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Cisco Discovery Home & Small Business Chapter 5 2 Teacher Notes  It is highly recommended that the instructor begin Chapter 5 with a series of activities teaching binary mathematics.  Can teach the use of scientific calculators but not permitted on certification exams.

Cisco Discovery Home & Small Business Chapter 5 3 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.

Cisco Discovery Home & Small Business Chapter 5 4 5.1.1 Purpose of the IP Address  A logical address unique to a particular device  IP Addresses assigned to host & end-user devices  A subnet mask identifies the network.  PACKET TRACER 5.1.1.2

Cisco Discovery Home & Small Business Chapter 5 5 5.1.2 IP Address Structure  32 Bits divided into four 8-bit sections called octets by periods  Addresses are assigned using decimal, not binary numbers  IP version 4 –Most common used –4 trillion (4,294,967,296) possible addresses (2 32 ) –Example - 192.168.1.5

Cisco Discovery Home & Small Business Chapter 5 6 Binary Game!  ACTIVITY 5.1.2.3

Cisco Discovery Home & Small Business Chapter 5 7 5.1.2 IP Address Structure (Binary Game)  32 Bits divided into 4 8-bit sections called octets by periods  Addresses are assigned using decimal, not binary numbers  IP version 4 –Most common used –4 trillion (4,294,967,296) possible addresses (2 32 )

Cisco Discovery Home & Small Business Chapter 5 8 5.1.3 Parts of an IP Address  IP Addressing is logical and heirarchical  Example Address 192.168.100.39 (Class C) –First section 192.168.100 is network portion –Second section 39 is host portion  Routers only need network address, not each host  Less info in tables, faster routing  Telephone system is also heirarchical, with country, area, and exchange codes.

Cisco Discovery Home & Small Business Chapter 5 10 5.1.4 How IP Addresses and Subnet Masks Interact  Number of Hosts by Bits –If there are 8 host bits, there are 2 8 hosts possible, or 256 (0-255) –16 bits - 2 16, or 65,536 –24 bits - 2 24, or 16,777,216  IP address that have all zeros in the host portion are network or subnetwork addresses, not available for hosts assignment  IP addresses with all 1s in the host portion are broadcast addresses, also not assigned

Cisco Discovery Home & Small Business Chapter 5 11 5.1.4 How IP Addresses and Subnet Masks Interact AND Logic  1 and 1 = 1  1 and 0 = 0  0 and 1 = 0  0 and 0 = 0

Cisco Discovery Home & Small Business Chapter 5 12 5.2.1 IP Address Classes and Default Subnet Masks  5 Classes of IP address Default subnet masks Network Size/ Purpose  Large  Medium  Small  Multicast  Experim ental

Cisco Discovery Home & Small Business Chapter 5 13 5.2.2 Private and Public IP Addresses  Public addresses are unique out on the Internet  Risk of using up all unique addresses  Introducing private addressing…

Cisco Discovery Home & Small Business Chapter 5 14 5.2.2 Private and Public IP Addresses  RFC 1918 - Private Addressing –Can be used within private network without going on Internet –Class A - Very Large - Over 16 million –Class B - Medium, about 65,000 –Class C - Small, only 256 addresses, or 254 hosts –Unique class, 127.0.0.0 used for loopback addresses

Cisco Discovery Home & Small Business Chapter 5 15 5.2.2 Private and Public IP Addresses

Cisco Discovery Home & Small Business Chapter 5 17 5.2.3 Unicast, Broadcast, and Multicast Messages  The IP packet has been encapsulated by the Framing information.

Cisco Discovery Home & Small Business Chapter 5 18 5.2.3 Unicast, Broadcast, and Multicast Messages

Cisco Discovery Home & Small Business Chapter 5 19 5.2.3 Unicast, Broadcast, and Multicast Messages

Cisco Discovery Home & Small Business Chapter 5 20 5.3.1 Static and Dynamic Address Assignment  Methods of assigning an IP Address –Static Configured by host administrator Used for servers, printers, and other devices shared by users Time consuming List must be maintained Can introduce errors –Dynamic Good where assignments change often DHCP (Dynamic Host Control Protocol) used Assigns other default information –Subnet mask –Default gateway –DNS server, etc. Leased for period of time and returned to pool when not in use

Cisco Discovery Home & Small Business Chapter 5 21 5.3.2 DHCP Servers  At the ISP (cable modem)  At the ISP (internal to ISP)  ISR in the home  Dedicated DHCP server in a business

Cisco Discovery Home & Small Business Chapter 5 22 5.3.3 Configuring DHCP  Newly configured hosts have no IP address, subnet mask, or gateway  Needs to get this from a DHCP Server  DHCP Process to get settings information: –DHCP DISCOVER Packet Broadcast –IP: 255.255.255.255 –MAC: FF:FF:FF:FF:FF:FF –DHCP server Replies with OFFER containing suggested IP address –Host sends REQUEST asking to use IP Address –Server replies with ACKNOWLEDGEMENT

Cisco Discovery Home & Small Business Chapter 5 23 DHCP Configuration on ISR

Cisco Discovery Home & Small Business Chapter 5 24 DHCP Configuration on ISR

Cisco Discovery Home & Small Business Chapter 5 25 Animation 5.4.2.1 – Address Assignment

Cisco Discovery Home & Small Business Chapter 5 26 DHCP Configuration  SOHO Networks usually use an ISR for DHCP  The basic DHCP Settings: –Default network address for gateway on an ISR is normally a private Class C (192.168.1.1, 192.168.100.1) –A pool of addresses –Lease time for address –Maximum number of hosts Can you exceed 20?  Every host must have this Gateway address configured –Either statically or dynamically –What does this mean? Describe process –PACKET TRACER – 5.3.3.3

Cisco Discovery Home & Small Business Chapter 5 27 5.4.1 Network Boundaries and Gateways  Routers for local networks provide gateway for communication to other networks  Each Interface on router is a separate network connection  IP Addresses on interfaces identify networks connected  ISP Side of the router –ISPs use DHCP to give addresses to SOHO routers connecting to their network –ISRs act as a DHCP client when connecting to ISP

Cisco Discovery Home & Small Business Chapter 5 28 Internet Connection Methods  Direct Connection –Single computer connected through a modem –ISP is assigned directly through modem to a single host  Connection through ISR – with Modem (WAN Device) –Many computers connected to ISR –ISR connected to ISP using connection through modem –ISP assigns address to ISR interface connected to modem –Hosts assigned addresses from ISR  Connection through Gateway Device – no Modem –Many computers connected to ISR –ISR connected to ISP with integrated modem port –ISP assigns address to ISR interface connected to modem –Hosts assigned addresses from ISR

Cisco Discovery Home & Small Business Chapter 5 29 Internet Connection Methods

Cisco Discovery Home & Small Business Chapter 5 30 5.4.3 Network Address Translation  ISP provides public address for ISR to use externally  ISR provides private addresses used on internal network  NAT (Network Address Translation) is used to bridge the gap and match the public and private addresses.  Packets sent to the Internet have their IP addresses stripped away and another, external address assigned.  Reverse process is applied with incoming traffic.  Animation 5.4.3.1

Cisco Discovery Home & Small Business Chapter 5 31 Using NAT with a Home or Small Business Network

Cisco Discovery Home & Small Business Chapter 5 32 Using NAT with a Home or Small Business Network

Cisco Discovery Home & Small Business Chapter 5 33 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.

Cisco Discovery Home & Small Business Chapter 5 34 Teacher Notes  URL for Subnetting guide - http://www.cisco.com/en/US/tech/tk365/technologies_ tech_note09186a00800a67f5.shtml http://www.cisco.com/en/US/tech/tk365/technologies_ tech_note09186a00800a67f5.shtml  Students need to practice –Binary to Decimal Conversion –Decimal to Binary Conversion –Address Class Identification –Network and Host Identification –Default Subnet Masks  Subnet Workbook Guide

Cisco Discovery Home & Small Business Chapter 5 35