02-18-2011
Hi
An IPv4 address contains 4 octets i.e. 32 bits. ip addresses are divided into 4 classes depending upon how many bits in 32 bits represent the network address and how many bits represent the host address.
for instance the class A ip address has the first 8 bits represent the network address and rest 24 bits represent the host address.
A network mask is the one which helps you finding which part in 32 bits represents the network address. Say for class A the network mask is 255.0.0.0
So in general a class A ip address can be represented as 1.2.3.4 255.0.0.0
There is another concept called as sub-netting which makes use of some bits in the host part for network address. Sub-netting allows you to create multiple logical networks inside classes of networks.
for example we can create an IP subnet for class A by using 3 bits of 24 host bits for network address. In this case the first 11 bits of 32 represent the network address and the reset 21 bits represent the host address.
In such cases the class A address can be represented as 1.2.3.4 255.224.0.0
The above representation is called as address/mask representation.. There is another representation know as CIDR (Classless inter-domain routing) which represents the ip address irrespective of class, but represents the number of bits used for network address.
In the CIDR representation the ip address in the above example is represented as 1.2.3.4/11 since 11 bits are used as mask.
so, in the representation of ip address 193.32.156.0/24 and 169.183.0.0/16, 24 and 16 represent the mask bits...so the above two addresses are class c and class b respectively.
Thanks,
Chaitanya.
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IP-TOKEN(8) Linux IP-TOKEN(8)
NAME
ip-token - tokenized interface identifier support
SYNOPSIS
ip token { COMMAND | help }
ip token set TOKEN dev DEV
ip token del dev DEV
ip token get [ dev DEV ]
ip token [ list ]
DESCRIPTION
IPv6 tokenized interface identifier support is used for assigning well-known host-part addresses to nodes whilst still obtaining a global
network prefix from Router advertisements. The primary target for tokenized identifiers are server platforms where addresses are usually
manually configured, rather than using DHCPv6 or SLAAC. By using tokenized identifiers, hosts can still determine their network prefix by
use of SLAAC, but more readily be automatically renumbered should their network prefix change [1]. Tokenized IPv6 Identifiers are described
in the draft [1]: <draft-chown-6man-tokenised-ipv6-identifiers-02>.
ip token set - set an interface token
set the interface token to the kernel.
TOKEN the interface identifier token address.
dev DEV
the networking interface.
ip token del - delete an interface token
delete the interface token from the kernel.
dev DEV
the networking interface.
ip token get - get the interface token from the kernel
show a tokenized interface identifier of a particular networking device. Arguments: coincide with the arguments of ip token set but the
TOKEN must be left out.
ip token list - list all interface tokens
list all tokenized interface identifiers for the networking interfaces from the kernel.
SEE ALSO
ip(8)
AUTHOR
Manpage by Daniel Borkmann
iproute2 28 Mar 2013 IP-TOKEN(8)