Chapter 11: Perspectives on IPv4 Subnetting

subnet

allow a single Class A, B, or C network to be used instead of multiple networks, and still allow for a large number of groups of IP addresses, as is required for efficient IP routing

different

Addresses in ________ subnets are separated by at least one router.

same

Addresses in the ________ subnet are not separated by a router

VLANs

Point-to-point serial links

Ethernet WAN

what are some instances where subnets would need to be created?

subnet mask

A 32-bit number that numerically describes the format of an IP address, by representing the combined network and subnet bits in the address with mask bit values of 1, and representing the host bits in the address with mask bit values of 0.

subnet mask

defines the size of that subnet

2^h - 2

subnet useable IP equation

to account for the subnet number and the broadcast address

why is the subnet host formula 2^h - 2? Why subtract 2?

VLSM

The capability to specify a different subnet mask for the same Class A, B, or C network number on different subnets. Can help optimize available address space.

classful network

An IPv4 Class A, B, or C network; called this because these networks are defined by the class rules for IPv4 addressing.

private IP network

Any of the IPv4 Class A, B, or C networks as defined by RFC 1918, intended for use inside a company but not used as public IP networks

public IP network

Any IPv4 Class A, B, or C network assigned for use by one organization only, so that the addresses in the network are unique across the Internet, allowing packets to be sent through the public Internet using the addresses.

NAT

allows multiple companies to use the exact same private IP network, using the same IP addresses as other companies while still connecting to the Internet

10.0.0.0 (1 network)

class A private network

172.16.0.0 - 172.31.0.0 (16 networks)

class B private network

192.168.0.0 - 192.168.255.0 (256 networks)

class C private network

Avoiding using another organization's public address range for private networks

Delaying IPv4 address exhaustion

Reducing Internet routers' routing table size

Three ways private networks have improved IPV4's implementation worldwide?

network part

The portion of an IPv4 address that is either 1, 2, or 3 octets/bytes long, based on whether the address is in a Class A, B, or C network.

host part

A term used to describe a part of an IPv4 address that is used to uniquely identify a host inside a subnet. Identified by the bits of value 0 in the subnet mask

subnet part

In a subnetted IPv4 address, interpreted with classful addressing rules, one of three parts of the structure of an IP address, with the _________ _______ uniquely identifying different subnets of a classful IP network.

number of needed subnets

2^S can be used to calculate what?

subnet number

this number identifies the subnet, it is the numerically smallest number in the subnet.

subnet broadcast

this is the last (numerically highest) number in the subnet