Lectures notes for 2010 - KTH

Classless addressing:
Subnetting IP networks
Often we want to “subnet” - i.e., divide the network up into multiple networks:
NetID SubnetID Host
Figure 28: IP addresses and subnetting
Although the Subnet field is shown as a field which is separate from the Host field,
it could actually be divided on a bit by bit basis; this is done by a Subnet Mask.
A common practice to avoid wasting large amounts of address space is to use
Classless Interdomain Routing (CIDR) also called “supernetting” {see §10.8 of
Steven’s Vol. 1 and RFCs 1518[20] and 1519[21]}.
Maguire Classless addressing: Subnetting IP networks 1: 91 of 104
maguire@kth.se 2010.03.21 Internetworking/Internetteknik