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Friday 19 June 2015

Internet Protocol

Internet Protocol

Internet Protocol (IP)

ü  The Internet Protocol (IP) - is the principal communications protocol used for relaying datagrams (also known as network packets) across an internetwork using the Internet Protocol Suite.

-responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet.
-is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering datagrams from the source host to the destination host solely based on the addresses.
-for this purpose, IP defines datagram structures that encapsulate the data to be delivered.
-it also defines addressing methods that are used to label the datagram source and destination.

Historically, IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974, the other being the connection-oriented Transmission Control Protocol (TCP). The Internet Protocol Suite is therefore often referred to as TCP/IP.


The Internet Protocol is responsible for addressing hosts and routing datagrams (packets) from a source host to the
destination host across one or more IP networks.

The Internet Protocol

-is one of the elements that define the Internet. The dominant internetworking protocol in the Internet Layer in use today is IPv4; the number 4 is the protocol version number carried in every IP datagram. IPv4 is described in RFC 791 (1981).


1.       Internet Protocol Version 4 (IPv4)
- first major version of IP, is the dominant protocol of
the internet.
            -is the fourth revision in the development of the Internet Protocol (IP) and the first version of the protocol to be widely deployed.
            - together with IPv6, it is at the core of standards-based internetworking methods of the Internet. As of 2012 IPv4 is still the most widely deployed Internet Layer protocol.
            -is described in IETF publication RFC 791 (September 1981), replacing an earlier definition (RFC 760, January 1980).
            - IPv4 is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). It operates on a best effort delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the Transmission Control Protocol (TCP).
            - Its most prominent modification from version 4 is the addressing system. IPv4 uses 32-bit addresses (c. 4 billion, or 4.3×109, addresses) while IPv6 uses 128-bitaddresses (c. 340 undecillion, or 3.4×1038 addresses).
- IPv4 uses 32-bit addresses, allowing for only 4,294,967,296 unique addresses worldwide.
2.      Internet Protocol Version 6(IPv6)

- Its successor of IPv4
- which is increasing in use.
-) is a revision of the Internet Protocol (IP) developed by the Internet Engineering Task Force (IETF).
-is intended to succeed IPv4, which is the dominant communications protocol for most Internet traffic as of 2012.
- use 128 bits for the address, was developed in 1995. IPv6 was standardized as RFC 2460 in 1998, and its deployment has been on-going since the mid-2000s.

- is the new version of the Internet Protocol. The addresses used by the current version of the Internet Protocol, IPv4, are nearly all used.
            - was developed to deal with the long-anticipated problem of IPv4 running out of addresses. IPv6 implements a new addressing system that allows for far more addresses to be assigned than with IPv4.
- Each device on the Internet, such as a computer or mobile telephone, must be assigned an IP address in order to communicate with other devices. With the ever-increasing number of new devices being connected to the Internet, there is a need for more addresses than IPv4 can accommodate. IPv6 uses 128-bit addresses, allowing for 2128, or approximately 3.4×1038 addresses.
IPv6 addresses, as commonly displayed to users, consist of eight groups of four hexadecimal digits separated by colons, for example2001:0db8:85a3:0042:0000:8a2e:0370:7334.

The deployment of IPv6 is accelerating, with a World IPv6 Launch having taken place on 6 June 2012, in which major internet service providers, especially in countries that had been lagging in IPv6 adoption, deployed IPv6 addresses to portions of their users. Data from Arbor Networks showed a peak of 0.2% of Internet traffic on IPv6 during the launch

v  IP addresses are binary numbers, but they are usually stored in text files and displayed in human-readable notations, such as (for IPv4), and 2001:db8:0:1234:0:567:8:1 (for IPv6).
v  The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities.

IPv6 Summary

  • 128-bit address space
  • revised header format
  • new options
  • allowance for extension
  • support for special handling of packet flows
  • increased security measures
  • IPv6 uses hexadecimal colon notation with abbreviation
  • methods
  • IPv6 has 3 types of addresses: unicast, any cast, and
  • multicast
  • IPv4, ICMPv4, ARP, RARP, and IGMP replaced with IPv6
  • and ICMPv6
  • IPv4 to IPv6 transition strategies are dual stack,
  • tunnelling, and header translation 

IP Addressing and Routing 

- addressing refers to how end hosts are assigned IP addresses and how subnetworks of IP host addresses are divided and grouped.
-IP routing is performed by all hosts, but most importantly by routers, which typically use either interior gateway protocols (IGPs) or external gateway protocols (EGPs) to decide how to move datagrams among networks.
-IP routing is also common in local networks. For example, Ethernet switches sold today support IP multicast. These switches use IP addresses and Internet Group Management Protocol for control of the multicast routing but use MAC addresses for the actual routing.

IP versions 0 to 3 were development versions of IPv4 and were used between 1977 and 1979.
Version 5 was used by the Internet Stream Protocol, an experimental streaming protocol.
Version numbers 6 through 9 were proposed for various protocol models designed to replace IPv4: SIPP (Simple Internet Protocol Plus, known now as IPv6), TP/IX (RFC 1475), PIP (RFC 1621) and TUBA (TCP and UDP with Bigger Addresses, RFC 1347).
Other protocol proposals named IPv9 and IPv8 briefly surfaced, but have no support.
On April 1, 1994, the IETF published an April Fool's Day joke about IPv9.

ü  Transmission Control Protocol (TCP)

-is an 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) disregard MTU size, thereby forcing IP to fragment oversized datagrams.
Transmission Control Protocol (TCP)

The TCP provides reliable transmission of data in an IP environment. TCP corresponds to the transport layer (Layer 4) of the OSI reference model. Among the services TCP provides are stream data transfer, reliability, efficient flow control, full-duplex operation, and multiplexing.

With stream data transfer, TCP delivers an unstructured stream of bytes identified by sequence numbers. This service benefits applications because they do not have to chop data into blocks before handing it off to TCP. Instead, TCP groups bytes into segments and passes them to IP for delivery.

TCP offers reliability by providing connection-oriented, end-to-end reliable packet delivery through an internetwork. It does this by sequencing bytes with a forwarding acknowledgment number that indicates to the destination the next byte the source expects to receive. Bytes not acknowledged within a specified time period are retransmitted. The reliability mechanism of TCP allows devices to deal with lost, delayed, duplicate, or misread packets. A time-out mechanism allows devices to
detect lost packets and request retransmission.
TCP offers efficient flow control, which means that, when sending acknowledgments back to the
source, the receiving TCP process indicates the highest sequence number it can receive without
overflowing its internal buffers.
Full-duplex operation means that TCP processes can both send and receive at the same time.
Finally, TCP’s multiplexing means that numerous simultaneous upper-layer conversations can be
multiplexed over a single connection.

User Datagram Protocol (UDP)

- is one of the core members of the Internet protocol suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol (IP) network without requiring prior communications to set up special transmission channels or data paths. The protocol was designed by David P. Reed in 1980 and formally defined in RFC 768.

UDP uses a simple transmission model without implicit handshaking dialogues for providing reliability, ordering, or data integrity. Thus, UDP provides an unreliable service and datagrams may arrive out of order, appear duplicated, or go missing without notice. UDP assumes that error checking and correction is either not necessary or performed in the application, avoiding the overhead of such processing at the network interface level. Time-sensitive applications often use UDP because dropping packets is preferable to waiting for delayed packets, which may not be an option in a real-time system. If error correction facilities are needed at the network interface level, an application may use the Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP) which are designed for this purpose.

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