chapter 6 - addressing the network ipv4

7/27/2019 Chapter 6 - Addressing the Network IPv4

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1

Addressing the Network

IPv4CCNA Exploration Semester 1

Chapter 6



2

IP addressing – works at

OSI model layer 3

TCP/IP model Internet layer

M Rajab - 2008

Application

Presentation

Session

Transport

Network

Data link

Physical

Application

Transport

Internet

Network Access

TCP, UDP

IP

Ethernet,

WAN

technologies

HTTP, FTP,

TFTP, SMTP

etc

Segment

Packet

Frame

Bits

Data

stream



3

Addressing topics Binary and decimal

Types of IP addresses

Assigning addresses

Network part and subnet masks

Calculating addresses

Ping and Traceroute Utilities

M Rajab - 2008



4

Binary and decimal Convert to 8-bit binary

248

187

89

Convert to decimal

00110100

01010101

11001111

M Rajab - 2008



5

248 to binary

128 64 32 16 8 4 2 1

1 1 1 1 1 0 0 0

M Rajab - 2008

248

-128120

24

-168

56

-3224

120

-6456



6

187 to binary

128 64 32 16 8 4 2 1

1 0 1 1 1 0 1 1

M Rajab - 2008

187

-12859

27

-1611

11

-83

59

-3227

3

-21



7

89 to binary

128 64 32 16 8 4 2 1

0 1 0 1 1 0 0 1

M Rajab - 2008

89

-6425

25

-169

9

-81



8

00110100 to decimal

128 64 32 16 8 4 2 1

0 0 1 1 0 1 0 0

32 16 4

M Rajab - 2008

32

+16+ 4

5252



9

01010101 to decimal

128 64 32 16 8 4 2 1

0 1 0 1 0 1 0 1

64 16 4 1

M Rajab - 2008

64

+16+ 4

+ 1

85

85



10

11001111 to decimal

128 64 32 16 8 4 2 1

1 1 0 0 1 1 1 1

128 64 8 4 2 1

M Rajab - 2008

128

+ 64

+ 8+ 4

+ 2

+ 1

207

207



11

Binary and decimal Convert to 8-bit binary

248 11111000

187 10111011

89 01011001

Convert to decimal

00110100 52

01010101 85

11001111 207

M Rajab - 2008



12

IPv4 address

192. 168. 21. 17

11000000 10101000 00010101 00010001

M Rajab - 2008

octetoctet octet octet

network part host part

255. 255. 255. 0

11111111 11111111 11111111 00000000

Prefix /24 Subnet mask:



13

Find the network address

192. 168. 21. 17

11000000 10101000 00010101 00010001

M Rajab - 2008

In a network address, all the host bits are 0.

192. 168. 21. 0

11000000 10101000 00010101 00000000

The router needs to do this for every packet.



14

Logical AND

192. 168. 21. 17

11000000 10101000 00010101 00010001

M Rajab - 2008

255. 255. 255. 0

11111111 11111111 11111111 00000000

Do a logical AND at each position

192. 168. 21. 0

11000000 10101000 00010101 00000000



15

Find the broadcast address

192. 168. 21. 17

11000000 10101000 00010101 00010001

M Rajab - 2008

In a broadcast address, all the host bits are 1.

192. 168. 21. 255

11000000 10101000 00010101 11111111

The broadcast is the last address in the network.



16

3 types of address Every network has:

Network address – the first one

Broadcast address –

the last one Host addresses – everything in between

M Rajab - 2008



17

Classful addressing

M Rajab - 2008

10. 17. 53. 60


A

172. 16. 38. 201


B

192. 168. 21. 17


C



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Classful addressing Easy to work out but very wasteful.

Routers and hosts still assume class subnet masks by

default

Class A /8 255.0.0.0

Class B /16 255.255.0.0

Class C /24 255.255.255.0

M Rajab - 2008



19

Classless addressing Any suitable prefix can be used

We (and devices) need to know what the prefix is.

More flexible, less wasteful.

M Rajab - 2008



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Classless addressing /16 172.16.0.0/16 mask 255.255.0.0

Broadcast address 172.16.255.255

Hosts 172.16.0.1 to 172.16.255.254

65534 host addresses

M Rajab - 2008

172. 16. 0. 0

10101100 00010000 00000000 00000000



21



Hosts 172.16.0.1 to 172.16.0.254

254 host addresses

M Rajab - 2008

172. 16. 0. 0

10101100 00010000 00000000 00000000



22



Hosts 172.16.0.1 to 172.16.3.254

1022 host addresses

M Rajab - 2008

172. 16. 0. 0

10101100 00010000 00000000 00000000



23

Classless addressing /26

172.16.0.0/22 mask 255.255.255.192


Hosts 172.16.0.1 to 172.16.0.62

62 host addresses

M Rajab - 2008

172. 16. 0. 010101100 00010000 00000000 00000000



24

Classless addressing /28

172.16.0.0/28 mask 255.255.255.240


Hosts 172.16.0.1 to 172.16.0.14

14 host addresses

M Rajab - 2008

172. 16. 0. 010101100 00010000 00000000 00000000



25

Calculating addresses A host has IP address 192.168.1.70/24

What is the subnet mask?

What is the network address?

What is the broadcast address?

What is the range of host addresses in the network?

M Rajab - 2008

192 168 1 70/24 fill i th



26

192.168.1.70/24 – fill in the

table

Last octet

binary

Last octet

decimal

Full

Host

Subnet mask

Network

BroadcastFirst host

Last host

M Rajab - 2008



27

192.168.1.70/24

Last octet

binary

Last octet

decimal

Full

Host 01000110 70 192.168.1.70

Subnet mask 00000000 0 255.255.255.0

Network 00000000 0 192.168.1.0

Broadcast 11111111 255 192.168.1.255First host 00000001 1 192.168.1.1

Last host 11111110 254 192.168.1.254

M Rajab - 2008



28






M Rajab - 2008

192 168 1 70/26 fill i th



29

192.168.1.70/26 fill in the

table

Last octet

binary

Last octet

decimal

Full

Host

Subnet mask

Network

BroadcastFirst host

Last host

M Rajab - 2008



30

192.168.1.70/26

Last octet

binary

Last octet

decimal

Full

Host 01000110 70 192.168.1.70

Subnet mask 11000000 192 255.255.255.192

Network 01000000 64 192.168.1.64


Last host 01111110 126 192.168.1.126

M Rajab - 2008



31






M Rajab - 2008

192 168 1 70/28 fill i th



32

192.168.1.70/28 fill in the

table

Last octet

binary

Last octet

decimal

Full

Host

Subnet mask

Network

BroadcastFirst host

Last host

M Rajab - 2008



33

192.168.1.70/28

Last octet

binary

Last octet

decimal

Full

Host 01000110 70 192.168.1.70

Subnet mask 11110000 240 255.255.255.240

Network 01000000 64 192.168.1.64


Last host 01001110 78 192.168.1.78

M Rajab - 2008



34

Unicast, Multicast, Broadcast Unicast – a message addressed to one host

Broadcast – a message addressed to all hosts on a

network. Uses network’s broadcast address or

255.255.255.255 locally

Multicast – a message addressed to a group of hosts.

Uses an address starting 224 - 239

M Rajab - 2008



35

Private IP addresses Unrestricted use on private networks. Not routed

across the Internet.

10.0.0.0 – 10.255.255.255 (10.0.0.0/8)

172.16.0.0 – 172.31.255.255 (172.16.0.0/20)

192.168.0.0 – 192.168.255.255 (192.168.0.0/24)

M Rajab - 2008



36

Public IP addresses Routed over the Internet

Master holder is IANA

Assigned to regional registries and then to ISPs

ISPs allocate them to organizations and individual

users

Use is strictly controlled as duplicate addresses are not

allowed

M Rajab - 2008



37

Special addresses 0.0.0.0 “all addresses” in default route. Hosts cannot be

given addresses starting 0.

127.0.0.1 is loopback. Hosts cannot be given

addresses starting 127.

240.0.0.0 and higher – reserved for experimental

purposes.

169.254.0.0 - 169.254.255.255 local only

192.0.2.0 to 192.0.2.255 for teaching

M Rajab - 2008



38

Network address translation A large number of hosts on a network use private

addresses to communicate with each other.

The ISP allocates one or a few public addresses.

NAT allows the hosts to share the public addresses

when they want to use the Internet

M Rajab - 2008



39

Addressing hosts Static addressing – address is configured by an

administrator

Servers, printers, routers, switches need static

addresses

Dynamic addressing – address is allocated

automatically by DHCP by leasing addresses from a

pool

Dynamic addressing is best for workstations

M Rajab - 2008



40

Blocks of addresses

Use Address range Summary

Network address 192.168.1.0 192.168.1.0/25

User hosts 192.168.1.1-127

Servers 192.168.1.128 - 191 192.168.1.128/26

Peripherals 192.168.1.192 - 223 192.168.1.192/27

Network devices 192.168.1.224 - 253 192.168.1.224/27

Router 192.168.1.254

Broadcast 192.168.1.255

M Rajab - 2008



41

Subnetting 192.168.1.0/24

M Rajab - 2008

Address 192.168.1.0 00000000

Subnet mask 255.255.255.0 00000000

Last octet binary

Borrow 1 bit from host part, give it to network part, /25

Addresses 192.168.1.0

192.168.1.128

00000000

10000000Subnet mask 255.255.255.128 10000000



42


M Rajab - 2008

Borrow 2 bits from host part, give to network part, /26


192.168.1.64

192.168.1.128192.168.1.192

00000000

01000000

1000000011000000

Subnet mask 255.255.255.192 11000000



43


M Rajab - 2008



192.168.1.32

192.168.1.64192.168.1.96

192.168.1.128

192.168.1.160

192.168.1.192192.168.1.224

00000000

00100000

0100000001100000

10000000

10100000

1100000011100000

Subnet mask 255.255.255.224 11100000



44


M Rajab - 2008


192.168.1.0

192.168.1.16

192.168.1.32

192.168.1.48192.168.1.64

192.168.1.80

192.168.1.96

192.168.1.112

192.168.1.128

192.168.1.144

192.168.1.160

192.168.1.176192.168.1.192

192.168.1.208

192.168.1.224

192.168.1.240

00000000

00010000

00100000

0011000001000000

01010000

01100000

01110000

10000000

10010000

10100000

1011000011000000

11010000

11100000

11110000

Subnet mask 255.255.255.240 11110000

And so on…



45

Subnetting 192.168.1.0/24 Every time you borrow another bit you:

Double the number of subnets

Halve the size of the subnets

Each subnet has a network address, a broadcast

address, and everything in between is a host address.

Here are some ways of visualising the process.

M Rajab - 2008



46


M Rajab - 2008

Bits borrowed 1 2 3 4 5 6

No of networks 2 4 8 16 32 64

Prefix /25 /26 /27 /28 /29 /30

Bit value/

network size

128 64 32 16 8 4

No of hosts 126 62 30 14 6 2

Subnet mask 128 192 224 240 248 252



47

Address space Make a spreadsheet or table with numbers 0 to 255

Link to show table

M Rajab - 2008

http://localhost/var/www/apps/conversion/tmp/scratch_10/SubnettingVisual.ppt

http://localhost/var/www/apps/conversion/tmp/scratch_10/SubnettingVisual.ppt



48

Subnet chart

M Rajab - 2008



49

Subnetting There are many subnet calculators, but you will not be

able to use them in exams.

Start with the biggest subnet and work down to the

smallest.

Make sure the subnets are valid sizes with valid subnet

masks.

Make sure that there are no overlaps.

M Rajab - 2008



50

Ping and traceroute Ping sends an ICMP message. If all is well, the

destination replies. If not, a router may reply to say the

destination is unreachable, or the ping may time out.

Traceroute sends a series of messages so that eachrouter along the path replies. You get a list of

addresses of all the routers.

M Rajab - 2008



51

IPv6 Development started in 1990s because of concerns

about IPv4 addresses running out

A whole new protocol suite – not just layer 3

Uses 128-bit hierarchical addressing, written using

hexadecimal

Simpler header

Integrated security – authentication, privacy

Quality of service mechanisms

M Rajab - 2008



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chapter 6 - addressing the network ipv4

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