Networking for Home and Small Businesses – Chapter 5
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
1

ITE PC v4.0
Chapter 1
 Describe the purpose of an IP address and Subnet
Mask and how they are used on the Internet.
 Describe the types of IP Addresses available.
 Describe the methods of obtaining an IP Address.
 Describe the use of NAT on a home or small business network using an Integrated Router.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
2

Purpose of an IP Address and Subnet Mask
 Review the purpose of the IP address
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
3

ITE PC v4.0
Chapter 1
 IP Addresses enable routing on the Internet and most modern LANs
 IP Addresses are hierarchical and made up of 32 bits
 Subnets allow routing devices to route packets across networks
 Known as IPv4, there are over 4 billion possible IP addresses using this 32bit addressing scheme
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
4

Purpose of an IP Address and Subnet Mask
 Describe the structure of an IP address
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
5

ITE PC v4.0
Chapter 1
 Convert these numbers to Decimal
1. 00011011
2. 10101010
3. 01101111
4. 11000000
5. 01010101
6. 00100000
7. 11101101
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
6

 Practice converting decimal to 8-bit binary
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
7

Purpose of an IP Address and Subnet Mask
 Identify and describe the parts of the IP address and their purpose
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
8

ITE PC v4.0
Chapter 1
 What would be the advantage(s) to being able to divide physical networks into logical networks?"
 Why does dividing a physical network into a logical network provide these benefits?
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
9

Purpose of an IP Address and Subnet Mask
 Describe a subnet mask and its purpose
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
10

 Determine the network, broadcast and host addresses for a given address and prefix combination
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
11

 Describe the classes of IP address and the default subnet mask
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
12

ITE PC v4.0
Chapter 1
 In Chapter 4 we talked about the very real problem of the diminishing number of IP addresses while more and more devices are being introduced every day that require IP addresses! It is amazing to look at how many addresses are owned by General Electric. They own the entire 3.0.0/8 subnet while the United States Army owns 6.0.0/8, IBM owns 9.0.0.0/8, AT&T owns
12.0.0.0/8, Xerox owns 13.0.0.0/8, and HP owns
15.0.0.0/8 and 16.0.0.0/8, with Apple owning
17.0.0.0/8.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
13

ITE PC v4.0
Chapter 1
 Since each Class A subnet has 16.8 million addresses, you can see that all together, these companies own quite a few addresses!
 Do you think that all these addresses are being used?
 Why do you think these companies bought so many addresses?
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
14

 Describe private and public addressing and when each is used
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
15

ITE PC v4.0
Chapter 1
 The people who keep the Internet running are coming to terms with address space hijacking, an old scam that has suddenly turned nasty. Earlier this year an expanse of Internet address space belonging to the County of Los Angeles was put to some uses that had little to do with effective municipal governance. Some county addresses inexplicably began generating suspicious scanning activity that tripped intrusion detection systems around the net.
Then there was the spam - suddenly offers of low-interest mortgages, bargain ink jet cartridges, and similar items were being emailed to residents throughout. Los Angeles County. It turns out the official records of the address block had been doctored, and
Los Angeles County no longer owned the space - at least as far as the rest of the world was concerned. All 65,534 addresses now belonged to Emil Kacperski, the 20-something owner of a smallunincorporated hosting company in Northern California . These
"unused" addresses in the County of Los Angeles Class B block of addresses were hijacked. The hijacking nearly escaped detection, had it not been for a spam complaint that started an investigation.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
16

 Differentiate between Unicast, Broadcast, Multicast
Addresses
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
17

 Differentiate between Unicast, Broadcast, Multicast
Addresses
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
18

 Differentiate between Unicast, Broadcast, Multicast
Addresses
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
19

ITE PC v4.0
Chapter 1
 Imagine you are one of two network support technicians for a static-IP addressed 300-host network.
 What would be involved in changing any or all of the
TCP/IP settings in a static IP environment?
 At a minimum, what network information would have to be configured?
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
20

Methods of Obtaining an IP Address
 Review the methods of assigning an IP Address
Static Assignment
Dynamic Assignment
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
21

ITE PC v4.0
Chapter 1
 Devices that need to be shared by multiple clients on a network should have static addresses, as should those devices to which access might need to be controlled.
 Examples (printers, servers, switches, routers) of devices requiring static IP addresses,
 Explain the reason for selection of a particular device.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
22

Methods of Obtaining an IP Address
 Describe where the DHCP services are located
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
23

Methods of Obtaining an IP Address
 Configure and verify DHCP range on the GUI-based home-integrated router
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
24

 Staffing
 Entry errors
 Configuration of machines
 Centralization of IP addresses
 Management of IP addresses
 Changing of TCP/IP settings including subnet mask, IP address range, gateway, and DNS server (depending upon the length of the lease)
 Mobile device network connectivity
ITE PC v4.0
 Effective use of limited IP addresses
© 2007 Cisco Systems, Inc. All rights reserved.
Chapter 1 Cisco Public
25

Using DHCP with a Home or Small Business
Network
 Describe the boundaries of a network as it relates to address space
 Discuss Gateways
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
26

Address Management
 Describe addresses assigned by the ISP vs. assigned by the integrated router
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
27

ITE PC v4.0
Chapter 1
 Why can you turn an ordinary computer host into a
DHCP server?
 Where you would place the DHCP server within a network?
 Would you place the server within the local network with the clients or external to the client network?
 What are the pros and cons of having a DHCP server on each and every network segment versus having some network segments receive IP address assignments over a router
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
28

ITE PC v4.0
Chapter 1
 What happens if the DHCP server goes down or becomes unavailable?"
 What will be the effect of placing DHCP servers with clients in terms of subnetting?
Need an IP
Address??
Follow DORA
•Discover
•Offer
•Request
•Acknowledge
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
29

ITE PC v4.0
Chapter 1
1.
You request an address via a broadcast message
DHCP Discover a. Make sure the message is correct for destination IP address and MAC address. You say,
"255.255.255.255 MAC address FF-FF-FF-FF-FF-FF" b. Other clients "hear" the message, but it is ignored by all but the server who "perks up"
2.
The server sends a DHCP Offer suggesting an IP address for the client (from a pool provided to the server). The server say, "Would you like address..."
3.
The host then sends a DHCP Request asking to use the address. You say, "May I use that address please?"
4.
Then the server responds with a DHCP
Acknowledgement saying "That would be just fine."
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
30

Using NAT with a Home or Small Business
Network
 Describe the use of NAT on a home or small business network using an integrated router
ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
31

ITE PC v4.0
Chapter 1
 IP addresses are unique 32-bit addresses grouped into four 8-bit bytes called octets.
 IP addresses use a two-part hierarchical structure of network bits and host bits.
 IP addresses and subnet masks are used by routers to determine the network location of hosts.
 IP addresses are grouped into classes according to the number of bits used for designating the network, and further divided into public and private ranges.
 Private IP addresses must be translated to public IP addresses in order to move through the Internet.
 IP addresses can be assigned statically or dynamically.
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
32

ITE PC v4.0
Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved.
Cisco Public
33