Computer Networks and Internets with Internet Applications 4

Computer Networks and Internets with Internet Applications, 4 e By Douglas E. Comer Lecture Power. Points By Lami Kaya, LKaya@ieee. org © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

Chapter 22 The Future IP (IPv 6) © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

Topics Covered • • • 22. 1 Introduction 22. 2 The Success Of IP 22. 3 The Motivation For Change 22. 4 A Name And A Version Number 22. 5 IPv 6 Features 22. 6 IPv 6 Datagram Format 22. 7 IPv 6 Base Header Format 22. 8 How IPv 6 Handles Multiple Headers 22. 9 Fragmentation, Reassembly, And Path MTU 22. 10 The Purpose Of Multiple Headers 22. 11 IPv 6 Addressing 22. 12 IPv 6 Colon Hexadecimal Notation © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 1 Introduction This chapter • concentrates on the future of the Internet Protocol • begins by assessing the strengths and limitations of the IPv 4 • considers an entirely new version of IP that the IETF is developing to replace IPv 4 • explains features of the new version • shows how they overcome some of the limitations in IPv 4 © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 2 The Success Of IP • The demonstration of scalability is evident because IPv 4 includes millions of users • IPv 4 has also accommodated changes in HW – Several generations of HW – Faster LANs – Different frame sizes © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 3 The Motivation For Change • Why change then? Motivations: – IPv 4 has limited address space – New applications require complex addressing/routing capabilities – Group collaborations, load sharing © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 4 A Name And A Version Number • Distinguish a protocol from all other proposals? – Use an official version number in the header • Because the current IPv 4 , most researchers expected the next official version of IPv 5 – However, version number 5 had been assigned to an experimental protocol known as ST • The new version 6, protocol known as IPv 6 © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 5 IPv 6 Features IPv 6 retains many features of IPv 4, but IPv 6 changes all the details New features in IPv 6: • Address Size – Instead of 32 bits, each IPv 6 address contains 128 bits. • Header Format – Header is completely different • Extension Headers – IPv 6 encodes information into separate headers • Support For multimedia – Allows a sender/receiver to establish a high-quality path • Extensible Protocol – Not specify all possible protocol features, open to new extensions © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 6 IPv 6 Datagram Format • As Figure 22. 1 illustrates, – an IPv 6 datagram begins with a base header – followed by zero or more extension headers – followed by data • The figure are not drawn to scale: – some extension headers are larger than the base header • while others can be smaller – in many datagrams, the size of the data area is much larger than the size of the headers © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

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22. 7 IPv 6 Base Header Format • Although it is twice as large as an IPv 4 header – the IPv 6 base header contains less information, as shown in Fig. 22. 2 • TRAFFIC CLASS – specifies the traffic class which is used to choose a route – specifies general characteristics that the datagram needs • FLOW LABEL – for use with new applications that require performance guarantees – associate a datagram with a particular path – it has been partitioned into TRAFFIC CLASS • PAYLOAD LENGTH – corresponds to IPv 4's datagram length field • NEXT HEADER – specify the type of information that follows the current header © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

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22. 8 How IPv 6 Handles Multiple Headers • NEXT HEADER field is used to determine what follows: – If the value corresponds to a type used for data • the receiver passes the datagram to a module that handles the data – If the value corresponds to another header • IP SW parses the header and interprets its contents • Where a particular header ends and the next item begins? – Some header types have a fixed size and some are variable – The length of the options header in field HEADER LEN © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

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22. 9 Fragmentation, Reassembly, And Path MTU (1) • Fragmentation in IPv 6 differs from fragmentation in IPv 4 • In IPv 4, router fragmentations when a datagram too large for the NW • In IPv 6, a sending host is responsible for fragmentation – Hosts choose a datagram size that will not require fragmentation – Routers will not fragment the datagram © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 9 Fragmentation, Reassembly, And Path MTU (2) • How to choose a datagram size? – Hosts must learn the MTU of each NW along the path • The minimum MTU along is known as the path MTU • Learning the path MTU is known as “path MTU discovery” • Path MTU discovery is an iterative procedure – A host sends a sequence of various-size datagrams to the destination to see if they arrive without error – Once a datagram is small enough to pass through without fragmentation, the host chooses a size equal to the path MTU © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

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22. 10 The Purpose Of Multiple Headers • There are two reasons: economy and extensibility • Economy – Partitioning the datagram functionality into separate headers is economical because it saves space – Smaller datagrams also take less time to transmit – Reducing datagram size also reduces the bandwidth • Extensibility – useful for adding a new feature to a protocol – In IPv 6, existing protocol headers can remain unchanged. • NEXT HEADER type is defined as well as a new header format • Main advantage of placing new functionality in a new header is ability to experiment new protocols © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 11 IPv 6 Addressing • IPv 6 addressing differs from IPv 4 • IPv 6 includes addresses with a multi-level hierarchy – ISP Company Site so on • IPv 6 defines a set of special addresses, each one being of three basic types: – Unicast, a single computer – Multicast, a set of computers, possibly at many locations – Anycast (cluster), a set of hosts sharing a common prefix © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.

22. 12 IPv 6 Colon Hexadecimal Notation • Writing such 128 -bit numbers can be unwieldy – Consider a 128 -bit number written in dotted decimal notation: 105. 220. 136. 100. 255. 0. 0. 18. 128. 140. 10. 255 • IPv 6 propose using a compact syntactic form known as colon hexadecimal notation • Above number is written in colon hex 69 DC : 8864 : FFFF : 0 : 1280 : 8 C 0 A : FFFF • Zero compression replaces sequences of zeroes with two colons – Ex: FF 0 C : 0 : 0 : 0 : B 1 FF 0 C : : B 1 © 2007 Pearson Education Inc. , Upper Saddle River, NJ. All rights reserved.