Chapter 7 - Classful IP Addressing

Class A Octect Range and Default Subnet Mask

1 -126, 255.0.0.0

Class B Octect Range and Default Subnet Mask

128-191, 255.255.0.0

Class C Octect Range and Default Subnet Mask

192-223, 255.255.255.0

Class A Address Range

1.0.0.0.1 -126.255.255.255

Class B Address Ranges

128.0.0.1-191.255.255.255

Class C Address Range

192.0.0.1-223.255.255.255

zero network 

0.0.0.0-0.255.255.255 (not used)

loopback network

127.0.0.1

network diagnostics 

127.0.0.0-127.255.255.255

two parts of IP address

• network part - identifies the LAN

• host part- identifies the computer in that LAN

subnet masks

determine which portion is the network and which is the host

octects of 255

network portion

octects of 0

host portion

Class A Subnet Mask (Binary) 255.0.0.0

11111111.00000000.00000000.00000000

Class B Subnet Mask (Binary)255.255.0.0

11111111.11111111.00000000.00000000

Class C Subnet Mask (Binary) 255.255.255.0

11111111.11111111.11111111.00000000

2 IP address that cant be used

network and broadcast address

Class A Number of Networks

126

Class A number of hosts per network

16,777,214

Class B number of networks

65,536

Class B Number of hosts 

65,534

Class C number of networks

16,777,216

Class C number of hosts per network

254

NAT

one to one mapping with each internal IP gets a public one

PAT

many-to-one mapping, mutliple itnteral IPs share one public IP address

Settings DHCP can issue

IP address, subnet mask, default gateway, DNS server

DHCP discover

client broadcast to locate DHCP server

DHCP offer

server offers an IP address

DHCP Request 

Client requests the offered address 

DHCP Acknowdgment 

Server confirms assignment 

Cisco DHCP

• router acts as DHCP server

• DHCP configured on router interface 

• functions on interface in same LAN as scope

IPv6 Addressing

provide unlimited IP addresses

IPv6 formatting

eight sections with 4 characters seperated by colons

iPv6 shortening rules

leading zeros in ech section con be ommitted

consecutive sections with only 0’s can use (::)

rule 2 can only be applies once per address 

unicast

packet delivered to one interface

multicast

packet delievered to multiple interfaces

any cast

packet goes to closest interface

global addresses

publicly routable, composed of MAC address, and starts with 2000

Link-Local Addresses 

unique only on local LAN/subnet with a prefix of FE80

unique local addresses 

only within an organization and orefix FC00/FD00

host portion

indentifies device uniquely

network portion

the network the device resides in

IP address

logical address that is used to uniquely indentify computing devices on the internet/networkIP

IP conflict

two computers that have the same IP address net

network ID

all bits are 0s

broadcast address

all bits are 1net

network ID is used 

to route packets to any computer in a LAN in their routing table

broadcast address is used

anytime a computer needs to send a packet to every host in its LAN

three ranges of private IP Addresses

A - 10.0.0.0 - 10.255.255.255

B- 172.16.0.0 - 172.31.255.255

C- 192.168.9.0 -192.68.255.255ip

ipconfig command

obtains information for troubleshooting every layer

ping command

troubleshoots internet and transport layers

ping 127.0.0.1

tests TCP/IP protocol and network adaptor card

ping local IP address

tests TCP/IP, network adaptor card, ip address, and subnet mask

ping default gateway

tests TCP/IP protocol, network adaptor card, ip address, subnet mask, and connects to outside LANspin

ping to computer in another LAN

fails = routing problem

succeeds = router working properly

socket

combination of the IP address and port number

arp command

stores mapping in memory in the arp chache

arp -s <MAC Address>

adds static entry to the arp cache 

arp -N<Interface IP address>

lists all arp entries for the interface specified a

arp - a or arp -g

displays all current ARP entires for all interfaces

tracer route and tracer command

used to determine the path to another network 

determine where along the path the connection is broken