ( IEEE)
OSI Model Overview
Application
Application
(Upper)
Layers
Presentation
Session
Transport Layer
Network Layer
Data Link
Physical
30
Data Flow
Layers
Layer 7 - The Application Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
•It’s the S\w on our pcs that
is used to represent a user
interface to the network &
so aids the user to make
applications.
7- Application Layer
•
•
•
•
•
•
•
•
HTTP : Browsing protocol
FTP : File Transfer Protocol
TFTP : Trivial FTP
Telnet : Remote access protocol
SMTP : Simple Mail Transfer protocol
SNMP : Simple Network Management Protocol
DNS : Domain Name System
DHCP : Dynamic Host Configuration Protocol
Layer 6 - The Presentation Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
This layer is responsible
for presenting the data in
the proper format .
- Compression &
decompression of data
Examples:
AVI,JPG,….
Layer 5 - The Session Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
•Give orders for:
establishment, management,
and termination of the
session between different
application.
•Specifies communication
mode
( Half duplex – full duplex )
Layer 4 - The Transport Layer
•
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Responsible for actual
mechanism of:
1. Establishment of connection.
2. Management of connection:
2.1) segmentation.
2.2) sequencing.
2.4) error detection &correction.
2.5) flow control.
3. Termination of connection.
Examples:
• TCP (transmission control
protocol).
• UDP (User Datagram Protocol).
Flow control
Pc1
Pc2
Buffering
Congestion avoidence
stop
Go on
Layer 3 - The Network Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Responsible for:
1. End-to-end delivery.
2. Logical addressing .
EX:
IPv4,IPv6,IPX,APPLETALK
3. Routing (choose the best
path to destination.)
Layer 2 - The Data Link Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Responsible for:
1.Arbitration : find the best
time to send the data
( CSMA/CD & taken)
2.Hop-to hop data delivery.
3.Hop-to-hop addressing
(MAC Address in Ethernet).
4. error detection
4.1- parity check : but very week
4.2-CRC : Depend on mathematical
equation
Layer 2 - The Data Link Layer
•IEEE version
( IEEE 802.3 (MAC sub-layer)
“Interact with physical layer”
+
IEEE 802.2 (LLC sub-layer)
“Interact with Internet layer” )
Data-Link
Layer
Physical
Layer
IEEE 802.2
Logical Link
Control sub-layer
IEEE 802.3
Media Access
Control sub-layer
IEEE 802.3
Physical Layer
Ethernet II
Data link sub-layers :
LLC : (logical link control) places information in the frame that
identifies which Network layer protocol is being used for the
frame.
MAC : (media access control) provide physical addressing and
and delimiting of data according to the type of Data Link
layer protocol in use.
Layer 1 - The Physical Layer
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
It’s responsible for all
Physical properties of the
network :
1. Cable length.
2. Cable type.
3. Bit rate.
4. Voltage levels.
5. H/W interface types.
Encapsulating Data
Application
Presentation
Session
Upper Layer Data
TCP Header
Transport
Upper Layer Data
IP Header
Data
LLC Header
Data
FCS
MAC Header
Data
FCS
0101110101001000010
Protocol Data Unit (PDU)
Segment
Network
Packet
Data Link
Frame
Physical
Bits
De-encapsulating Data
Application
Presentation
Session
Upper Layer Data
Transport
Upper Layer Data
Network
TCP+ Upper Layer Data
IP + TCP + Upper Layer Data
Data Link
LLC Hdr + IP + TCP + Upper Layer Data
Physical
0101110101001000010
Protocols
•
•
•
•
•
•
•
•
•
•
•
•
Ethernet
IP
IPX
TCP
UDP
TFTP
FTP
TELNET
SNMP
DHCP
DNS
SMTP
•
•
•
•
•
PPP
Frame relay
ATM
HDLC
X.25
Commands
•
•
•
•
•
•
Ipconfig/all
Ipconfig/release
Ipconfig/renew
Ping
Tracert
nslookup
Port Numbers
Application
Layer
Transport
Layer
F
T
P
T
E
L
N
E
T
S
M
T
P
D
N
S
T
F
T
P
S
N
M
P
R
I
P
21
23
25
53
69
161
520
TCP
UDP
Port
Numbers
TCP Three Way
Handshake/Open Connection
Host A
1
Host B
Send SYN
(seq=100 ctl=SYN)
SYN received
SYN received
3
Established
(seq=101 ack=301 ctl=ack)
Send SYN, ACK 2
(seq=300 ack=101 ctl=syn,ack)
Address Resolution Protocol
I need the
Ethernet
address of
176.16.3.2.
I heard that broadcast.
The message is for me.
Here is my Ethernet
address.
172.16.3.1
172.16.3.2
IP: 172.16.3.2 = ???
IP: 172.16.3.2
Ethernet: 0800.0020.1111
• Map IP
• Local ARP
Ethernet
Reverse ARP
I heard that
broadcast.
Your IP
address is
172.16.3.25.
What is
my IP
address?
Ethernet: 0800.0020.1111 IP = ???
Ethernet: 0800.0020.1111
IP: 172.16.3.25
• Map Ethernet
IP
• IPv4 : 32 bit in decimal format
• IPv6 : 128 bit in hexadecimal
format
• DLCI:10 bit
• MAC address:48 bit
IP Address classes
Private IP Addresses
Subnetting
• What is the subnetwork address for a host
with the IP address 200.10.5.68/28?
•
•
•
•
A. 200.10.5.56
B. 200.10.5.32
C. 200.10.5.64
D. 200.10.5.0
Subnetting
• What is the broadcast address for a host
with the IP address 192.168.221.37
255.255.255.248?
•
•
•
•
A. 192.168.221.40
B. 192.168.221.33
C. 192.168.221.36
D. 192.168.221.39
VLAN Overview
• Segmentation
• Flexibility
• Security
VLAN = Broadcast Domain = Logical Network (Subnet)
VLAN Operation
• Each logical VLAN is like a separate physical bridge.
• VLANs can span across multiple switches.
• Trunks carry traffic for multiple VLANs.
• Trunks use special encapsulation to distinguish between
different VLANs.
802.1Q Frame
WIRELESS LANS
• IEEE standard 802.11 defines the specifications
for wireless LANs (WLANs).
– Support ad hoc or infrastructure topologies
AD HOC WLAN
consists of two or more wireless devices communicating
directly with each other
INFRASTRUCTURE
WIRELESS
uses a wireless device called an access point between
wireless devices and a standard cabled network.
FIREWALL SECURITY
• Firewalls protect a network from
unauthorized access.
• Firewalls use several methods to examine
network traffic for potential threats:
– Packet filtering
– Port filtering
NAT
• NAT is a routing technique that enables
computers with private IP addresses to
connect to the Internet.
• The NAT router maps private to public
addresses and vice versa.
• Security feature of NAT
– Hides hosts on private networks
NAT MAPPING METHODS
• NAT routers can map private and public
addresses using one of three methods:
– Static
• One-to-one mapping (registered to unregistered),
requiring many registered IP addresses
– Dynamic
• Many unregistered addresses mapped to one or
more registered addresses
– Overload
• Many unregistered addresses to one or more
registered addresses using ports to differentiate
connections
STATIC NAT
DYNAMIC NAT
Overload
PHYSICAL LAYER WAN
CONNECTIONS
• Physical layer WAN connections use the
following technologies:
– Leased lines
– Circuit switching
– Packet/cell switching
WAN Connection Types
 Point
to Point or dedicated connection
 Benefits:
•High speed up to 45 Mbps
• Secure
 Disadvantages:
•High expensive
•Limited availability
WAN Connection Types
Dedicated circuit path must exist between
sender and receiver for the duration of the call.
Examples:
•Dial up
•ISDN
Dial up
Benefits:
Low cost
Disadvantages:
Low speed (56Kpbs)
ISDN
ISDN
• The Integrated Services Digital Network
(ISDN) uses the PSTN network.
• Uses circuit switching technology.
• Two main types of ISDN services:
• Basic Rate Interface (BRI)
• Primary Rate Interface (PRI)
BRI
• The ISDN BRI is referred to as 2B + 1D.
• BRI has
– 2 channels for data, known as B channels
– 1 channel for control (out-of-band signaling),
known as a D channel
• Each 64-Kbps B channel can operate
independently or can be combined to
offer a 128-Kbps transmission rate.
PRI
• The ISDN PRI service consists of
– 23 channels for data, known as B channels
– 1 channel for control (out-of-band signaling),
known as a D channel
PACKET SWITCHED WAN
Benefits:
High speed up to 45 Mbps
Not Secured
Disadvantages:
Low cost
High availability
Examples:
•X.25
•Frame relay
FRAME RELAY
• Frame relay is a data-link layer protocol that
– Uses Permanent Virtual Circuit (PVC) and
Switched Virtual Circuit (SVC) connections
– Uses Data Link Control Identifier (DLCI) values to
identify connections
– Supports data rates from 56 Kbps up to 45Mbps
cell switching WAN technology
• Asynchronous Transfer Mode (ATM) is a
cell switching WAN technology.
• It is designed to carry voice, data, and
video traffic.
• ATM uses fixed 53-byte cells.
• It supports data rates from 56 Kbps up to
45Mbps
Broad band Technologies
• DSL
• CATV
• satellite
DSL
•
Digital Subscriber Line (DSL) technology offers
higher transfer rates over standard telephone
lines.
•
DSL achieves higher data rates by using higher
frequency ranges.
• Two types:
 ADSL :Asymmetric Digital Subscriber Line
Download speed more faster than upload speed
 SDSL:symmetric Digital Subscriber Line
Download speed equal upload speed
CATV
• Cable television (CATV) networks use
broadband signaling.
• Multiple channels occupy a single cable.
• CATV uses asymmetrical transmission.
CATV CONNECTION
Satellite
• Satellite uses asymmetrical transmission.
• Upload speed 512Kbps
• Download speed 2.048Mbps
• Two methods:
• One way
• Two way
WAN Encapsulation protocols
• Leased line: PPP , HDLC
• Circuit switched : PPP , HDLC
• Packet switched : X.25 , Frame relay
• Cell switched : ATM