© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. © The McGraw-Hill Companies, Inc. IP version 6 Asst. Prof. Chaiporn Jaikaeo, Ph.D. Computer Engineering Department Kasetsart University, Bangkok, Thailand Adapted from the notes by Lami Kaya and lecture slides from Anan Phonphoem

2 What is wrong with IPv4 ? Internet growth New applications – Real time app. Network Changes Need for corporations

3 Internet Growth

4 IP Address Allocation IANA  RIRs  ISPs IANA – Internet Assigned Numbers Authority RIR – Regional Internet Registrar Source: wikipedia.org

5 Number of Free /8s Source: wikipedia.org

6 NAT to the Rescue… Or not? NAT R / ISP /16 The Internet

7 The NAT “Problem” Internet NAT ? NAT breaks end-to-end connectivity model Complicate communication between hosts

8 Rationale for IPv6 IPv4 address space consumption Last blocks have already been allocated Unused addresses reclaimed Loss of “end to end” connectivity Widespread use of NAT due to ISP policies and marketing Additional complexity and performance degradation

Needs for IPv6 9

10 IPv6 Feature Summary Increased size of address space Header simplification Extended Address Hierarchy Auto-configuration / Renumbering Quality of Services (QoS) IPSec (As for IPv4)

11 IPv6 Addressing Model Unicast single interface Anycast any one (among many) same location replicate services (servers) Multicast all of a group of interfaces replaces IPv4 “ broadcast ” See RFC 3513

12 IPv4 vs. IPv6 Addresses IPv4: 32 bits 2 32 addresses = 4,294,967,296 addresses = 4 billion addresses IPv6: 128 bits addresses? = 340,282,366,920,938,463,463,374,607,431,770,000,000 = 340 billion billion billion billion addresses? No, due to IPv6 address structure…

13 IPv6 Address Presentation 8 groups of 4 hexadecimal digits Each group represents 16 bits Separator is “:” Case-independent 128 bits 2001:0DA8:E800:0000:0260:3EFF:FE47:0001

:0DA8:E800:0000:0000:0000:0000: :0DA8:E800:0000:0260:3EFF:FE47:0001 IPv6 Address Presentation 2001:DA8:E800:0:260:3EFF:FE47:1 2001:0DA8:E800:0000:0000:0000:0000: :0DA8:E800:0000:0260:3EFF:FE47: :DA8:E800::1

15 Special Addresses Unspecified address 0:0:0:0:0:0:0:0  :: Source add. (when own add. is unknown) Loopback address 0:0:0:0:0:0:0:1  ::1 For testing Datagram is delivered to local machine

Unicast Address Scopes Global scope Start with 001 (binary) Link-local scope Only used within directly attached network Belonging to FE80::/10 block 16 0 (54 bits)Interface ID (64 bits) bits 96dbc9FFFE0016fe 94dbc90016fe U = 0: not unique U = 1: unique xxxxxxUx Prefix provided by service provider Subnet ID 4816 Interface ID

Unicast Address Scopes Loopback address (::1/128) also has link- local scope Tied to the host’s loopback interface 17

Multicast Address Format Multicast addresses define groups of receivers Similar to IPv4’s class D addresses flagGroup ID 8 bits112 bits scope 44

19 IPv6 header IPv6 header is simpler than IPv4 IPv4: 14 fields, variable length (20 bytes +) IPv6: 8 fields, fixed length (40 bytes) Header fields eliminated in IPv6 Header Length Identification Flag Fragmentation Offset Checksum Header fields enhanced in IPv6 Traffic Class Flow Label

20 Basic Headers IPv4 IPv6

21 Structure of Datagram Base Header is fixed 40 Octets long Options are in an extension header Several extension headers Base Header Extensions TCP/UDPData

22 Basic Headers (Fields) Version (4 bits) – only field to keep same position and name Class (8 bits) – new field Flow Label (20 bits) – new field Payload Length (16 bits) – length of data, slightly different from total length Next Header (8 bits) – type of the next header, new idea Hop Limit (8 bits) – was time-to-live, renamed Source address (128 bits) Destination address (128 bits)

23 Header Simplification Fixed length of all fields, not like old options field – IHL, or header length irrelevant Remove Header Checksum – rely on checksums at other layers No hop-by-hop fragmentation – done at hosts only (using Path MTU Discovery) Add extension headers – next header type (sort of a protocol type, or replacement for options) Basic Principle: Routers along the way should do minimal processing

24 Extension Headers Types Routing Header Fragmentation Header Hop-by-Hop Options Header Destinations Options Header Authentication Header Encrypted Security Payload Header Base Header Extensions TCP/UDPData

IPv6 Extension Headers Example 1: no extension header Example 2: with a routing header 25 Next header = 6 (TCP) TCP hdr + payload Next header = 43 (routing) TCP hdr + payload Next header = 6 (TCP)

26 IPv6 Transition Dual stack hosts Two TCP/IP stacks co-exists on one host Supporting IPv4 and IPv6 Client uses whichever protocol it wishes

27 IPv6 Transition IPv4IPv6 ?? IPv4 TCP/UDP Application IPv6 Link

28 Application Transport Network TCP/IP Protocol Stack Application Transport Network Data Link Physical Data Phy Data Phy Physical Data Link

29 IPv6 tunnel over IPv4 IPv6 Transition IPv4 Network IPv6 IPv6 Header Data IPv4 Header IPv6 Header Data IPv6 Header Data tunnel