IP Classes - Revision history

Heth at 13:19, 5 September 2011

2011-09-05T13:19:34Z

Heth: /* Classes */

2010-01-25T06:12:29Z

‎Classes

Heth: /* Classes */

2010-01-25T06:11:46Z

‎Classes

Heth: /* Allocation */

2009-09-10T13:01:13Z

‎Allocation

Heth: /* Classes */

2009-02-24T11:09:51Z

‎Classes

Heth: /* Reserver address blocks */

2009-02-24T11:09:43Z

‎Reserver address blocks

Heth: /* Classes */

2009-02-24T11:09:05Z

‎Classes

Heth: /* Classes */

2009-02-23T11:09:28Z

‎Classes

Heth at 11:08, 23 February 2009

2009-02-23T11:08:50Z

Heth at 10:44, 23 February 2009

2009-02-23T10:44:08Z

@@ Line 1: / Line 1: @@
-==Classes==
+=Classes=
 To remain compatible with the existing IP address space and the IP packet structure, the definition of IP addresses was changed in 1981 in RFC 791 to allow unicast addresses with three different sizes of the ''network number'' field (and the associated ''rest'' field), as specified in the table below:
@@ Line 61: / Line 61: @@
 The method of comparing two IP addresses' physical networks did not change, however (see [[Subnetwork|subnet]]). For each address, the ''network number'' field size and its subsequent value were determined (the ''rest'' field was ignored). The network numbers were then compared.  If they matched, then the two addresses were on the same network.
-==Allocation==
+=Allocation=
 Originally, an IP address was divided into two parts:
 * Network ID: first octet
@@ Line 77: / Line 77: @@
 The actual assignment of an address is not arbitrary. The fundamental principle of [[routing]] is that the address of a device encodes information about the device's location within a network. This implies that an address assigned to one part of a network will not function in another part of the network. A hierarchical structure, created by CIDR and overseen by the [[Internet Assigned Numbers Authority]] (IANA) and its [[Regional Internet Registry|Regional Internet Registries]] (RIRs), manages the assignment of Internet addresses worldwide. Each RIR maintains a publicly-searchable [[WHOIS]] database that provides information about IP address assignments; information from these databases plays a central role in numerous tools that attempt to locate IP addresses geographically.
-== Reserver address blocks ==
+= Reservered address blocks =
 {| border=1
 |+ Reserved address blocks

@@ Line 10: / Line 10: @@
 ! Number <br>of Networks
 ! Hosts <br>per Network
-! IP<br>From to
+! IP<br>From IP -  to IP
 |-
 | Class A
@@ Line 34: / Line 34: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;2,097,152
 | &nbsp;&nbsp;&nbsp;&nbsp;254
-| &nbsp;&nbsp;&nbsp;&nbsp;192.0.0.0 223.255.255.0
+| &nbsp;&nbsp;&nbsp;&nbsp;192.0.0.0 - 223.255.255.0
 |-
 | Class D ([[IP Multicast]])

@@ Line 10: / Line 10: @@
 ! Number <br>of Networks
 ! Hosts <br>per Network
 |-
 | Class A
@@ Line 17: / Line 18: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;128
 | &nbsp;&nbsp;&nbsp;&nbsp;16,777,214
 |-
 | Class B
@@ Line 24: / Line 26: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;16,384
 | &nbsp;&nbsp;&nbsp;&nbsp;65,534
 |-
 | Class C
@@ Line 31: / Line 34: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;2,097,152
 | &nbsp;&nbsp;&nbsp;&nbsp;254
 |-
 | Class D ([[IP Multicast]])
@@ Line 38: / Line 42: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;not defined
 | &nbsp;&nbsp;&nbsp;&nbsp;not defined
 |-
 | Class E (reserved)
@@ Line 45: / Line 50: @@
 | &nbsp;&nbsp;&nbsp;&nbsp;not defined
 | &nbsp;&nbsp;&nbsp;&nbsp;not defined
 |}

@@ Line 64: / Line 64: @@
 To overcome this limit, different ''classes'' of network were defined, in a system which later became known as [[classful network]]ing.
 Five classes were created (A, B, C, D, and E), three of which (A, B, and C) had different lengths for the network field. The rest of an address was used to identify a host within a network, which meant that each network class had a different maximum number of hosts. Thus there were a few networks with each having many host addresses and numerous networks with each only having a few host addresses.
-Class D was for [[multicast]] addresses and Class E was reserved.
+Class D was for [[IP Multicast]] addresses and Class E was reserved.
 Around 1993, these classes were replaced with a [[Classless Inter-Domain Routing]] (CIDR) scheme, and the previous scheme was dubbed "classful", by contrast.
@@ Line 70: / Line 70: @@
 The actual assignment of an address is not arbitrary. The fundamental principle of [[routing]] is that the address of a device encodes information about the device's location within a network. This implies that an address assigned to one part of a network will not function in another part of the network. A hierarchical structure, created by CIDR and overseen by the [[Internet Assigned Numbers Authority]] (IANA) and its [[Regional Internet Registry|Regional Internet Registries]] (RIRs), manages the assignment of Internet addresses worldwide. Each RIR maintains a publicly-searchable [[WHOIS]] database that provides information about IP address assignments; information from these databases plays a central role in numerous tools that attempt to locate IP addresses geographically.
 == Reserver address blocks ==
 {| border=1

@@ Line 3: / Line 3: @@
 {| Border=1
-|- bgcolor=grey
+|- bgcolor=lightgrey
 ! Class
 ! Leading <br>Bits