IP4

From bildr

Jump to: navigation, search

IPv4

IPv4 formatted addresses contains 32 bits of information, limiting the address pace to 4294967296 (<math>2^32</math>) possibilities. Certain addressed are reserved for private networks and multicase addresses.

The typical format is view in dot-decimal notation, where four numbers ranging from 0 to 255 are separated by periods (e.g. 192.168.0.1). Each parts represents 8 bits of the address and is referred to as an "octet". IP addresses may be represented in hexadecimal, octal, or binary forms as well, though they are less common and usually still separated into octets. Likewise, IP Addresses typically are followed by a subnetwork designation, defined as a "/" at the end of the address, followed by the subnetwork number.

Reserved addresses listed in RFC 5735.

Reserved_IPv4_addresses
CIDR IP Range Number of Unique Addresses Locality Purpose
0.0.0.0/8 0.0.0.0–0.255.255.255 16777216 Subnet Used for broadcast messages to the current ("this") network as specified by 1700, page 4.
10.0.0.0/8 10.0.0.0–10.255.255.255 16777216 Subnet Used for local communications within a private network as specified by 1918.
127.0.0.0/8 127.0.0.0–127.255.255.255 16777216 Local Used for loopback addresses to the local host.
169.254.0.0/16 169.254.0.0–169.254.255.255 65536 Subnet Used for autoconfiguration between two hosts on a single link when no IP address is otherwise specified, such as would have normally been retrieved from a DHCP server.
172.16.0.0/12 172.16.0.0–172.31.255.255 1048576 Subnet Used for local communications within a private network as specified by 1918
192.0.2.0/24 192.0.2.0–192.0.2.255 256 Subnet Assigned as "TEST-NET" for use solely in documentation and example source code and should not be used publicly.
192.88.99.0/24 192.88.99.0–192.88.99.255 256 Global Used by anycast relays as specified by 3068.
192.168.0.0/16 192.168.0.0–192.168.255.255 65536 Subnet Used for local communications within a private network as specified by 1918.
198.18.0.0/15 198.18.0.0–198.19.255.255 131072 Private network Used for testing of inter-network communications between two separate subnets as specified in 2544.
198.51.100.0/24 198.51.100.0–198.51.100.255 256 Subnet Assigned as "TEST-NET-2" for use solely in documentation and example source code and should not be used publicly.
203.0.113.0/24 203.0.113.0–203.0.113.255 256 Subnet Assigned as "TEST-NET-3" for use solely in documentation and example source code and should not be used publicly.
224.0.0.0/4 224.0.0.0–239.255.255.255 268435456 Global Reserved for multicast assignments as specified in 3171
240.0.0.0/4 240.0.0.0–255.255.255.255 268435456 Global 255.255.255.255 is reserved for the "limited broadcast" destination address. All others in this block are reserved for future allocation by the IANA.


IPv4 Addresses contain a header section and a data section.

The header packet consist of 13 fields, 12 required fields. The fields have the most significant byte first (big endian), and usually the most significant bits are first (MSD 0 bit numbering).

IPv4 Header bits
bit offset 0–3 4–7 8–13 14-15 16–18 19–31
0 Version Header Length Differentiated Services Code Point Explicit Congestion Notification Total Length
32 Identification Flags Fragment Offset
64 Time to Live Protocol Header Checksum
96 Source IP Address
128 Destination IP Address
160 Options ( if Header Length > 5 )
160

or

192+
 

Data

 


The contents of the data field are defined in the header, and can be a variety of different transport layer protocols. For example, TCP has a value of "6", which UDP has a value of "17".

Related Pages

This page is an Article on bildr. Articles are pages that define or explain a concept, method, or generic item.

NOTE: All information contained within this article is pure opinion. Although this article is intended to help people, it may contain faulty or misleading information. This article is not to be considered professional opinion or advice, and is in no way a replacement for reading all safety/instructional documentation. Always remember to protect yourself when handling/using hazardous materials, as well as test new techniques before using them on projects/work intended to be handed in or used.

bildr and its contributers take NO responsibility for the information contained within.