CTI Technician TrainingCTI Technician Training

Internet ProtocolInternet Protocol

Part 1Part 1

IP BasicsIP Basics

IP addresses are allocated by one of four non-IP addresses are allocated by one of four non-profit Regional Internet Registries.profit Regional Internet Registries.ARIN, the American Registry for Internet ARIN, the American Registry for Internet Numbers, serves North America.Numbers, serves North America.Registries usually allocate IP addresses to large Registries usually allocate IP addresses to large organizations, such as telephone companies or organizations, such as telephone companies or ISP’s. Then those organizations distribute IP ISP’s. Then those organizations distribute IP addresses to users.addresses to users.CTI’s network is now large enough to request CTI’s network is now large enough to request IP’s directly from ARIN.IP’s directly from ARIN.ARIN’s website is www.arin.net.ARIN’s website is www.arin.net.

Dotted Decimal and Binary FormDotted Decimal and Binary Form

208.7.90.198208.7.90.198==

11010000.00000111.01011010.1100011011010000.00000111.01011010.11000110

Four octets containing 8 bits each = 32 bitsFour octets containing 8 bits each = 32 bits

Binary Bit ValuesBinary Bit Values2277 2266 2255 2244 2233 2222 2211 2200

128128 6464 3232 1616 88 44 22 11

11 11 00 11 00 00 00 00

128 + 64 + 0 + 16 + 0 + 0 + 0 + 0 = 208128 + 64 + 0 + 16 + 0 + 0 + 0 + 0 = 208

Leftmost bit is called the Most Significant BitLeftmost bit is called the Most Significant Bit

Rightmost bit is called the Least Significant BitRightmost bit is called the Least Significant Bit

Add bit values together to convert to decimalAdd bit values together to convert to decimal

Fill in bit values needed to convert to binary.Fill in bit values needed to convert to binary.

Classfull IP AddressingClassfull IP Addressing

When IP addressing was first developed, When IP addressing was first developed, classes were created to allocate addresses to classes were created to allocate addresses to organizations.organizations.

Classes A, B, and C were introduced.Classes A, B, and C were introduced.

The class of network you received depended on The class of network you received depended on the current size and projected growth of your the current size and projected growth of your organization.organization.

Class A NetworksClass A Networks

First octet ranges 1-126.First octet ranges 1-126.

First octet bits 0xxxxxxx.First octet bits 0xxxxxxx.

126 networks.126 networks.

16,777,214 hosts per network.16,777,214 hosts per network.

Allocated to very large organizations.Allocated to very large organizations.

Class B NetworksClass B Networks

First octet ranges 128 - 191.First octet ranges 128 - 191.

First octet bits 10xxxxxx.First octet bits 10xxxxxx.

16,384 networks.16,384 networks.

65,534 hosts per network.65,534 hosts per network.

Allocated to medium sized organizations.Allocated to medium sized organizations.

Class C NetworksClass C Networks

First octet ranges 192 - 223.First octet ranges 192 - 223.

First octet bits 110xxxxx.First octet bits 110xxxxx.

2,097,152 networks.2,097,152 networks.

254 hosts per network.254 hosts per network.

Allocated to small organizations.Allocated to small organizations.

Other ClassesOther Classes

Class D (Multicast)Class D (Multicast)– First octet ranges 224 – 239.First octet ranges 224 – 239.– First octet bits 1110xxxx.First octet bits 1110xxxx.– Used exclusively for multicasting.Used exclusively for multicasting.

Class E (Experimental)Class E (Experimental)– First octet ranges 240 – 254.First octet ranges 240 – 254.– First octet bits 1111xxxx.First octet bits 1111xxxx.– Used for research.Used for research.

Reserved or Private ClassesReserved or Private Classes

10.0.0.0 – 10.255.255.255 10.0.0.0 – 10.255.255.255

127.0.0.0 – 127.255.255.255 (loopback)127.0.0.0 – 127.255.255.255 (loopback)

169.254.0.0 – 169.254.255.255 (apipa)169.254.0.0 – 169.254.255.255 (apipa)

172.16.0.0 – 172.31.255.255172.16.0.0 – 172.31.255.255

192.168.0.0 – 192.168.255.255192.168.0.0 – 192.168.255.255

Private or reserved addresses cannot be Private or reserved addresses cannot be routed on the Internet.routed on the Internet.

Network Address TranslationNetwork Address Translation

A NAT device acts as a gateway to the A NAT device acts as a gateway to the Internet for computers with private Internet for computers with private addresses.addresses.

Helps to alleviate worsening IPv4 limits.Helps to alleviate worsening IPv4 limits.

Subnet MasksSubnet Masks

What is a subnet mask?What is a subnet mask?– A subnet mask specifies what portion of the A subnet mask specifies what portion of the

address defines the network and what portion address defines the network and what portion defines the host.defines the host.

– Like an IP address, a subnet mask is a 32 bit Like an IP address, a subnet mask is a 32 bit number.number.

– Can be displayed in dotted decimal form, Can be displayed in dotted decimal form, such as 255.255.254.0.such as 255.255.254.0.

– Can be displayed as a CIDR block, such as Can be displayed as a CIDR block, such as 65.160.198.0 /23.65.160.198.0 /23.

Subnet MasksSubnet Masks

Given two IP addresses, a subnet mask Given two IP addresses, a subnet mask can be used to determine whether the can be used to determine whether the addresses are on the same network or addresses are on the same network or subnet.subnet.

What happens when the two IP addresses What happens when the two IP addresses are not on the same network?are not on the same network?– A router is used to link different subnets.A router is used to link different subnets.

How Does Easy Subnetting Work?How Does Easy Subnetting Work?

Subnetting is easier to understand when working in binary.Subnetting is easier to understand when working in binary.

NetworkNetwork HostHost

208208 77 9090 198198

1101000011010000 0000011100000111 0101101001011010 1100011011000110

1111111111111111 1111111111111111 1111111111111111 0000000000000000

255255 255255 255255 00Masked bits

Not-So-Easy Subnetting…Not-So-Easy Subnetting…

What happens when masked bits do not fall What happens when masked bits do not fall evenly on octets?evenly on octets?– You get a subnet mask like these:You get a subnet mask like these:255.255.240.0 – 11111111.11111111.11110000.00000000255.255.240.0 – 11111111.11111111.11110000.00000000255.192.0.0 – 11111111.11000000.00000000.00000000255.192.0.0 – 11111111.11000000.00000000.00000000255.224.0.0 – 11111111.11100000.00000000.00000000255.224.0.0 – 11111111.11100000.00000000.00000000255.255.255.128 – 11111111.11111111.11111111.10000000255.255.255.128 – 11111111.11111111.11111111.10000000

Notice a pattern?Notice a pattern?Masked bits must be contiguous.Masked bits must be contiguous.

In other words, once you stop masking,In other words, once you stop masking,no other bits can be masked.no other bits can be masked.

Valid Subnet MasksValid Subnet Masks

Since masked bits must be contiguous, there are Since masked bits must be contiguous, there are only 8 valid decimal values for any one octet.only 8 valid decimal values for any one octet.

128128 6464 3232 1616 88 44 22 11

128128 192192 224224 240240 248248 252252 254254 255255

11 11 11 11 11 00 00 00

128 + 64 + 32 + 16 + 8 + 0 + 0 + 0 = 248

Finding the network id and broadcast address.Finding the network id and broadcast address.

Each network has two special addresses:Each network has two special addresses:– The network id is used by Internet routers to route traffic to the network. This is The network id is used by Internet routers to route traffic to the network. This is

always the always the firstfirst address in the network. Host portion is all 0’s address in the network. Host portion is all 0’s– The broadcast address is used to broadcast traffic to the entire network. This The broadcast address is used to broadcast traffic to the entire network. This

is always the is always the lastlast address in the network. Host portion is all 1’s. address in the network. Host portion is all 1’s.

208208 77 9090 198198

1101000011010000 0000011100000111 0101101001011010 1100011011000110

1111111111111111 1111111111111111 1111000011110000 0000000000000000

255255 255255 240240 00

11010000.00000111.01010000.00000000 or 208.7.80.0 is the network id.

11010000.00000111.01011111.11111111 or 208.7.95.255 is the broadcast address.

Bitwise ANDing Bitwise ANDing

Humans can easily draw a line between the Humans can easily draw a line between the network bits and host bits.network bits and host bits.

Hosts and routers use Boolean math to Hosts and routers use Boolean math to determine the network id and the host id by the determine the network id and the host id by the use of ANDing. use of ANDing.

Bit 1Bit 1 11 00 11 00Bit 2Bit 2 11 11 00 00

ResultResult 11 00 00 00

Four possibilities of ANDing:

Using Windows Calculator, you can AND 208.007.090.198 with 255.255.240.000 to get 208.007.080.000

Questions or Comments?Questions or Comments?

Adam Vocks - MCP, MCSEAdam Vocks - MCP, MCSEVice-PresidentVice-PresidentComputer Techniques, Inc.Computer Techniques, Inc.Adam@ctitech.comAdam@ctitech.com