1. Wolfgang EffelsbergUniversity of Mannheim1 IP Version 6 The Next-Generation IP Protocol Wolfgang Effelsberg University of Mannheim September 2001

2. Wolfgang EffelsbergUniversity of Mannheim2 Outline 1. Remember IP Version 4? 2. IP Version 6 Fundamentals 3. IPv6 Header Format and Protocol Functions 4. Transition from Version 4 to Version 6

3. Wolfgang EffelsbergUniversity of Mannheim3 1. Remember IP Version 4? IP (Internet Protocol) – Layer 3 of the Internet A datagram protocol (connectionless) A host-to-host protocol Handles the fragmentation of large packets Does not do much else! No error control, no packet sequencing, no flow control, no congestion control

4. Wolfgang EffelsbergUniversity of Mannheim4 Format of IPv4 Datagrams (1)

5. Wolfgang EffelsbergUniversity of Mannheim5 Format of IPv4 Datagrams (2)

6. Wolfgang EffelsbergUniversity of Mannheim6 Addressing in IPv4 The IP address is hierachical, with the two fields netid and hostid. There is also a format for multicast (class D) For reasons hard to understand, four decimal numbers are used to describe an IP address: 10.0.0.0for Arpanet 128.10.0.0for a large Ethernet-LAN 192.5.48.0for a small LAN Class A Class B Class C 0 1 11 0 Netid Hostid 0 0 11 10 181624 31 Class D

7. Wolfgang EffelsbergUniversity of Mannheim7 2. IP Version 6: Fundamentals Motivation IPv4 networks running out of addresses  No more Class B addresses available  Hierarchical addressing wastes large chunks of the address space  CIDR (classless inter-domain routing) helpful but not a long- term solution Routing tables grow very large  More hierarchical levels desirable Fix bugs in the IPv4 design  After many years of experience design flaws of IPv4 should be removed

8. Wolfgang EffelsbergUniversity of Mannheim8 History of IPv6 1992: IETF publishes the Call for Proposals for „IP next generation“ (Ipng) 1994: SIPP (Simple Internet Protocol Plus) proposed by some researchers to the IETF 1995: Internet Draft „Internet Protocol, Version 6 (IPv6)“ becomes a Proposed Standard“ (9/95) and then an RFC1883 (12/95). Early prototypes implemented. 1996: IP Version 6 Backbone (6Bone) between some research labs, early products in the market 1998: RFC 2460, Draft Standard 2001: Widely implemented, but not very widely used because of considerable transition overhead for ISPs

9. Wolfgang EffelsbergUniversity of Mannheim9 Properties of IPv6 (1) New addresses  Address size 128 bits (one address for each bit in the universe!)  A deeper addressing hierarchy (Top Level Aggregator = address registration authority, Next Level Aggregator = large ISP, etc.). Leeds to smaller routing tables  Automatic address configuration integrated into IP Design bugs fixed  Fragmentation no longer supported. Replaced by „MTU discovery“ (maximum transfer unit) (!)  Header checksum removed (!)  All headers have a fixed size. Extension headers replace header options.  Hop limit replaces „time to live“

10. Wolfgang EffelsbergUniversity of Mannheim10 Properties of IPv6 (2) Better support for Quality-of-Service  Flow Labels allow the marking of all packets belonging to the same flow at the IP level  Traffic Class for Differentiated Services Full integration of IP multicast  Predefined multicast group addresses for special multicast functions  IGMP (Internet Group Management Protocol) fully integrated into ICMP (Internet Control Message Protocol)  All routers and end systems implement multicast IP. Tunnels will no longer be required.  Anycast also supported. Usage still a research issue. IP Security  Authentication and encryption are available at the IP layer

11. Wolfgang EffelsbergUniversity of Mannheim11 VersionTotal LengthHdr Len Prece- dence ToS Fragment OffsetIdentificationFlags Header ChecksumProtocolTime To Live Source Address Destination Address 3. IPv6 Header Format and Protocol Functions Red: removed Green: Moved to the extension header Yellow: renamed  precedence  class  total length  payload length  time to live  hop limit  protocol  next header IPv4: 20 Bytes in 13 fields

12. Wolfgang EffelsbergUniversity of Mannheim12 IPv6 Header Payload LengthNext HeaderHop Limit ClassVers.Flow Label Source Address Destination Address IPv6: 40 Bytes in 8 fields

13. Wolfgang EffelsbergUniversity of Mannheim13 Aggregatable Global Unicast Address The most important of many possible IPv6 address formats Top Level Aggregation (TLA)  Internet Naming Authority or very large ISPs with transit networks to which other ISPs are Next Level Aggregation (NLA)  Organisation on a lower level of the hierarchy  Multiple NLA levels possible Site Level Aggregation (SLA)  A single organisation, such as a large company 001TLA IDNLA IDSLA ID Interface ID 3132416 Public topologySite topology res. 8

14. Wolfgang EffelsbergUniversity of Mannheim14 Extension Headers Concatenation of extension headers  A small minimal header of fixed size, easy to process in routers  Flexible extensions for special purposes (such as source routing)  Eases the introduction of future extensions Last header in the chain specifies the type of the content encapsulated in IP (e.g., TCP, UDP).  Thus the PROTOCOL TYPE field of IPv4 is no longer needed.

15. Wolfgang EffelsbergUniversity of Mannheim15 Examples for Extension Headers IPv6-Header next header = TCP IPv6-Header next header = Routing IPv6-Header next header = Routing Routing-Header next header = TCP Routing-Header next header = Fragment Fragment- Header, next header = TCP TCP-Header + data TCP-Header + data TCP-Header + data

16. Wolfgang EffelsbergUniversity of Mannheim16 Stateless Automatic Address Configuration The router broadcasts parameters periodically to the multicast group of all hosts (router advertisement). Each host sends a router solicitation to the multicast group of all routers, a direct answer of the router follows. 3A01:203:405:1::1 FE80::C:D:1 3A01:203:405:1::C:D:1 3A01:203:405:1::/64, 3A01:203:405:1::1

17. Wolfgang EffelsbergUniversity of Mannheim17 4. Transition from Version 4 to Version 6 Duplicate protocol stacks  UDP/IPv4 and UDP/IPv6  TCP/IPv4 and TCP/IPv6 All IPv6 systems must also have an IPv4 protocol stack during the transition phase. application socket interface UDP for IPv4 layer 2 link TCP for IPv4UDP for IPv6TCP for IPv6 IPv6

18. Wolfgang EffelsbergUniversity of Mannheim18 IPv4-Compatible Address Allows IPv6 implementations to work with old v4 addresses Can be used by IPv6 systems to communicate with other IPv6 systems by TUNNELS IPv4 address 0... 0

19. Wolfgang EffelsbergUniversity of Mannheim19 Tunneling IPv4-Router hand-configurated tunnel (Host  Router or Router  Router) Automatically config. tunnel (Router  Host, Host  Host) Tunneling means the encapsulation of an IP packet into another IP packet which will have a new, different IP destination address. At the end of the tunnel the inner IP packet is removed from the „envelope“. In this way an IP packet can be transmitted over pieces of the network which it could otherwise not cross.

20. Wolfgang EffelsbergUniversity of Mannheim20 References C. Huitema: IPv6 - The New Internet Protocol, second edition, Prentice Hall, 1998 W. Stallings: IPv6: The New Internet Protocol, IEEE Communications, Vol. 34, No. 7, S. 96-108 R. Fink: IPv6 - What and Where it is, Cisco Internet Protocol Journal, März 1999 W. Stallings: IP Security, Cisco Internet Protocol Journal, März 2000 T. Braun: Internet Protocols for Multimedia Communications, Part I, IEEE Multimedia, Vol. 31, No. 9, S. 85-90 T. Braun: IPng: Neue Internet-Dienste und Virtuelle Netze, dpunkt 1999 (in German)