1. Ip addressing & subnetting
Chapter 5b

2. objectives Upon completion of this chapter, you should be able to:
Configure IP addresses
Identify & select valid IP addresses for networks
Configure a DHCP server
Configure a host to use DHCP for configuration
Troubleshoot & resolve IP addresses configuration and communication issues
Configure DNS addresses
Configure an IPv6 address

3. 5.1.3
Classful subnetting

4. Parts of the Network
Network
Hosts
Subnetwork

5. Subnetting- Split Up the IP address
Borrow bits from host portion to make new networks
Ask yourself…
How many networks do you need?
How many hosts per network are there?
Instead of wasting a whole IP address range, you can split up an address & customize it for your network.
In the picture: You have 4 networks & E1:4 hosts; E0 on A: 3 hosts; S0 to S1: 2 hosts; B’s E0: 3 hosts
Think about expansion too.

6. Remember 2 addresses you can’t use: Network & Broadcast
Some rules first…
You MUST borrow at least 2 bits or leave at least 2 bits
Class C has 1 octet to borrow from
Class B has 2 octets to borrow from
Class A has 3 octets to borrow from
Remember the powers of 2
22= 4
23= 8
24= 16
25= 32
26= 64
Remember 2 addresses you can’t use: Network & Broadcast

7. 199.72.101.0 Ask how many networks do we need? 4
2 to the what power will get you 4? 2^2 but if you subtract 2, you’ll only have 2, so use 2^3=8
What class address? C…..use only 1 octet
Mark off bits borrowed (looking for networks)
Create new subnet mask
Powers of 2 chart for borrowed (networks) and left over (hosts/net)
Create ranges
Remove 1st & last ranges

8.
Total Range #3
Useable Range #2
Network ID
/27
Broadcast Address
/27
( )
( )
( )
( )
( )
( )
Make sure to explain network and broadcast for each sub network. SHOW all zeros in the host bits!

9. Assign Addresses
Note that each router port is a sub-network! When two routers connect to each other, both ports MUST be in the same network.

10. Router…Action!
A packet with a destination IP of goes to a router
It ANDs to come up with the NETWORK #

11. How to Work Backwards 221.17.125.46 /28 What class address?
C: Only deal with the last octet!
How many bits borrowed? 4
24= 16 networks
How many bits left over?
24= 16 hosts per sub-network

12. Work Backwards Based on the IP address & SM, identify…
The network address
The broadcast address
How many bits were borrowed
How many bits were left over
Is the address valid

13. What’s Wrong?
PC1 has an address of /28. PC2 has an address of /28. Both are connected to a switch but they cannot communicate. The switch is working normally as are the PC’s NICs and Ethernet cables. Are the hosts on the same network or separate?
Different subnets.

14. Questions What’s the broadcast address for 201.78.90.0 /24?
Default SM, no subnetting
Sam’s Beef Hut uses network & to create subnets. How many useable hosts can be created per network? 14

15. Questions Which class gives you the most hosts/network?
Which class give you the most networks? C
Public IP addresses must be __________.

16. 5.1.5
Classless subnetting

17. Classless Subnetting
Allows you to use part of the address for the network portion
Called partial subnetting or VLSM
CIDR allows this
Helps reduce wasted addresses
You can subnet for each unequal network
Your address is /26
Net A needs 37 hosts
Net B needs 15 hosts
Net C needs 100 hosts

18. CIDR Block for Router
Reduce the amount of routing table entries, use router summarization
Use the common bits to make ONE routing table address per port.
This is also called supernetting. It reduces the amount of routing table entries (they use the same supernet; which is called router summarization).
In the picture, supernetting will reduce entries in router A’s routing table.

19. Test on addressing & subnetting

20. Ip addressing & subnetting
Chapter 5b
4-5 days including test