1. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.1 Computer Networks and Internets with Internet Applications, 4e By Douglas E. Comer Lecture PowerPoints By Lami Kaya, LKaya@ieee.org

2. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.2 Chapter 22 The Future IP (IPv6)

3. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.3 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 IPv6 Features 22.6 IPv6 Datagram Format 22.7 IPv6 Base Header Format 22.8 How IPv6 Handles Multiple Headers 22.9 Fragmentation, Reassembly, And Path MTU 22.10 The Purpose Of Multiple Headers 22.11 IPv6 Addressing 22.12 IPv6 Colon Hexadecimal Notation

4. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.4 22.1 Introduction This chapter concentrates on the future of the Internet Protocol begins by assessing the strengths and limitations of the IPv4 considers an entirely new version of IP that the IETF is developing to replace IPv4 explains features of the new version shows how they overcome some of the limitations in IPv4

5. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.5 22.2 The Success Of IP The demonstration of scalability is evident because IPv4 includes millions of users IPv4 has also accommodated changes in HW –Several generations of HW –Faster LANs –Different frame sizes

6. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.6 22.3 The Motivation For Change Why change then? Motivations: –IPv4 has limited address space –New applications require complex addressing/routing capabilities –Group collaborations, load sharing

7. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.7 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 IPv4, most researchers expected the next official version of IPv5 –However, version number 5 had been assigned to an experimental protocol known as ST The new version 6, protocol known as IPv6

8. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.8 22.5 IPv6 Features IPv6 retains many features of IPv4, but IPv6 changes all the details New features in IPv6: Address Size –Instead of 32 bits, each IPv6 address contains 128 bits. Header Format –Header is completely different Extension Headers –IPv6 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

9. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.9 22.6 IPv6 Datagram Format As Figure 22.1 illustrates, –an IPv6 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

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11. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.11 22.7 IPv6 Base Header Format Although it is twice as large as an IPv4 header –the IPv6 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 IPv4's datagram length field NEXT HEADER –specify the type of information that follows the current header

12. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.12

13. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.13

14. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.14 22.8 How IPv6 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

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16. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.16 22.9 Fragmentation, Reassembly, And Path MTU (1) Fragmentation in IPv6 differs from fragmentation in IPv4 In IPv4, router fragmentations when a datagram too large for the NW In IPv6, a sending host is responsible for fragmentation –Hosts choose a datagram size that will not require fragmentation –Routers will not fragment the datagram

17. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.17 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

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19. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.19 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 IPv6, 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

20. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.20 22.11 IPv6 Addressing IPv6 addressing differs from IPv4 IPv6 includes addresses with a multi-level hierarchy –ISP  Company  Site  so on IPv6 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

21. © 2007 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.21 22.12 IPv6 Colon Hexadecimal Notation Writing such 128-bit numbers can be unwieldy –Consider a 128-bit number written in dotted decimal notation: 105.220.136.100.255.255.255.255.0.0.18.128.140.10.255.255 IPv6 propose using a compact syntactic form known as colon hexadecimal notation Above number is written in colon hex 69DC : 8864 : FFFF : FFFF : 0 : 1280 : 8C0A : FFFF Zero compression replaces sequences of zeroes with two colons –Ex: FF0C : 0 : 0 : 0 : 0 : 0 : 0 : B1  FF0C : : B1