- IPv4 address:
- IPv4 address = a
32 bit binary number
that is made up and used to
identify a
node in the Internet
uniquely
- There are 232 = 4,294,967,296 different IPv4 addresses
- IPv4 address = a
32 bit binary number
that is made up and used to
identify a
node in the Internet
uniquely
- IPv6 address:
- IPv6 address = a 128 bit binary number
- Dotted decimal notation:
- An IPv4 addres is
often written
as
4 groups of
decimal numbers:
xx.xx.xx.xx where each xx is a decimal numberExample:
170.140.150.1 represents: 170 = 10101010 (binary representation of 170) 140 = 10001100 150 = 10010110 1 = 00000001 170.140.150.1 = 10101010 10001100 10010110 00000001
- An IPv4 addres is
often written
as
4 groups of
decimal numbers:
- IPv6 address notation:
- An IPv6 addres is
often written
as
8 groups of
4 hexadecimal digits,
separated by ':':
xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx where each x is a hexadecimal digitThe initial zero's are suppressed and 2 or more 0000 groups may be compressed by ::
Example:
2001:0db8:0a0b:12f0:0000:0000:0000:0001 is writted as: 2001:db8:a0b:12f0:0:0:0:1 and comprssed to: 2001:db8:a0b:12f0::1
- An IPv6 addres is
often written
as
8 groups of
4 hexadecimal digits,
separated by ':':
- Assigning IP addresses to
nodes:
- In theory
- You could assign IP addresses in an arbitrary manner (= without any constraint) to nodes
(As long as 2 different nodes have different IP addresses)
- In theory
- Problem:
- Since:
- A node in the Internet must know the location of every Internet nodes
The routing table can potentially have:
- 232 = 4,294,967,296 entries !!!
That's a lot of memory (especially in 1980 !!!)
- Since:
- In order to reduce the
size of the
routing table:
- Nodes (= computers and routers) on the same physical network must have the same prefix for IP address
Example:
- Experiment:
host lab1a: lab1a.mathcs.emory.edu has address 170.140.151.110 lab1b.mathcs.emory.edu has address 170.140.151.111 lab5h.mathcs.emory.edu has address 170.140.151.149 compute.mathcs.emory.edu has address 170.140.150.8Notice that:
- Every node on
the MathCS department network has the
prefix:
10101010 10001100 10010110 xxxxxxxx (max 255 nodes) 170 140 150
- Every node on
the MathCS department network has the
prefix:
- Fact:
- IP addresses
are structured
(Not arbitrary)
- IP addresses
are structured
- The format of
an IP address:
where:
- Network ID part:
- identifies a network "domain"
- Host ID part:
- identifies one specific node (host) inside a network domain
- Network ID part:
- Consequences of
the (imposed)
structure of
IP addresses:
- IP routing is
based on
network IDs
Routing table contains:
Network ID | Output port ----------------+------------------ Netw Addr 1 | port 1 Netw Addr 2 | port 2 .... | ....(This will reduce the routing table size considerably)
- All IP hosts
on the same IP network
must have:
- the same Network ID !!!
This consequence will make mobile IP hosts a tougher problem than it ought to be....
- IP routing is
based on
network IDs