Training Course on Network Administration

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Training Course on Network

Administration

03 -07, March 2014

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Course Outline

Day-1

•Exploring Networking world.

•Network Communication Models.

•OSI and TCP/IP Architecture.

•Application Layer

•Transport Layer

• Day-2

• Network Layer

•IP addressing and Planning

•Data Link Layer

Day-3 •Switched Networks •VLANs •Routing •Inter-VLAN Routing • Day-4 •Dynamic Routing •RIP •OSPF • Day-5

•Access Control Lists

•Network Address Translation

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About Course

Theoretical portion of this course is customized version

of Cisco curriculum, where many different topics are

added.

First two days will cover the Fundamental concepts of

Networking, which will be mostly theoretical.

Remaining Three days will include lectures along with

hand on labs to give practical experience.

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Exploring the Network

(5)

Interconnecting our Lives

Networks in Our Past and Daily Lives

(6)

Networking impacts in our daily lives

Communicate

Work

Play

Learn

(7)

Converged Networks

Traditional Service Networks

(8)

Current Service Networks

(9)

Reliable Network

Supporting Network Architecture

As networks evolve, we are discovering that there are

four basic characteristics that the underlying

architectures need to address in order to meet user

expectations:

Fault Tolerance

Scalability

Quality of Service (QoS)

(10)

Fault Tolerance in Circuit Switched Network

(11)

Fault Tolerance in Packet Switched Network

(12)

Scalability

(13)

Quality of Service (QoS)

(14)

Network Security

(15)

LANs, WANs, and Internets

Components of a Network

There are three categories of network components:

End devices

Intermediary devices

(16)

Network Representations

(17)

Components of a Network

Network Topology Diagrams

Components of a Network

(18)

LANs and WANs

Types of Networks

LANs and WANs

Types of Networks

The two most common types of network infrastructures

are:

Local Area Network (LAN)

Wide Area Network (WAN).

Other types of networks include:

Metropolitan Area Network (MAN)

Wireless LAN (WLAN)

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LANs and WANs

(20)

The Internet

(21)

Connecting to the Internet

Connecting Businesses to the Internet

Connecting to the Internet

(22)

Network Trends

New trends

Network Trends

New trends

Some of the top trends include:

Bring Your Own Device (BYOD)

Online collaboration

Video

(23)

Network Trends

Bring Your Own Device (BYOD)

Network Trends

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Network Trends

Online Collaboration and Considerations

Network Trends

(25)

Network Trends

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Network Trends

Cloud Computing

Network Trends

Cloud Computing

.

Cloud Computing

- Cloud computing is the use of computing resources

(hardware and software) that are delivered as a service over a network.

•A company uses the hardware and software in the cloud and a service

fee is charged

.

(27)

Network Trends

Data Centers - Cloud computing is possible because of data centers. A

data center is a facility used to house computer systems and associated components including:

Redundant data communications connections

Redundant storage systems (typically uses SAN technology) Redundant or backup power supplies

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Network Protocols and

Communications

Network Protocols and

Communications

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Protocols

Network Communications

Protocols

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Rules of Communications

Establishing Rules

Rules of Communications

Establishing Rules

Protocols in human communications account for the

following requirements:

An identified sender and receiver Common language and grammar Speed and timing of delivery

Confirmation or acknowledgement requirements

Common computer protocols include:

Message encoding

Message formatting and encapsulation Message size

Message timing

(31)

How network are designed and built?

Networks are complex

with many pieces of

Hosts, routers, links, applications, protocols,

hardware, software.

Can we organize it, somehow?

Let’s consider a Web page request:

Browser requests Web page from server

Server should determine if access is privileged

Reliable transfer page from server to client

(32)

Organization of air travel

a series of steps

ticket (purchase)

baggage (check)

gates (load)

runway takeoff

airplane routing

ticket (complain)

baggage (claim)

gates (unload)

runway landing

airplane routing

(33)

ticket (purchase) baggage (check) gates (load) runway (takeoff) airplane routing departure airport arrival airport intermediate air-traffic control centers

airplane routing airplane routing

ticket (complain) baggage (claim gates (unload) runway (land) airplane routing ticket baggage gate takeoff/landing airplane routing

Layering of airline functionality

layers:

each layer implements a service

(34)

Reference Models

Network Layered Model

Reference Models

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OSI Model

Initially the OSI model was designed by the ISO to provide a framework

on which to build a suite of open systems protocols.

Ultimately, the speed at which the TCP/IP-based Internet was adopted,

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TCP/IP Model

Alternative model.

The architecture of the TCP/IP protocol suite follows

the structure of this model.

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Peer-to-Peer Communications

Routers Switches/NICs Repeaters, Hubs, Cables, etc. Hosts (all layers) Hosts (all layers) Routers Switches/NICs Repeaters, Hubs, Cables, etc.

(38)

Communicating the Messages

Better approach – segmentation.

Multiplexing:

Different conversations can be interleaved.

Segmentation

00101 0 00101 0 00101 0 00101 0 00101 0 00101 0

(39)

Disadvantage of Segmentation

Disadvantage – added level of complexity.

(40)

Data Encapsulation

Transport Data-Link Physical Network Upper-Layer Data Upper-Layer Data TCP Header Data IP Header Data LLC Header 0101110101001000010 Data MAC Header Presentation Application Session

Segmen

Packet

Bits

Frame

PDU

FCS FCS

(41)

The Communication Process - Encapsulation

Server

Data

HTTP Header TCP Header IP Header Data Link Header Data Link Trailer HTTP Data

(42)

The Communication Process - Decapsulation

Decapsulation – Process of removing control information as it passes

upwards through the layered model.

Data HTTP Header TCP Header IP Header Data Link Header Data Link Trailer Client HTTP Data

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Devices and their layers

Hosts and servers operate at Layers 2-7; they perform the

encapsulation process.

Routers: Layers 1 through 3, make decisions at layer 3

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Data Flow Through a Network

(45)

Accessing Local Resources

Network Address

zContains information required to deliver the IP packet from the source

device to the destination device.

zHas two parts, the network prefix and the host part.

(46)

Accessing Local Resources

Data Link Address

zDifferent role.

zThe purpose of the data link address is to deliver the data link frame

from one network interface to another network interface on the same network.

zIP packet encapsulated in a data link frame so it can be transmitted

over the physical medium, the actual network.

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Accessing Local Resources

Data Link Address

zThe source and destination data link addresses are added:

ySource data link address - The physical address of the device that

is sending the packet.

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Communicating on same Network

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Learning the MAC Address

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Accessing Remote Devices

(51)

Accessing Remote Devices

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Accessing Remote Resources

Using Wireshark to View Network Traffic

Accessing Remote Resources

(53)

Application Layer

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The TCP/IP Application Layer

There are many TCP/IP application layer protocols and

new protocols are always being developed.

HTTP– Hypertext Transfer Protocol DNS- Domain Name System SMTP- Simple Mail Transfer Protocol

POP - Post Office Protocol IMAP - Internet Message Access Protocol

FTP - File Transfer Protocol TFTP - Trivial File Transfer Protocol DHCP- Dynamic Host Configuration Protocol

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Two Networking Models

Networked computers take on different roles or

functions in relation to each other.

(56)

HTTP (WWW) FTP SMTP (email) Telnet (file transfer) (remote login) DHCP (IP address resolution) DNS (file sharing) P2P (domain name resolution) (file sharing) SMB We will examine HTTP in detail.

Application Layer Protocols

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Data

HTTP Header TCP Header IP Header Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer

Reminder of encapsulation/decapsulation

(58)

Focus on Application Header and/or Data

We will examine how the application (header) and/or data

communication with each other between the client and the server.

“Later” we will look at what roles the other layers, protocols (TCP, IP,

HTTP

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HTTP (Hypertext Transfer Protocol)

HTTP – The Web’s application layer protocol.

Implemented in Client/ Server Model

Client-Request Web objects (Browser)

Server-Send objects in response to request (Web Server)

RFC 1945---HTTP 1.0

NCP HTTP Server HTTP Client

HTTP RESPONSE HTTP REQUEST

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HTTP (Hypertext Transfer Protocol)

Web page (also called a html document)

Web page consists of objects

Objects (examples): HTML file JPEG image GIF image JAVA applet Audio file z <html> z <head>

z <title>NCP-Centre of Excellence, National Centre for Physics,Islamabad,Pakistan</title>

z </head>

z <body topmargin="0" leftmargin="0" rightmargin="0" style="text-align: left">

z <table border="0" cellpadding="0" style="border-collapse: collapse" bordercolor="#111111" width="99%" id="AutoNumber1" height="373">

z <tr>

z <td width="79%" height="105" colspan="4">

z <img border="0" src="images/Banner.jpg" width="100%" height="120"></td>

z </tr>

The base HTML file references

other objects in the page.

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HTTP Request Message

Request Message Request line Header lines GET /index.html / HTTP/1.1 Accept-Language: en-us

User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506; InfoPath.1)

Host: www.ncp.edu.pk Connection: Keep-Alive

HTTP Client HTTP

Server

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HTTP Request Message

Request Line

GET - Browser/client is requesting an object

/index.html/ - Browser is requesting this object in this

directory (default is index.html)

HTTP/1.1 - Browser implements the HTTP/1.1 (1.1 is

backwards compatible with 1.0)

GET /index.html/ HTTP/1.1 Accept-Language: en-us

Host: www.cabrillo.edu Connection: Keep-Alive

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HTTP Request Message

Request Line

GET: - Used by browser/client to request an object.

POST: - Used when user has filled out a form and sending

information to the server. (Forms do not have to use POST.)

- Example: words in a search engine

HEAD: - Similar to a GET, but the server will responds with a GET /~rgraziani/ HTTP/1.1

Accept-Language: en-us

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HTTP Request Message

Header Lines

Accept-Language:- User prefers this language of the object

User-Agent: - The browser type making the request

Host: - Host on which the object resides

Connection: - Client/browser is telling the server to keep

this TCP connection Open, known as a persistent connection.

- We will talk about this later in TCP

(transport layer)

GET /~rgraziani/ HTTP/1.1 Accept-Language: en-us

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HTTP Response Message

HTTP/1.1 200 OK

Date: Fri, 22 Feb 2008 16:34:18 GMT Server: Apache/2.0.52 (Red Hat)

Last-Modified: Thu, 15 Nov 2007 19:33:12 GMT Content-Length: 15137

Connection: close

Content-Type: text/html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.ncp.edu.pk/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.ncp.edu.pk/1999/xhtml">

(66)

HTTP Response Message

HTTP/1.1 200 OK

Date: Fri, 22 Feb 2008 16:34:18 GMT Server: Apache/2.0.52 (Red Hat)

Last-Modified: Thu, 15 Nov 2007 19:33:12 GMT Content-Length: 15137

Connection: close

Content-Type: text/html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.ncp.edu.pk/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.ncp.edu.pk/1999/xhtml">

z

Response message:

y

Status line

y

Header lines

y

Entity body

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Telnet

Server

(68)

Telnet

Allows a user to remotely access another device (host, router, switch).

A connection using Telnet is called a Virtual Terminal (VTY) session, or

connection.

Telnet uses software to create a virtual device that provides the same

features of a terminal session with access to the server command line interface (CLI). Telnet clients: Putty Teraterm

Server

Telnet

(69)

Telnet

Telnet supports user authentication, but does not encrypt data.

All data exchanged during a Telnet sessions is transported as plain text.

Secure Shell (SSH) protocol offers an alternate and secure method for

server access.

Stronger authentication Encrypts data

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Common Application Layer Protocols

SMTP and POP

Common Application Layer Protocols

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Everyday Application Layer Protocols

SMTP and POP (Continued)

Everyday Application Layer Protocols

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DNS – Domain Name System

DNS allows users (software) to use domain names instead of IP

(73)

Name Resolution

Resolver

DNS client programs used to look up DNS name information.

Name Resolution

The two types of queries that a DNS resolver (either a DNS client or

another DNS server) can make to a DNS server are the following: Recursive queries

Need the IP

address

(74)

DNS Name Resolution

User types http://www.example.com

Step 1.

The DNS resolver on the DNS client sends a recursive query to its

configured Local DNS server.

Requests IP address for "www.example.com".

The DNS server for that client is responsible for resolving the name

Cannot refer the DNS client to another DNS server.

(75)

Step 2.

Local DNS Server forwards the query to a Root DNS server.

Step 3.

Root DNS server

Makes note of .com suffix

DNS Name Resolution

1

2 ₂

(76)

DNS Name Resolution

Root DNS Servers

There are 13 Root DNS servers (labeled A through M)

TLD Servers

Responsible for domains such as .com, edu, org, .net, .uk, jp, fr Network Solutions maintains TLD servers for .com

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Step 4.

The local DNS server sends query for www.example.com to one of the

TLD servers. Step 5. TLD Server

DNS Name Resolution

4 ₄ 5

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Step 6.

Local DNS server sends query for www.example.com directly to DNS

server for example.com Step 7.

example.com DNS server responds with its IP address for

www.example.com 6 6

DNS Name Resolution

7

(79)

Step 8.

Local DNS server sends the IP address of www.example.com to the

DNS client. DNS Caching

When a DNS server receives a DNS reply (mapping hostname to an IP

address) it can cache the information in its local memory.

8

7

DNS Name Resolution

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DNS Name Resolution

In the worst cases, you'll get a

dialog box that says the domain name doesn't exist - even though you know it does.

This happens because the

authoritative server is slow replying to the first, and your computer gets tired of waiting so it times-out (drops the connection) or the domain name does not exist.

But if you try again, there's a good

chance it will work, because the

authoritative server has had enough time to reply, and your name server has stored the information in its

(81)

nslookup

(82)

DNS Name

Resolution

DNS Name

Resolution

ipconfig /displaydns

After a certain amount of time, specified in the Time to Live (TTL)

associated with the DNS resource record, the resolver discards the record from the cache.

ipconfig /flushdns – Manually deletes entries

The default TTL for positive responses is 86,400 seconds (1 day).

(83)

Providing IP Addressing Services

Dynamic Host Configuration Protocol

DHCP allows a host to

obtain an IP address

dynamically

• DHCP Information can include: •IP address •Subnet mask •Default gateway •Domain name •DNS Server

• DHCP servers can be:

•Server on LAN

•Router

(84)

DHCP Operation

(85)

DHCP – Dynamic Host Configuration Protocol

(86)

Providing File Sharing Services

File Transfer Protocol

FTP allow data

transfers between a

client and a server

FTP client is an

application that runs

on a computer that is

used to push and pull

data from a server

running an FTP

daemon

To successfully

transfer data, FTP

requires two

connections between

the client and the

server, one for

commands and

replies, the other for

the actual file transfer

(87)

Server Message Block

Clients

establish a

long term

connection to

servers

After the

connection is

established,

the user can

access the

resources on

the server as if

(88)

Server Message Block

(89)

Transport Layer

(90)

Transport Layer

(91)

Encapsulation

S.P / D.P. / S.N. / Ack # / … DATA

DATA

IPv / HLEN / Flag / S. IP / D. IP / … DATA (SEGMENT) Frame Header DATA (PACKET) Trailer

SEGMENT

PACKET

(92)

Data

HTTP Header TCP Header IP Header Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer IP Packet Data Link Header Data Link Trailer

Data

HTTP Header TCP Header IP Header Data Link Header Data Link Trailer

Reminder of encapsulation/decapsulation

(93)

Focus on Transport Layer

TCP

(94)

1. Tracking the individual communication between applications on the source and destination hosts

2. Segmenting data for manageability and reassembling segmented

data into streams of application data at the destination

3. Identifying the proper application for each communication stream

www.ncp.edu.pk

TCP Segment

Transport Layer Responsibility

(95)

Transport Layer Protocols

TCP/IP uses two transport layer protocols:

Transmission Control Protocol (TCP)

• Provides reliable delivery ensuring that all of the data arrives at the destination.

• Uses acknowledged delivery and other processes to ensure delivery. • Makes larger demands on the

network – more overhead.

• User Datagram Protocol (UDP)

• Provides just the basic functions for delivery – no reliability.

(96)

Introducing TCP and UDP

TCP and UDP

TCP

UDP

0 15 16 31

16-bit Source Port Number 16-bit Destination Port Number

32-bit Sequence Number

32 bit Acknowledgement Number 4-bit Header Length 6-bit (Reserved) U R G A C K P S H R S T S Y N F I

N 16-bit Window Size 16-bit TCP Checksum 16-bit Urgent Pointer

Options (if any)

(97)

Introducing TCP

Transmission Control Protocol (TCP)

RFC 793

Connection-oriented – creating a session between

source and destination

Reliable delivery – retransmitting lost or corrupt

data

Ordered data reconstruction – numbering and

sequencing of segments

Flow control - regulating the amount of data

transmitted

(98)

Introducing UDP

User Datagram Protocol (UDP)

RFC 768

Connectionless

Unreliable delivery

No ordered data

reconstruction

No flow control

Stateless protocol

Applications that use UDP:

Domain Name System (DNS)

Video Streaming

(99)

Separating Multiple Communications

Port Numbers are used by TCP and UDP to differentiate between

applications.

(100)

TCP and UDP Port Addressing

(101)

TCP and UDP Port Addressing

Netstat

Used to examine TCP connections that are open

and running on a networked host

(102)

TCP Communication

TCP Server Processes

(103)

TCP Connection, Establishment and

Termination

TCP Connection, Establishment and

Termination

Three-Way Handshake

Establishes that the destination device is present

on the network

Verifies that the destination device has an active

service and is accepting requests on the

destination port number that the initiating client

intends to use for the session

Informs the destination device that the source

client intends to establish a communication

session on that port number

(104)

TCP Three-Way Handshake – Step 1

Step 1: The initiating client requests a

client-to-server communication session with the client-to-server.

(105)

TCP Three-Way Handshake – Step 2

Step 2: The server acknowledges the

client-to-server communication session and requests a

server-to-client communication session.

(106)

TCP Three-Way Handshake – Step 3

Step 3: The initiating client acknowledges the

server-to-client communication session.

(107)

Protocol Data Units??? Is this correct title??

TCP Reliability – Ordered Delivery

Protocol Data Units??? Is this correct title??

TCP Reliability – Ordered Delivery

Sequence numbers used to reassemble segments

into original order

(108)

TCP Reliability – Acknowledgement and

Window Size

TCP Reliability – Acknowledgement and

Window Size

The sequence number and acknowledgement

number are used together to confirm receipt.

Window Size -

The amount of data that a source can

(109)

Protocol Data Units

TCP Reliability and Flow Control

Data Loss and Retransmission

When TCP at the source host has not received an

acknowledgement after a predetermined amount of time, it

will go back to the last acknowledgement number that it

received and retransmit data from that point forward

Flow Control

Uses the window size field in the TCP header to specify the

amount of data that can be transmitted before an

acknowledgement must be received.

Adjusts the effective rate of data transmission to the

maximum flow that the network and destination device can

support without loss.

(110)

TCP Flow Control – Congestion Avoidance

(111)

TCP and UDP

TCP Reliability - Acknowledgements

TCP and UDP

TCP Reliability - Acknowledgements

TCP uses a combination of sequence numbers and

acknowledgements to ensure all requested data

has been received.

Can be inefficient when there is loss of one or

more segments

Selective Acknowledgements (SACK) –

implementation of TCP that overcomes the

inefficiency of TCP acknowledgements

(112)

UDP Communication

UDP Low Overhead vs. Reliability

UDP

Simple protocol that provides the basic transport layer

function

Used by applications that can tolerate small loss of data

Used by applications that cannot tolerate delay

Used by

Domain Name System (DNS)

Simple Network Management Protocol (SNMP)

Dynamic Host Configuration Protocol (DHCP)

Trivial File Transfer Protocol (TFTP)

IP telephony or Voice over IP (VoIP)

(113)

Datagram Reassembly

(114)

UDP Server and Client Processes

UDP-based server applications are assigned

well-known or registered port numbers.

UDP client process randomly selects port number

from range of dynamic port numbers as the source

port.

(115)

TCP or UDP

Applications that use TCP

TCP or UDP

(116)

TCP or UDP

Applications that use UDP

TCP or UDP

(117)

Training Course on Network Administration