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

ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Objectives  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.

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

ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  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

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

ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public And Now for Something Completely Different!  Convert these numbers to Decimal

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

ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Discussion  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?

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

ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Classify and Define IPv4 Addresses  Determine the network, broadcast and host addresses for a given address and prefix combination

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

ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Out of Addresses?  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 /8, AT&T owns /8, Xerox owns /8, and HP owns /8 and /8, with Apple owning /8.

ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 16.8 Million Computers?  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?

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

ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Hijacking  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 ed 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 small- unincorporated 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.

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

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

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

ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Discussion  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?

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

ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public When to choose Static?  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.

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

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

ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Advantages and disadvantages of static versus DHCP addressing  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  Effective use of limited IP addresses

ITE PC v4.0 Chapter 1 26 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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 27 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Address Management  Describe addresses assigned by the ISP vs. assigned by the integrated router

ITE PC v4.0 Chapter 1 28 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Discussion  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

ITE PC v4.0 Chapter 1 29 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Discussion  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

ITE PC v4.0 Chapter 1 30 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public DHCP with DORA and you 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, " 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."

ITE PC v4.0 Chapter 1 31 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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 32 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Summary  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.

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