1. © MMII JW RyderCS 428 Computer Networking1 The Future of TCP/IP (IPv6)  Chapter 33  Evolution of TCP/IP intertwined with evolution of the global Internet  Internet is largest installed internet  Funding comes from organizations that are Internet users  Most researchers use Internet daily  Chapter purpose is to consider ongoing evolution of TCP/IP

2. © MMII JW RyderCS 428 Computer Networking2 Why Change?  New computer and communication technologies  New technologies = new possibilities and needs  New applications  New ways to use Internet means new protocols needed  Increases in size and load  Massive growth means old ways strained

3. © MMII JW RyderCS 428 Computer Networking3 Motivation for Changing IPv4  New countries with differing administrative policies  IPv4 same for about 20 years  Since IPv4 designed  Enhanced processor performance  Memory size increased  Network bandwidth for Internet backbone increased  New LAN technologies  Number of hosts on Internet risen to over 56 million

4. © MMII JW RyderCS 428 Computer Networking4 Road to New Version of IP  Several suggested designs  Make IP more sophisticated at expense of increased complexity and processing overhead  Use a modification of OSI CLNS protocol  Retain most of ideas in IP but make simple extensions to accommodate larger addresses  Simple IP – (SIP)  Still include new ideas from other suggested protocols

5. © MMII JW RyderCS 428 Computer Networking5 Features of IPv6  Despite many conceptual similarities IPv6 changes most protocol details  Completely revises datagram format  Replace IPv4 variable length fields with a series of fixed format headers  Still supports connectionless delivery  Allows sender to choose datagram size but requires sender to specify maximum hops

6. © MMII JW RyderCS 428 Computer Networking6 Features of IPv6  Includes facilities for fragmentation and source routing  Main changes introduced are 1. Larger Addresses: IPv6 quadruples the size from 32 bits to 128 bits 2. Extended Address Hierarchy: Creates ability to have additional address levels on an internet  IPv4 Addresses – 2 levels, Network and Host  IPv6 Addresses – Can define a hierarchy of ISPs as well as hierarchy within a site

7. © MMII JW RyderCS 428 Computer Networking7 Features of IPv6 3. Flexible Header Format: Datagram format entirely different  Defines a fixed size (40 octets) header with optional extended headers 4. Improved Options:  Has same options as IPv4 plus some new ones 5. Provision for Protocol Extension:  Move away from protocol that fully specifies all details to one that permits additional features

8. © MMII JW RyderCS 428 Computer Networking8 Features of IPv6 6. Support for Autoconfiguration and Renumbering:  Allows computers on an isolated network to assign themselves addresses and begin communicating without depending on a router or manual configuration  Facility to permit a manager to renumber networks dynamically

9. © MMII JW RyderCS 428 Computer Networking9 Features of IPv6 7. Support for Resource Allocation:  Two facilities for pre-allocation of network resources  a Flow abstraction  a Differentiated Services specification

10. © MMII JW RyderCS 428 Computer Networking10 IPv6 Address Space  How big is 2 128 ?  So large that everyone on earth will have enough addresses to have their own internets with as many addresses as the current Internet has  So large that there would be 10 24 internet addresses per each square meter on earth  So large that the address space is greater than 3.4 * 10 38  If addresses are assigned at the rate of 1,000,000 every microsecond (1/1,000,000 th of a second), it would take more than 10 20 years to assign all possible addresses

11. © MMII JW RyderCS 428 Computer Networking11 IPv6 Colon Hexadecimal Notation  128 bit number expressed as dotted decimal  104.230.140.100.255.255.255.255.0.0.17.128.150.10.255.255 becomes  68E6:8C64:FFFF:FFFF:0:1180:96A:FFFF  Hex notation allows zero compression  A string of repeated zeros is replaced with a pair of colons  FF05:0:0:0:0:0:0:B3 becomes FF05::B3  Can be applied only once in any address

12. © MMII JW RyderCS 428 Computer Networking12 Zero Suppression  0:0:0:0:0:0:128.10.2.1 becomes ::128.10.2.1  Looks quite similar to IPv4  12AB::CD30:0:0:0:0/60 says use first 60 bits and becomes  12AB00000000CD3

13. © MMII JW RyderCS 428 Computer Networking13 Basic IPv6 Address Types  Unicast – Destination address specifies a single computer. Route datagram along shortest path.  Anycast – Destination is a set of computers, possibly at different locations, that all share a single address. Route datagram along shortest path and deliver to exactly one member of the group (i.e. closest member)

14. © MMII JW RyderCS 428 Computer Networking14 Basic IPv6 Address Types  Multicast - Destination is a set of computers, possibly at different locations. One copy of the datagram will be delivered to each member of the group using hardware multicast or broadcast if viable.

15. © MMII JW RyderCS 428 Computer Networking15 Encoding IPv4 Addresses in IPv6 DATAGRAM IDENTIFICATION 16 bits IPv4 Address 0000........................ 0000 RESERVED 0000 FFFF IPv4 Address 0000......................... 0000 32 bits80 zero bits 16-bit field contains 0000 if node also has a conventional IPv6 address and FFFF if it does not.

16. © MMII JW RyderCS 428 Computer Networking16 General Form of IPv6 Datagram Base Header Extension Header 1 Extension Header N Data Optional 40 octets

17. © MMII JW RyderCS 428 Computer Networking17 IPv6 Base Header Format  See Base Header figure  Alignment changed from 32 bit to 64 bit multiples  Header length eliminated – Replaced with PAYLOAD LENGTH field  Size of source and destination addresses changed to 16 octets  Fragmentation information moved out of fixed fields in base header to extension header

18. © MMII JW RyderCS 428 Computer Networking18 IPv6 Base Header Format  TIME-TO-LIVE field changed to HOP LIMIT  SERVICE-TYPE field renamed to TRAFFIC CLASS and extended with FLOW LABEL field  PROTOCOL field replaced with a field that specifies type of next header

19. © MMII JW RyderCS 428 Computer Networking19 Base Header Format NEXT HEADERHOP LIMITPAYLOAD LENGTH FLOW LABELTRAFFIC CLASSVERS SOURCE ADDRESS DESTINATION ADDRESS 1604122431 Base Header Size: 4 + 4 + 16 + 16 = 40 Octets

20. © MMII JW RyderCS 428 Computer Networking20 Base Header Format  PAYLOAD LENGTH is length of all extension headers plus data  i.e. Total length – 40 octets (Base Header)  IPv6 datagram can contain up to 64K octets of data

21. © MMII JW RyderCS 428 Computer Networking21 Traffic Class  IPv4 SERVICE CLASS renamed to TRAFFIC CLASS  New IPv6 mechanism allows for resource reservation!  A router can associate with each datagram a given resource allocation  Abstraction called a FLOW  A FLOW is a path through an internet along which intermediate routers guarantee a certain level of quality of service

22. © MMII JW RyderCS 428 Computer Networking22 Traffic Class  FLOW LABEL in the base header contains a label that routers use to map a datagram to a certain specific flow and priority  Flows can also be used within an organization to manage network resources  Example  Two applications that need to send and receive video can establish a flow over which the bandwidth and delay are guaranteed

23. © MMII JW RyderCS 428 Computer Networking23 IPv6 Extension Headers Base Header NEXT=ROUTE Route Header NEXT=AUTH Auth Header NEXT=TCP TCP Segment Base Header NEXT=TCP TCP Segment Base Header NEXT=ROUTE Route Header NEXT=TCP TCP Segment One Base Header Two Base Headers Three Base Headers

24. © MMII JW RyderCS 428 Computer Networking24 IPv6 Fragmentation  As with IPv4, IPv6 arranges for destination to perform re-assembly  In IPv6 however, changes were made that avoid fragmentation by routers  IPv4 requires intermediate routers to fragment any datagram that is too large for the maximum transfer/transmission unit (MTU) of network over which it must travel  IPv6 fragmentation is end-to-end

25. © MMII JW RyderCS 428 Computer Networking25 IPv6 Fragmentation  No fragmentation done on intermediate routers  Source which is responsible for fragmentation has two choices  Use guaranteed minimum MTU (1280 octets)  Perform Path MTU Discovery  Identifies minimum MTU along path to the destination

26. © MMII JW RyderCS 428 Computer Networking26 IPv6 Fragmentation  Either case, the source fragments data  IPv6 fragmentation inserts a small extension header after the base header in each fragment DATAGRAM IDENTIFICATION FRAG. OFFSETNEXT HEADER 16082431 RESERVEDRS M 29 RS is set t 0 and reserved. M marks last fragment. ID unique for re-assembly. Fragments must be a multiple of 8 octets.