1. Introduction to IPv6 © J. Liebeherr, 2012, All rights reserved

2. Internet Protocol: Which version? There are currently two versions of the Internet Protocol in use for the Internet IPv4 (IP Version 4) Specified in 1980/81 (RFC 760, 791) Four byte addresses Universally deployed Problem: Address space almost exhausted IPv6 (IP Version 6) Specification from 1998 (RFC 2460) Not interoperable with IPv4, but not fundamental changes 128 bit addresses Problem: Not widely used (yet?)

3. Slow adoption of IPv6 IPv6 is available since 15 years, and almost all operating systems now support it But IPv6 is not yet widely adopted Measurements at Internet Exchange Point in Amsterdam: linearsemi-log

4. How many addresses in IPv6? IPv4 Addresses: –2 32 = 4,294,967,296 ≈ 4 billion IPv6 Addresses: –2 128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 ≈ 3.4 x 10 38 Surface area of Earth: 510,072,000 km 2 Size of Atom: 10 -10 m = 0.1 nm = 1 Angstrom (Å) “Area of Atom”: 1 square angstrom (Ų)= 10 -20 m 2  Number of atoms on Earth’s surface: 510,072,000 km 2 / 10 -20 m 2 = 5.1 x 10 31  Number of IPv6 addresses for each atom on the surface of the Earth: ~ 6.7 million

5. IPv6: Summary of Features 128-bit interface addresses Streamlined header format with extension headers Security options Node Mobility No broadcast (therefore, no ARP) No NAT (at least no need is seen) Others: Anycast addresses Minimum MTU is 1280 bytes Jumbogram extensions allow datagrams up to 2 32 -1 bytes Type field of Ethernet frames with IPv6 packets is 86DD

6. Protocols not affected by IPv6 transition Protocols above and below network layer are not affected: –Applications (e.g., web server, mail server, etc.) Additional considerations for support of both IPv4 and IPv6 –Transport protocols (i.e., TCP, UDP) –Link layer protocols (i.e., Ethernet)

7. Protocols and services with modifications Some protocols need to be slightly modified to account for IPv6 addresses and requirements of IPv6 (e.g., no broadcast) –Routing Protocols RIPng, OSPv3, MP-BGP –DNS –No change to structure of names or server hierarchy –New record type (AAAA) for entries with IPv6 addresses –DHCPv6 –Similar to DHCP, but without broadcast Changes are sometimes limited to allowing space for larger IP addresses and prefixes, and replacing broadcast by multicast Some considerations are needed for simultaneous support of IPv4 and IPv6

8. IPv6 Routing Protocols RIPng Based on RIPv2 Updated features: IPv6 prefix, next-hop IPv6 address, uses the multicast group FF02::9 for updates, uses UDP port 521 OSPFv3 Based on OSPFv2, with enhancements Updated: Distributes IPv6 prefixes, multiple addresses per interface, authentication uses IPsec MP-BGP Multiprotocol extension of BGP-4 Can carry informaton on IPv6, but also other protocols

9. IPv6 Packet Format

10. IPv6 Header Minimum size: 40 bytes Header is multiple of 8 bytes long

11. IPv6 Packet header 11 IPv6 has a simplified header structure: –Headers have fixed size –No fragmentation (but available via header extensions) –No header checksum Most fields play a similar role as in IPv4: New Features: –Extension headers –Flow label –Authentication and Privacy IPv6 … similar to … IPv4 Version Traffic classDiffServ Payload lengthTotal length Next HeaderProtocol Hop LimitTTL

12. Extension Headers Instead of header options, IPv6 allows to concatenate optional headers to the main header Extension Headers: Security: Authentication Fragmentation Routing Payload Header (TCP, UDP, …)

13. IPv6 Addresses

14. Convention for writing IPv6 addresses IPv6 addresses are written as hexadecimals “Blocks” of 16 bits are separated by colons. Abbreviation Rules: 1.Leading zeroes in a block can be omitted FE80:0000:0000:0000:002A:0000:FE04:0A81  FE80:0:0:0:2A:0:FE04:A81 2. One (but only one) contiguous block with all zeros can be replaced by a double colon FE80:0:0:0:2A:0:FE04:A81  FE80::2A:0:FE04:A81 FE80:0:0:0:2A:0:FE04:A81  FE80:0:0:0:2A::FE04:A81 Best abbreviation result:

15. Types of IPv6 Addresses Binary PrefixIPv6 Prefix Multicast1111 FF00::/8 Link-local unicast1111 1110 10FE80::/10 Unique Local unicast Address (ULA) 1111 1100 1111 1101 FC::/8 FD::/8 Global unicasteverything else currently allocated global unicast addresses 0012000::/3

16. Special IPv6 Addresses IPv4-mapped IPv6 addresses allow the use of IPv4 addressses in an IPv6 context. –IPv4 part of the address can be written in dotted decimal notation –Example: ::FFFF:128.100.11.2 Binary PrefixIPv6 Prefix Unspecified (not assigned, indicates absence of an address) 00…0 (128 bits)::/128 Loopback00…1 (128 bits)::1/128 IPv4-mapped IPv6 addresses::FFFF:0.0.0.0/96

17. Structure of a global unicast address Global routing prefix  is allocated from ISP or Internet registry  has typical length (N) of 32-64 bits  All current allocated prefixes start with 001 (binary). Subnet ID defines the subnetwork Interface ID  has length 64 bits (Exception: When routing prefix starts with 000, length of Interface ID can be different)  is built using EUI-64 format

18. EUI-64 Address IEEE EUI-64 is essentially a 8-byte MAC address There is a method to create EUI-64 address from a 48-bit MAC address Modified EUI-64 simply flips the 7 th bit from the first byte The modified EUI-64 address is used as IPv6 Interface ID

19. IPv6 Address Allocation The process for allocating address blocks (prefixes) is as with IPv4: IANA allocates prefixes of /23 up to /12 to RIRs RIR allocates prefixes of /32 up to /19 to LIR, ISP, or End users LIR/ISP obtains prefixes of /64 up to /48 There can be a National Internet Registry (NIR) between RIR and LIR/ISP IANA End user allocates assigns End user assigns RIR LIR (ISP)

20. Currently available Global Unicast Addresses RIRAllocated IPv6 prefix APNIC2400::/12 ARIN2600::/12 ARIN2800::/12 RIPE2A00::/12 AfriNIC2C00::/12 Allocated IPv6 prefix IANA2000::/3 Note: Several additional smaller blocks (longer prefixes) have been assigned.

21. IPv6 Multicast Address Four flags: 0RPT 1. 0 : first flag is always zero 2. T=0 : permanent address (otherwise non-permanent) 3. P=1 : Group ID based on network prefix 4. R=1 : Group ID contains address of rendezvous point Scope defines area of validity of group ID (local to global) Predefined multicast addresses exist All nodes: FF01:00:1, FF02:00:1 All routers: FF01:00:2, FF02:00:2 : FF05:00:2

22. Destination MAC address of Ethernet frames with IPv6 multicast payload: –First two bytes are set to 0303 (hex) –Last 4 bytes are set to last four bytes of IPv6 multicast address Mapping IPv6 Multicast to Ethernet 22

23. Link-Local Unicast Addresses Used during autoconfiguration when no router is present IPv6 requires that each interface has link local address, even if the interface has a routable address Link Local address is used whenever communicating with nodes on same subnet Packets with this address are local to a subnet (not forwarded by routers) Issue: Since all link-local addresses have the same prefix, how does a node pick the correct outgoing interface? –An additional identifier is appended to address  Zone Index –Routing tables use zone index for all link-local addresses –Zone index can be index or name of interface: fe80::21f:f3ff:fec5:dc47%1, fe80::21f:f3ff:fec5:dc47%en1

24. Unique Local Unicast Addresses (ULA) Address bloc: FC00::/7 Global ID is randomly selected Addresses for communication within a domain, e.g., enterprise network Packets with this address may be routed within an administrative domain, but are not globally routable x =1: Global ID is locally assigned x =0: not defined

25. University of Toronto IPv6 prefix of University of Toronto: 2606:FA00::/32 Address block is allocated from ARIN Subnet ID Interface ID from: to:

26. Exercise with IPv6 Multicast Addresses Consider the IPv6 prefix: 2001:0AE8:0000:0000:BC30:0000:0000:0000/60 The following are permitted abbreviations of the prefix: 2001:AE8::BC30:0:0:0/60 2001:AE8:0:0:BC30::/60 The following are not permitted abbreviations of the prefix: 2001:AE8::BC30/60 2001:AE8::BC30::/60 2001:AE8:0.0:BC3::/60

27. IP Address Configuration

28. Enhanced Role of ICMPv6 Functions of ARP and IGMP are performed by ICMPv6 messages –NDP: Neighbor Discovery Protocol –MLD: Multicast Listener Discovery 28 IPv4IPv6

29. Neighbor Discovery Protocol Uses several ICMPv6 messages types: Router Solicitation / Router Advertisement, Neighbor Solicitation / Neighbor Advertisement, Route Redirect Functions: –Router/Prefix/Parameter Discovery –Address Autoconfiguration –Address Resolution –Next-Hop Determination –Duplicate Address Detection –Neighbor Unreachable Detection

30. Dynamic Assignment of IPv6 Addresses Static IP configuration still exists DHCPv6 Similar to DHCP for IPv4 Requires a server (  “stateful”) For networks with central control of address assignment Stateless Autoconfiguration Uses ICMPv6 messages Nodes select their own interface ID No need for server (  “stateless”) For networks without central control of address assignment

31. 31 ICMP Router Solicitation ICMP Router Advertisement Router Solicitation sent to the “all routers” multicast group Router Advertisement sent to “all nodes” multicast group Router Advertisement contains: –Network prefix –MTU –Default Hop limit –Router advertisement may tell host to use DHCP

32. 32 ICMP Neighbor Solicitation ICMP Neighbor Advertisement Functions: Replacement for ARP Duplicate address detection Messages sent to “solicited node” multicast group, or via unicast

33. When a router detects that a packetshould have gone to a different (better) router, the router (here R2) forwards the packet to the correct router sends an ICMP redirect message to the host Host uses ICMP message to update its routing table 33 Routing Redirect R1

34. Stateless Address Autoconfiguration Stateless address autoconfiguration can set IP parameters of a node without a server or manual configuration: 1.Upon startup, a node create link-local addresses for each IPv6 interface from MAC address 2.Test uniqueness by sending a Neighbor Solicitation to the created address –If a host replies with Neighbor Advertisement, address is in use –If no response, address can be used 3.Send “ICMP Router Solicitation” to “all routers” group –Router replies with Router advertisement containing prefix, MTU, and other information 4.Node creates a globally routable IP address using the prefix sent by the router, and the Interface ID from the link-local address

35. IPv6 Transition

36. IPv6 Transition Mechanisms The adoption of IPv6 has been very slow Deployment of IPv6 will be incremental (gradual) For the foreseeable future, IPv4 and IPv6 must co-exist IPv6 transition mechanisms seek to facilitate the transition to IPv6 and ensure coexistence of IPv4 and IPv6 on the same network IP/ICMP translation Dual Stack Tunneling (6bone, 6to4, 6rd, …) many more

37. IP/ICMP translation Refers to a translation of ICMP and IP packet headers between v4 and v6 Takes advantage of IPv4-mapped IPv6 addresses Works similarly to NAT Other scenarios: IPv6 Network  IPv4 Network, IPv4 Network  IPv6 Internet, IPv4 Internet  IPv6 Internet

38. Tunneling IPv6 “islands” can be connected across IPv4 network by encapsulating them in IPv4 packets 38

39. Tunneling IPv6 networks connect via IP tunnels With tunneling, IPv6 packets are encapsulated by IPv4 header (IP-in-IP encapsulation)

40. Dual Stack Dual Stack means that IPv6 enabled hosts, servers, and routers support IPv4 and IPv6 in parallel Allows co-existence of IPv4 and IPv6 devices on the same network Dual stack transition is used by enterprise/university networks

41. IPv6 Topics not covered here Anycast Security (Authentication headers) Mobile IP