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COMPUTER NETWORK
ARCHITECTURES
Navpreet Singh
Computer Centre
Indian Institute of Technology Kanpur
Kanpur INDIA
(Ph : 2597371, Email : [email protected])
Content
Content
Introduction to Computer Networks
Overview Of Network Architectures
Campus Networks
Residential Networks
Enterprise Networks
Internet
How Web Works
Network & Internet Security
Introduction to Computer Networks
Computer Networks
Computer
network
connects two or more
autonomous computers.
The computers can be
geographically located
anywhere.
Introduction to Computer Networks
LAN, MAN & WAN
Network in small geographical Area (Room, Building
or a Campus) is called LAN (Local Area Network)
Network in a City is call MAN (Metropolitan Area
Network)
Network spread geographically (Country or across
Globe) is called WAN (Wide Area Network)
Introduction to Computer Networks
Applications of Networks
Resource Sharing
Hardware (computing resources, disks, printers)
Software (application software)
Information Sharing
Easy accessibility from anywhere (files, databases)
Search Capability (WWW)
Communication
Email, Chat, VoIP
Message broadcast
Remote computing
Distributed processing (GRID Computing)
Introduction to Computer Networks
Network Components
Physical Media
Interconnecting Devices
Computers
Networking Software
Applications
Introduction to Computer Networks
Networking Media
Networking media can
be defined simply as
the means by which
signals (data) are sent
from one computer to
another (either by cable
or wireless means).
Introduction to Computer Networks
Networking Devices
HUB, Switches, Routers,
Wireless Access Points,
Modems etc.
Introduction to Computer Networks
Computers: Clients and Servers
In
a
client/server
network arrangement,
network services are
located in a dedicated
computer whose only
function is to respond
to the requests of
clients.
The server contains the
file, print, application,
security,
and
other
services in a central
computer
that
is
continuously available
to respond to client
requests.
Introduction to Computer Networks
Networking Protocol: TCP/IP
Introduction to Computer Networks
Applications
E-mail
Searchable Data (Web Sites)
E-Commerce
News Groups
Internet Telephony (VoIP)
Video Conferencing
Chat Groups
Instant Messengers
Internet Radio
Campus Networks
Campus LAN Technology Options
Ethernet
Fast Ethernet
Gigabit Ethernet
10 Gig Ethernet
WLAN
Campus Network
Campus Network Architecture
Server
Farm
Firewall
Backbone Switch
Distribution Switch
Access Switch
Router
Internet
Campus Network
Campus Network Architecture
Uses Three Tier Switching Architecture (Popularly known as
Cisco’s Switching Architecture)
Backbone Switch
Layer 3/4 Chassis based switch
Multiple 100Fx or 1000SX/LX or 10GLX/LH ports for
connectivity to Distribution switches
Multiple 10/100/1000 ports for connectivity to Servers
Distribution Switch
Layer 2/3 Managed Fixed configuration switch
1/2 100Fx or 1000Sx/Lx or 10GLX/LH ports for connectivity to
the Backbone switch
Multiple 10/100 or 10/100/1000 ports for connectivity to the
Access switches
Access Switch
Layer2 Managed/Unmanaged Fixed configuration switch
Multiple 10/100 or 10/100/1000 ports for desktop connectivity
MAN Technologies
Residential Networks: Dial-up
Uses POTS (Plain Old Telephone System)
Provides a low cost need based access.
Bandwidth 33.6 /56 Kbps.
On the Customer End: Modem is connected to a
Telephone Line
On the Service Provider End: Remote Access Server
(RAS) is connected to Telephone Lines (33.6 Kbps
connectivity) or E1/R2 Line (56 Kbps connectivity)
RAS provide dialin connectivity, authentication and
metering.
Achievable bandwidth depends on the line quality.
MAN Technologies
Residential Networks: Dial-up
RAS
MAN Technologies
Residential Networks: DSL
Digital Subscriber Line (DSL) uses the Ordinary
Telephone line and is an always-on technology. This
means there is no need to dial up each time to
connect to the Internet.
Because DSL is highly dependent upon noise levels,
a subscriber cannot be any more than 5.5 kilometers
(2-3 miles) from the DSL Exchange
Service can be symmetric, in which downstream and
upstream speeds are identical, or asymmetric in
which downstream speed is faster than upstream
speed.
DSL comes in several varieties:
Asymmetric DSL (ADSL)
High Data Rate DSL (HDSL)
Symmetric DSL (SDSL)
Very High Data Rate DSL (VDSL)
MAN Technologies
Residential Broadband: ADSL
MAN Technologies
Residential Broadband: Mobile
Wireless
Use CDMA (128 Kbps) or GSM GPRS (384 Kbps)
Mobile Wireless
Enterprise Network
Enterprise WAN Network
Enterprise Network
Enterprise WAN Network
Enterprise Network
Enterprise WAN Network
Server
Farm
Corporate Head Office
Branch Office
Service Provider
Network
Branch Office
All the locations are connected through a Service Provider Network
over MPLS Backbone
Branch Office
Internet
Internet
ISP
networ
k
ISP
networ
k
Backbone
ISP Networks
Bandwidth-limited
links
ISP
network
Customer Networks
• Customers connect to
a National ISP
• National ISPs connect
to International
Backbone Networks
Service Provider Network
Service Provider Networks: Reliance
Service Provider Network
Service Provider Networks: Reliance
Reliance Data Centers, are connected to 132 countries across 4
continents spanning US, UK, Mid-east and Asia-Pac through Flag
Telecom backbone (Reliance Infocomm 's group company) and other
undersea cable systems like Se-Me-Wea-3 and i2i and are having
public / private peering relationship with large Tier 1 ISPs and
content providers at more than 15 Internet Exchange points across
the globe. There also exists peering relationship with other popular
domestic ISPs on STM-1 bandwidth levels.
The data centers further are connected to Reliance's country wide
optic fiber based IP network with terabytes of capacity having points
of presence at more than 1100 cities. Customers' can access the
Internet by connecting to any of these 1100 PoPs using multiple
means like local dedicated leased lines, PSTN -ISDN dialup links OR
simply by using Reliance's 3G CDMA mobile services.
The Reliance Data Centers at various locations are also
interconnected through redundant fiber ring with bandwidth capacity
of STM-4 for data replication purposes for providing Disaster
Recovery services.
Service Provider Network
Service Provider Networks: FLAG
Service Provider Network
Service Providers
National Service Providers:
VSNL
Reliance
BSNL
Bharti
Satyam
International Service Providers (connecting India to
the World)
Flag
SingTel
NIXI (STPI Delhi, Mumbai, Kolkata & Chennai)
provides peering connectivity between Indian ISPs
WWW
How Web Works?
Let's say you want to visit
the google website.
First you enter the address
or URL of the website in
your web browser.
Then
your
browser
requests the DNS Server to
get the IP address of the
web server
WWW
How Web Works?
Then
your machine
sends an HTTP request to
the web server that hosts
the google site.
The server sends the data
over the Internet to your
computer.
Your
web
browser
interprets
the
data,
displaying it on your
computer screen.
DNS
DNS Resolution
DNS is a network service that enables clients to resolve
names to IP address.
A DNS server maintains the name to IP address mapping
of the domain for which it is the name server
The DNS server for a domain is registered with the
domain registrar and the entry is maintained by the rootservers.
Whenever a DNS for a server is queried, the root servers
are contacted.
The root servers replies with the IP address of the DNS
server of the domain (for higher level domains) or
forwards the request to the country root servers (four
country specific domains).
DNS
Load Balancing
DNS supports Load Balancing: The same name
resolves to multiple IP Addresses (IP addresses of
different Mirrored servers).
Companies like akamai provide "Enhanced DNS"
services:
Different DNS results based on source IP.
Web browser could automatically be directed to the closest
web server thus reducing the download time
Companies like akamai maintain mirror sites of
many organizations on their server and direct
request for these sites to the nearest server.
INTERNET Security
INTERNET SECURITY
INTERNET Security
INTERNET Security Threats
Hacking
DoS
Reconnaissance
Malwares
Mail SPAM
Phishing
Botnets
INTERNET Security
Prevention Techniques
Some of the prevention tools include:
Network Firewall
Host Firewall
IDS/IPS
Mail Antispam and Antivirus Appliances
UTM Appliances
Application and OS Hardening
INTERNET Security
WLAN Security