- Originally (before the big
shortage on
IPv4 addresses),
the
IP addresses were divided into 5 classes:
- class A IP network address
- class B IP network address
- class C IP network address
- class D IP network address
- class E IP network address
- The IP address class
was organized by
the
prefix of the address:
- Class A
IP network address:
- Each
class A network can have upto
16,777,216 nodes:
- The Class A
networks are used to:
- Connect
the large number of
nodes
that forms
the Internet "backbone"
Wikipedia: click here
- Connect
the large number of
nodes
that forms
the Internet "backbone"
- Each
class A network can have upto
16,777,216 nodes:
- Class B
IP network address:
- Each
class B network can have upto
65,536 nodes:
- The Class B
networks are used to:
- Connect
the moderate number of
nodes (computers)
in a
company/organization
(Emory University used to have a class B network ID)
- Connect
the moderate number of
nodes (computers)
in a
company/organization
- Each
class B network can have upto
65,536 nodes:
- Class C IP address:
- Each
class C network can have upto
256 nodes:
- The Class C
networks are used to:
- Connect a computers of a small company/organization
- Each
class C network can have upto
256 nodes:
- Class D addresses:
Comments:
- Class D address
are used to identify a
communication group
- The communication group is
called: a
multicast group
- The class D addresses are called
Multicast addresses
- IP Multicasting
was introduced around
1992
by Steve Deering
- A multicast group is identified by a multicast address
- Class D address
are used to identify a
communication group
- Class E addresses:
- The class E addresses were
reserved for
future applications
- The class E addresses were
reserved for
future applications
- Why did we
design IPv6:
- US companies
discovered the
Internet around
1995
- Thanks to the killer application Mosaic, many companies want their website to advertise
This period was called the .COM boom - because the websites has the .com suffix...
- Class C networks were
too small for these
companies....
- Many requests were made
for Class B
addresses
during the
.COM boom.
- The Internet growth at that time hit a crisis level because the Internet was starting to run out Class B addressess !!!
- That's why a
new Internet protocol with
a large address was
standardized:
- There were 3 competing proposals
- The winner
was the "IPNG" (IP Next Generation)
protocol
- Since it was candidate 6, the new version of IP protocol is called IPv6 (version 6): click here
- There were 3 competing proposals
- US companies
discovered the
Internet around
1995
- Fact:
- The agency that
manages the
IP address assignments
detects the
alarming address drain around
1993
- They knew that a
new IP standard will
take a long time to
implement
- So while a
new standard we
being developed:
- A temporary fix was also developed
The temporary fix was so good, it slowed the deployment of IPv6...
- The agency that
manages the
IP address assignments
detects the
alarming address drain around
1993
- The temporary fix:
re-assigning IP addresses in
chunks of
arbitrary size
- The real of
address shortage problem:
- Actually:
- The Internet has plenty of unused IP address....
The Internet was not running out of IP addresses in general.
- More accurately:
- The Internet was running out of class B addresses...
Everyone that wanted to join the Internet, needed to have a Class B network
- In fact, Emory had a Class B network back in 1993....
- Actually:
- The cause of the
address shortage problem:
- Wastage !!!
Explanation:
- A class B network has
216 = 65536
IP-addresses
- Companies usually has
about 1000 computers
- Therefore:
- A company receives
65536 IP-addresses
when it is assigned a
class B network address
- But the company will
only use
1000 of these
IP-addresses !!!
Percentage wasted:
64536 ------- = 98.5% !!! 65536
So a lot of IP addresses were not usable due to the IP address structure !!!
- A company receives
65536 IP-addresses
when it is assigned a
class B network address
- A temporary fix:
- CIDR - classless Inter-Domain Routing
The temporary fix (CDIR) was so successful that in 2016, we are still running IPv4 in most of the US !!!
- Emory still run IPv4...