CCNA2 mod6

© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1

Addressing the network IPv4

CCNA Exploration Semester 1 – Chapter 6


IP addressing – works at

OSI model layer 3

TCP/IP model Internet layer

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


Addressing topics

Binary and decimal

Types of IP addresses

Assigning addresses

Network part and subnet masks

Calculating addresses

Ping and Traceroute Utilities


Binary and decimal

Convert to 8-bit binary

248

187

89

Convert to decimal

00110100

01010101

11001111


248 to binary

128 64 32 16 8 4 2 1

1 1 1 1 1 0 0 0

248-128120

24-16

8

56-3224

120-6456


187 to binary

128 64 32 16 8 4 2 1

1 0 1 1 1 0 1 1

187-128

59

27-1611

11-83

59-3227

3-21


89 to binary

128 64 32 16 8 4 2 1

0 1 0 1 1 0 0 1

89-6425

25-16

9

9-81


00110100 to decimal

128 64 32 16 8 4 2 1

0 0 1 1 0 1 0 0

32 16 4

32 +16+ 452

52


01010101 to decimal

128 64 32 16 8 4 2 1

0 1 0 1 0 1 0 1

64 16 4 1

64 +16+ 4+ 185

85


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

128+ 64 + 8+ 4+ 2+ 1207

207


Binary and decimal

Convert to 8-bit binary

248 11111000

187 10111011

89 01011001

Convert to decimal

00110100 52

01010101 85

11001111 207


IPv4 address

192. 168. 21. 17

11000000 10101000 00010101 00010001

octetoctet octet octet

network part host part

255. 255. 255. 0

11111111 11111111 11111111 00000000

Prefix /24 Subnet mask:


Find the network address

192. 168. 21. 17

11000000 10101000 00010101 00010001

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.


Logical AND

192. 168. 21. 17

11000000 10101000 00010101 00010001

255. 255. 255. 0

11111111 11111111 11111111 00000000

Do a logical AND at each position

192. 168. 21. 0

11000000 10101000 00010101 00000000


Find the broadcast address

192. 168. 21. 17

11000000 10101000 00010101 00010001

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.


3 types of address

Every network has:

Network address – the first one

Broadcast address – the last one

Host addresses – everything in between


Classful addressing

10. 17. 53. 60


A

172. 16. 38. 201


B

192. 168. 21. 17


C


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


Classless addressing

Any suitable prefix can be used

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

More flexible, less wasteful.


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

172. 16. 0. 0

10101100 00010000 00000000 00000000



172.16.0.0/24 mask 255.255.255.0


Hosts 172.16.0.1 to 172.16.0.254

254 host addresses

172. 16. 0. 0

10101100 00010000 00000000 00000000



172.16.0.0/22 mask 255.255.252.0


Hosts 172.16.0.1 to 172.16.3.254

1022 host addresses

172. 16. 0. 0

10101100 00010000 00000000 00000000



172.16.0.0/22 mask 255.255.255.192


Hosts 172.16.0.1 to 172.16.0.62

62 host addresses

172. 16. 0. 0

10101100 00010000 00000000 00000000



172.16.0.0/28 mask 255.255.255.240


Hosts 172.16.0.1 to 172.16.0.14

14 host addresses

172. 16. 0. 0

10101100 00010000 00000000 00000000



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?


192.168.1.70/24 – fill in the table

Last octet binary Last octet decimal

Full

Host

Subnet mask

Network

Broadcast

First host

Last host


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 255 192.168.1.255

First host 00000001 1 192.168.1.1

Last host 11111110 254 192.168.1.254









192.168.1.70/26 fill in the table

Last octet binary

Last octet decimal

Full

Host

Subnet mask

Network

Broadcast

First host

Last host


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

Broadcast 01111111 127 192.168.1.127

First host 01000001 65 192.168.1.65

Last host 01111110 126 192.168.1.126









192.168.1.70/28 fill in the table

Last octet binary

Last octet decimal

Full

Host

Subnet mask

Network

Broadcast

First host

Last host


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

Broadcast 01001111 79 192.168.1.79

First host 01000001 65 192.168.1.65

Last host 01001110 78 192.168.1.78


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


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)


Public IP addresses

Routed over the Internet

Master holder is IANA

Assigned to regional registries and then to ISPs

ISPs allocate them to organisations and individual users

Use is strictly controlled as duplicate addresses are not allowed


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


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


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


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


Subnetting 192.168.1.0/24

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 192.168.1.0192.168.1.128

0000000010000000

Subnet mask 255.255.255.128 10000000



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

Addresses 192.168.1.0192.168.1.64192.168.1.128192.168.1.192

00000000010000001000000011000000

Subnet mask 255.255.255.192 11000000



Borrow 3 bits from host part, give to network part, /27

Addresses 192.168.1.0192.168.1.32192.168.1.64192.168.1.96192.168.1.128 192.168.1.160 192.168.1.192 192.168.1.224

0000000000100000010000000110000010000000101000001100000011100000

Subnet mask 255.255.255.224 11100000



Borrow 4 bits from host part, give to network part, /28192.168.1.0192.168.1.16192.168.1.32192.168.1.48192.168.1.64192.168.1.80192.168.1.96192.168.1.112

192.168.1.128192.168.1.144192.168.1.160192.168.1.176 192.168.1.192192.168.1.208192.168.1.224192.168.1.240

0000000000010000001000000011000001000000010100000110000001110000

1000000010010000 1010000010110000 1100000011010000 1110000011110000

Subnet mask 255.255.255.240 11110000

And so on…



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.



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


Address space

Make a spreadsheet or table with numbers 0 to 255

Link to show table


Subnet chart


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.


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 each router along the path replies. You get a list of addresses of all the routers.


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


Subnetting - visual

CCNA Exploration Semester 1

Chapter 6


Prefix /24

Three octets in network part, last octet in host part.

All possible numbers 0 – 255 in last octet belong in the same network.

Network address yellowBroadcast address blue

Subnet mask 255.255.255.0


Prefix /25

First bit of fourth octet taken into network part.

For every bit taken, double number of networks, halve their size.


Subnet mask 255.255.255.128


Prefix /26

2 bits of fourth octet taken into network part.



Subnet mask 255.255.255.192


Prefix /27




Subnet mask 255.255.255.224


Prefix /28




Subnet mask 255.255.255.240


Prefix /29




Subnet mask 255.255.255.248


Prefix /30




Subnet mask 255.255.255.252


Variable length

Networks do not need to be all the same size.

/27

/26

/25


Summary Hierarchical Design model addresses performance,

scalability, maintainability & manageability issues.

Traffic Analysis is used to monitor network performance.

Hierarchical Design Model is composed of 3 layers:Access

Distribution

Core

Switches selected for each layer must meet the needs of each hierarchical layer as well as the needs of the business.


Labs & Activities

Type Detail

PT 1.2.4 Mandatory*

Lab 1.3.1 Mandatory

PT 1.3.2 Mandatory

Lab 1.3.3 Review carefully

* If no previous Packet Tracer experience, else strongly recommended


Documents

CCNA2 mod6