1. Addressing the Network IPv4
4/11/2017
Addressing the Network IPv4
CCNA Exploration Semester 1
Chapter 6
S Ward Abingdon and Witney College

2. 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
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3. Addressing topics Binary and decimal Types of IP addresses
Assigning addresses
Network part and subnet masks
Calculating addresses
Ping and Traceroute Utilities
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4. Binary and decimal Convert to 8-bit binary 248 187 89
Convert to decimal
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5. 248 to binary
128 64 32 16 8 4 2 1
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6. 187 to binary
128 64 32 16 8 4 2 1
3 -2 1
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7. 89 to binary
128 64 32 16 8 4 2 1
9 -8 1
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8. to decimal
128 64 32 16 8 4 2 1 52
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9. to decimal
128 64 32 16 8 4 2 1 85
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10. to decimal
128 64 32 16 8 4 2 1
207
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11. Binary and decimal Convert to 8-bit binary 248 11111000 187 10111011
Convert to decimal
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12. IPv4 address Prefix /24 Subnet mask: 192. 168. 21. 17 11000000
octet
network part
host part
Prefix /24 Subnet mask:
255.
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13. Find the network address
192.
168.
21. 17
In a network address, all the host bits are 0.
192.
168.
21.
The router needs to do this for every packet.
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14. Logical AND Do a logical AND at each position 192. 168. 21. 17
255.
192.
168.
21.
Do a logical AND at each position
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15. Find the broadcast address
192.
168.
21. 17
In a broadcast address, all the host bits are 1.
192.
168.
21.
255
The broadcast is the last address in the network.
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16. 3 types of address Every network has: Network address – the first one
Broadcast address – the last one
Host addresses – everything in between
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17. Classful addressing A B C 10. 17. 53. 60 172. 16. 38. 201 192. 168.
network part
host part B
172.
16.
38.
201
network part
host part C
192.
168.
21. 17
network part
host part
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18. Classful addressing Easy to work out but very wasteful.
Routers and hosts still assume class subnet masks by default
Class A /
Class B /
Class C /
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19. Classless addressing Any suitable prefix can be used
We (and devices) need to know what the prefix is.
More flexible, less wasteful.
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20. Classless addressing /16
/16 mask
Broadcast address
Hosts to
65534 host addresses
172.
16. 0.
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21. Classless addressing /24
/24 mask
Broadcast address
Hosts to
254 host addresses
172.
16. 0.
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22. Classless addressing /22
/22 mask
Broadcast address
Hosts to
1022 host addresses
172.
16. 0.
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23. Classless addressing /26
/22 mask
Broadcast address
Hosts to
62 host addresses
172.
16. 0.
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24. Classless addressing /28
/28 mask
Broadcast address
Hosts to
14 host addresses
172.
16. 0.
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25. Calculating addresses
A host has IP address /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?
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26. 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
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27. 192.168.1.70/24 Last octet binary Last octet decimal Full Host 70
Subnet mask
Network
Broadcast
255
First host 1
Last host
254
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28. Calculating addresses
A host has IP address /26
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?
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29. 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
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30. 192.168.1.70/26 Last octet binary Last octet decimal Full Host 70
Subnet mask
192
Network 64
Broadcast
127
First host 65
Last host
126
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31. Calculating addresses
A host has IP address /28
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?
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32. 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
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33. 192.168.1.70/28 Last octet binary Last octet decimal Full Host 70
Subnet mask
240
Network 64
Broadcast 79
First host 65
Last host 78
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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 locally
Multicast – a message addressed to a group of hosts. Uses an address starting
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35. Private IP addresses
Unrestricted use on private networks. Not routed across the Internet.
– ( /8)
– ( /20)
– ( /24)
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36. 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
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37. Special addresses
“all addresses” in default route. Hosts cannot be given addresses starting 0.
is loopback. Hosts cannot be given addresses starting 127.
and higher – reserved for experimental purposes.
local only
to for teaching
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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
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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
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40. Blocks of addresses Use Address range Summary Network address
/25
User hosts
Servers
/26
Peripherals
/27
Network devices
/27
Router
Broadcast
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41. Subnetting 192.168.1.0/24 Address 192.168.1.0 00000000 Subnet mask
Last octet binary
Address
Subnet mask
Borrow 1 bit from host part, give it to network part, /25
Addresses
Subnet mask
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42. Subnetting 192.168.1.0/24 Addresses
Borrow 2 bits from host part, give to network part, /26
Addresses
Subnet mask
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43. Subnetting 192.168.1.0/24 Addresses
Borrow 3 bits from host part, give to network part, /27
Addresses
Subnet mask
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44. Subnetting /24
Borrow 4 bits from host part, give to network part, /28
Subnet mask
And so on…
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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.
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46. Subnetting 192.168.1.0/24 Bits borrowed 1 2 3 4 5 6 No of networks 832 64
Prefix
/25
/26
/27
/28
/29
/30
Bit value/ network size
128
No of hosts
126 62 30 14
Subnet mask
192
224
240
248
252
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47. Address space Make a spreadsheet or table with numbers 0 to 255
Link to show table
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48. Subnet chart
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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.
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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 each router along the path replies. You get a list of addresses of all the routers.
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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
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52. The End