The Upward Migration
Whether or not it has anything to say, the world wants to be connected. Royal Messengers, Pony Express riders, door-to-door mailmen, radio, and television all had their glory days, and now it’s the internet’s turn. At a very rapid rate, the internet’s population is increasing, and our available address base is shrinking.
127 = 01111111
0 = 00000000
0 = 00000000
1 = 00000001
It isn’t difficult to see why the octet quartering is necessary for human comprehension. These addresses are split into classes, which gives structure to the way they (the IP address ranges) are dispersed. Class A addresses are the largest group, providing for 16.7 million (224) contiguous addresses, identified by a first bit of “1”. The next largest class is Class B, allowing for 65.5 thousand (216) contiguous addresses, identified by the first two bits, “10”. The last (common) network is Class C, allowing for 256 (28) contiguous addresses, and is identified by the first three bits “110”.
Class A Class B Class C Class D
Addresses Avail. 16,777,216 65,563 256 Variable
Networks Avail. 128 16,384 2,097,152 268,435,456
Bit Identifier 0xxxxxxx 10xxxxxx 110xxxxx 1110xxxx
These IP addresses are 32 bits in length, and the bits are divided up as follows:
Decimal Denotation Version
4 IP Internet Protocol
5 ST ST Datagram
6 IP6 Internet Protocol version 6 [formerly SIP]
7 TP/IX Transport Protocol/Internet “Next”
8 PIP The “P” Internet Protocol
9 TUBA “TCP and UDP over Bigger Addresses”
Necessary to specify where the header ends and begins, since the Options bit area is of variable length.
Type Of Service:
Contains flags for Delay, Throughput, Reliability, and Cost, which make routing possible.
The length of the IP datagram.
These flags are for “Fragment” or “Don’t Fragment.” Allows or prevents breaking up of IP packets.
Controls the defragmentation the IP packet.
Time To Live:
The TTL flag accounts for a packet’s mortality. Each hop the packet experiences reduces the TTL flag by one. Upon reaching 0, a packet is dropped.
The two most common are UDP and TCP.
Source of the datagram
Intended recipient of the datagram.
Variable length items such as security, source route, record route, and timestamp.
Variable length- the content of the datagram.
The version 6 header looks like this:
The IP6 header is somewhat minimalist in comparison to the IP4 header, but the new features are these:
Permits administration of many packets from the same source based on “priority,” based on this scale:
0 Uncharacterized Traffic
1 Filler Traffic [news, banners, etc.]
2 Unattended data transfer [e-mail]
4 Unattended Bulk Transfer [FTP, NFS, CODA]
6 Interactive traffic [Telnet, Archie]
7 Internet Control Traffic [routing, SNMP]
8-15 Used for prioritization from a source that transmits without specifying Priorities. Currently no recommendations.
An experimental attempt at sending datagrams with preferred routes.
Specifies the length of the datagram itself, not including the header.
TTL with a more direct name.
128 bit specification of source.
128 bit specification of recipient.
This new addressing scheme allows for 3.4 X 1038 unique addresses, with no specified method of subnetting or supernetting. But with this many addresses, it shouldn’t be necessary.
W o r k s C i t e d
Graham, Buck. TCP/IP Addressing. Academic Press: New York (1997).
Halabi, Bassam. Internet Routing Architectures. New Riders Press: Indianapolis (1997).
Header representations from Graham’s TCP/IP Addressing.