Information about Internet Protocol
Internet protocol may refer to:
The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork.
IP is a network layer protocol in the Internet protocol suite and is encapsulated in a data link layer protocol (e.g., Ethernet). As a lower layer protocol, IP provides the service of communicable unique global addressing amongst computers.
To address any of these reliability issues, an upper layer protocol must handle it. For example, to ensure in-order delivery the upper layer may have to cache data until it can be passed up in order.
If the upper layer protocol does not self-police its own size by first looking at the Layer 2 Maximum Transmission Unit (MTU) size, and sends the IP layer too much data, IP is forced to fragment the original datagram into smaller fragments for transmission. IP does provide re-ordering of any fragments that arrive out of order by using the fragmentation flags and offset[1]. Transmission Control Protocol (TCP) is a good example of a protocol that will adjust its segment size to be smaller than the MTU. User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) are examples of protocols that disregard MTU size thereby forcing IP to fragment oversized datagrams.[2]
The primary reason for the lack of reliability is to reduce the complexity of routers. While this does give routers carte blanche to do as they please with packets, anything less than best effort yields a poorer experience for the user. So, even though no guarantees are made, the better the effort made by the network, the better the experience for the user. Most protocols are built around the idea that error checking is best done at each end of the communication line, see End-to-end principle.
IPv6 is the proposed successor to IPv4 whose most prominent change is the addressing. IPv4 uses 32-bit addresses (~4 billion addresses) while IPv6 uses 128-bit addresses (~3.4×1038 addresses). Although adoption of IPv6 has been slow, as of 2008, all United States government systems must support IPv6 (if only at the backbone level). [3]
Version numbers 0 through 3 were development versions of IPv4 used between 1977 and 1979. Version number 5 was used by the Internet Stream Protocol (IST), an experimental stream protocol. Version numbers 6 through 9 were assigned to experimental protocols designed to replace IPv4: SIPP (known nowadays as IPv6), TP/IX, PIP, and TUBA. Of these, only IPv6 is still in use.
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- The Internet Protocol, a data-oriented protocol used for communicating data across a packet-switched internetwork
- The Internet protocol suite, a set of communications protocols that implement the protocol stack on which the Internet runs
The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork.
IP is a network layer protocol in the Internet protocol suite and is encapsulated in a data link layer protocol (e.g., Ethernet). As a lower layer protocol, IP provides the service of communicable unique global addressing amongst computers.
Packetization
Data from an upper layer protocol is encapsulated inside one or more packets/datagrams (the terms are basically synonymous in IP). No circuit setup is needed before a host tries to send packets to a host it has previously not communicated with (this is the point of a packet-switched network), thus IP (Internet protocol) is a connectionless protocol. This is quite unlike Public Switched Telephone Networks that require the setup of a circuit before a phone call may go through (a connection-oriented protocol).Services provided by IP
Because of the abstraction provided by encapsulation, IP can be used over a heterogeneous network (i.e., a network connecting two computers can be any mix of Ethernet, ATM, FDDI, Wi-Fi, token ring, etc.) and it makes no difference to the upper layer protocols. Each data link layer can (and does) have its own method of addressing (or possibly the complete lack of it), with a corresponding need to resolve IP addresses to data link addresses. This address resolution is handled by the Address Resolution Protocol (ARP).)
Encapsulation of user data in a UDP datagram inside an IP packet.
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An example IP header as captured by ethereal.
Reliability
IP provides an unreliable service (i.e., best effort delivery). This means that the network makes no guarantees about the packet and none, some, or all of the following may apply:- data corruption
- out of order (packet A may be sent before packet B, but B can arrive before A)
- duplicate arrival
- lost or dropped/discarded
To address any of these reliability issues, an upper layer protocol must handle it. For example, to ensure in-order delivery the upper layer may have to cache data until it can be passed up in order.
If the upper layer protocol does not self-police its own size by first looking at the Layer 2 Maximum Transmission Unit (MTU) size, and sends the IP layer too much data, IP is forced to fragment the original datagram into smaller fragments for transmission. IP does provide re-ordering of any fragments that arrive out of order by using the fragmentation flags and offset[1]. Transmission Control Protocol (TCP) is a good example of a protocol that will adjust its segment size to be smaller than the MTU. User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) are examples of protocols that disregard MTU size thereby forcing IP to fragment oversized datagrams.[2]
The primary reason for the lack of reliability is to reduce the complexity of routers. While this does give routers carte blanche to do as they please with packets, anything less than best effort yields a poorer experience for the user. So, even though no guarantees are made, the better the effort made by the network, the better the experience for the user. Most protocols are built around the idea that error checking is best done at each end of the communication line, see End-to-end principle.
IP addressing and routing
Perhaps the most complex aspects of IP are IP addressing and routing. Addressing refers to how end hosts become assigned IP addresses and how subnetworks of IP host addresses are divided and grouped together. IP routing is performed by all hosts, but most importantly by internetwork routers, which typically use either interior gateway protocols (IGPs) or external gateway protocols (EGPs) to help make IP datagram forwarding decisions across IP connected networks.Version history
IP is the common element found in today's public Internet. The current and most popular network layer protocol in use today is IPv4; this version of the protocol is assigned version 4. IPv4 RFC-791 was adopted by the United States Department of Defense as MIL-STD-1777.IPv6 is the proposed successor to IPv4 whose most prominent change is the addressing. IPv4 uses 32-bit addresses (~4 billion addresses) while IPv6 uses 128-bit addresses (~3.4×1038 addresses). Although adoption of IPv6 has been slow, as of 2008, all United States government systems must support IPv6 (if only at the backbone level). [3]
Version numbers 0 through 3 were development versions of IPv4 used between 1977 and 1979. Version number 5 was used by the Internet Stream Protocol (IST), an experimental stream protocol. Version numbers 6 through 9 were assigned to experimental protocols designed to replace IPv4: SIPP (known nowadays as IPv6), TP/IX, PIP, and TUBA. Of these, only IPv6 is still in use.
See also
- Main lists: List of basic internet topics and List of Internet topics
- Connectionless protocol
- IANA
- Internet protocol suite
- IPv4
- IPv5
- IPv6
- IP address
- TCP and UDP port numbers
- Transmission Control Protocol
- ip - the ip structure for the C programming language
- Internet
- Country IP database
References
External links
- Internet Protocol at the Open Directory Project
- RFC 791
The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It has also been referred to as the TCP/IP protocol suite, which is named after two of the most important protocols in it:
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protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication.
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Packet switching is a communications paradigm in which packets (discrete blocks of data) are routed between nodes over data links shared with other traffic. In each network node, packets are queued or buffered, resulting in variable delay.
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Internetworking involves connecting two or more distinct computer networks or network segments together to form an internetwork (often shortened to internet), using devices which operate at layer 3 (Network layer) of the OSI Basic Reference Model (such as routers or
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network layer is the third layer out of seven in OSI model and the third layer out of five in TCP/IP model. In the TCP/IP reference model it is called the Internet layer.
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The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It has also been referred to as the TCP/IP protocol suite, which is named after two of the most important protocols in it:
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encapsulation is to include data from an upper layer protocol into a lower layer protocol. This is a method of abstraction for networking by allowing different layers to add features/functionality.
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data link layer is layer two of the seven-layer OSI model as well as of the five-layer TCP/IP reference model. It responds to service requests from the network layer and issues service requests to the physical layer.
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Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media
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In computer networking, the lower layer protocol (LLP) refers to the more specific protocol when performing encapsulation. It contrasts with upper layer protocol which refers to the more abstract protocol.
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In computer networking, the upper layer protocol (ULP) refers to the more abstract protocol when performing encapsulation. It contrasts with lower layer protocol which refers to the more specific protocol.
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A telecommunication circuit is defined as follows:
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- The complete path between two terminals over which one-way or two-way communications may be provided. See communications protocol.
- An electronic path between two or more points, capable of providing a number of channels.
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Packet switching is a communications paradigm in which packets (discrete blocks of data) are routed between nodes over data links shared with other traffic. In each network node, packets are queued or buffered, resulting in variable delay.
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In telecommunications, connectionless describes communication between two network end points in which a message can be sent from one end point to another without prior arrangement.
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The public switched telephone network (PSTN) is the network of the world's public circuit-switched telephone networks, in much the same way that the Internet is the network of the world's public IP-based packet-switched networks.
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A heterogeneous network is a network connecting computers and other devices with different operating systems and/or protocols. For example, local area networks (LANs) that connect Microsoft Windows and Linux based personal computers with Apple Macintosh computers are heterogeneous.
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Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media
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Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells.
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Fiber distributed data interface (FDDI) provides a standard for data transmission in a local area network that can extend in range up to 200 kilometers (124 miles). Although FDDI protocol is a token ring network, it does not use the IEEE 802.
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Wi-Fi (pronounced wye-fye, IPA: /ˈwaɪfaɪ/), also unofficially known as Wireless Fidelity
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Token ring local area network (LAN) technology was conceived in the late 1960s by Olof Söderblom, then working for IBM [1] ). US Patents were awarded in 1981 and Token-Ring was developed and promoted by IBM in the early 1980s and standardized as IEEE 802.
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In computer networking, the upper layer protocol (ULP) refers to the more abstract protocol when performing encapsulation. It contrasts with lower layer protocol which refers to the more specific protocol.
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In computer networking, the Address Resolution Protocol (ARP) is the standard method for finding a host's hardware address when only its network layer address is known.
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Best effort delivery describes a network service in which the network does not provide any guarantees that data is delivered or that a user is given a guaranteed quality of service level or a certain priority.
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checksum is a form of redundancy check, a simple way to protect the integrity of data by detecting errors in data that are sent through space (telecommunications) or time (storage).
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The Internet Control Message Protocol (ICMP) is one of the core protocols of the Internet protocol suite. It is chiefly used by networked computers' operating systems to send error messages—indicating, for instance, that a requested service is not available or that a
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In computer networking, the upper layer protocol (ULP) refers to the more abstract protocol when performing encapsulation. It contrasts with lower layer protocol which refers to the more specific protocol.
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In computer networking, the upper layer protocol (ULP) refers to the more abstract protocol when performing encapsulation. It contrasts with lower layer protocol which refers to the more specific protocol.
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The Internet Protocol allows IP fragmentation so that datagrams can be fragmented into pieces small enough to pass over a link with a smaller MTU than the original datagram size.
RFC 791 describes the procedure for IP fragmentation, transmission and reassembly of datagrams.
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RFC 791 describes the procedure for IP fragmentation, transmission and reassembly of datagrams.
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