1. Bjorn Landfeldt, The University of Sydney 1 NETS 3303 IPv6 and migration methods

2. Bjorn Landfeldt, The University of Sydney 2 Expected outcomes Understanding the background –What’s wrong with v4 –How does v6 address this What else does v6 introduce Knowing about issues with transition from v4 to v6 Understanding transition Mechanisms

3. Bjorn Landfeldt, The University of Sydney 3 IPv6, Background IPv4 address space 2 32 –About half assigned –Introduction of 3G, embedded devices etc. Clearly, we need a larger address space

4. Bjorn Landfeldt, The University of Sydney 4 IPv6, Background IPv6 address space 2 128 Some other improvements over v4 –Simple fixed 40 byte header (routing) –Improved encryption and authentication –Address auto-configuration

5. Bjorn Landfeldt, The University of Sydney 5 IPv6 Header 0 13 32 51725 VersionTraffic classFlow label Payload lengthNext headerHop limit Source address Destination address

6. Bjorn Landfeldt, The University of Sydney 6 IPv6 Extension Headers Hop-by-hop Options –Information for routers, e.g. jumbogram length Routing –Source routing list Fragment –Tells end host how to reassemble packets Authentication (for destination host) Encapsulating Security Payload –For destination host, contains keys etc. Destination options (extra options for destination)

7. Bjorn Landfeldt, The University of Sydney 7 IPv6 Addressing in theory, 1500 or so addresses per square meter of earth’s surface (2 ^128 is big number) Notation format FEDC:BA98:7654:3210:0000:0000:0000:0089 Interoperability with IPv4 –Use prefix 0000 0000 –0000 0000 0000 v4: IPv4 host to IPv6 host –0000 0000 FFFF v4: Tunnel v6 over v4, the v4 address is the tunnel end point. Thus, v4 addresses can be embedded in v6 addresses However, if a v6 host needs to talk to a v4 host it still needs to occupy a v4 address!!!!!!!!

8. Bjorn Landfeldt, The University of Sydney 8 Local Addresses link-local used on single link (0xfe) 1111111010 | 0 (54 zeroes total) | if ID (64 bits) –auto-address configuration –neighbor discovery –no routers present site-local used within site only 1111111011 | 0 (38) | subnet (16) | if ID –routers do not forward outside site –intended to replace “intranet” addrs, 10.0.0.0, etc.

9. Bjorn Landfeldt, The University of Sydney 9 address high-level architecture FP, format prefix at FRONT is variable length allocation reserved address-space-slice reserved 00000000 1/256 unicast 001 1/8 link-local unicast 1111 1110 10 1/1024 site-local unicast 1111 1110 11 1/1024 multicast 1111 1111 1/256

10. Bjorn Landfeldt, The University of Sydney 10 IPv6 Hierarchy IPv4 address space completely flat (no geographic dependency) IPv6 semi-hierarchical (compare telephone numbers) –Top level routers have address ranges with regional meaning in routing tables –Next level routers have knowledge of ranges to organisations (corporations, ISPs etc.) –Site level routers have host and network specific routing tables

11. Bjorn Landfeldt, The University of Sydney 11 IPv6 Autoconfiguration Two methods available –Dynamic Host Configuration Protocol, DHCP –Neighbour Discovery, ND Host issues Router Solicitation message on “all routers multicast address” Router answers with Router Advertisement message Both ICMPv6 Advertisement {subnet prefix:hosts 48 bit MAC address}

12. Bjorn Landfeldt, The University of Sydney 12 Migration Methods dual-stacks, IPv6 and IPv4 Tunnelling NAT –Traditional NATs –RSIP and SIIT –REBEKAH-IP transition likely to take a very long time

13. Bjorn Landfeldt, The University of Sydney 13 Tunnelling tunnels: IPv6 internets can tunnel IPv6 packets over IPv4 networks, “short-term” if and when more IPv6, then IPv4 tunnelled over IPv6

14. Bjorn Landfeldt, The University of Sydney 14 Tunnelling Data UDP IPv6 Dual stack routers Data UDP IPv6 Data UDP IPv6 Data UDP IPv6 v6 v4 v6 V4 added V4 removed Host 2 Host 1

15. Bjorn Landfeldt, The University of Sydney 15 NAT Address realm 1, IPv6 Address realm 2, IPv4 Translation

16. Bjorn Landfeldt, The University of Sydney 16 Classical NAT NAT has pool of public IPv4 addresses One public address assigned to each private node on packet arrival at NAT Address held until session closed or timeout

17. Bjorn Landfeldt, The University of Sydney 17 Classical NAT Is there a problem with assigning addresses this way?

18. Bjorn Landfeldt, The University of Sydney 18 Classical NAT Answer: This does not scale at all.

19. Bjorn Landfeldt, The University of Sydney 19 NAPT Private hosts share a public IP address Each identified flow is assigned a unique sender port number Return packet translated to private address and port depending on dst. Port number

20. Bjorn Landfeldt, The University of Sydney 20 NAPT Is there a problem with this approach? –Hint: reachability

21. Bjorn Landfeldt, The University of Sydney 21 NAPT Network initiated communication not possible. We cannot separate hosts with same IP address.

22. Bjorn Landfeldt, The University of Sydney 22 ALG Another problem: –In-band signalling SIP HTML Exchange ICQ Netmeeting Etc.

23. Bjorn Landfeldt, The University of Sydney 23 ALG Solution: ALG –Application specific filtering –Reads and rewrites payload Problems –Security? –Who will implement ALG?

24. Bjorn Landfeldt, The University of Sydney 24 RSIP Private realm host incorporates RSIP client RSIP client requests public IP address from RSIP server RSIP server assigns address to client and sets up IP tunnel Client configures private host with public address and uses tunnel to RSIP server

25. Bjorn Landfeldt, The University of Sydney 25 RSIP Two versions corresponding to classical NAT and NAPT, RSA-IP and RSAP-IP Advantage: –No ALGs necessary Disadvantage: –Network initiated communication still impossible

26. Bjorn Landfeldt, The University of Sydney 26 REBEKAH-IP Each flow has a unique address in the Internet –Sender and receiver IP addresses and port numbers Dynamically assign a combination rather than occupying a specific address or port

27. Bjorn Landfeldt, The University of Sydney 27 REBEKAH-IP Switch traffic depending on sender and receiver IP addresses and port numbers –Assign same public address to multiple private hosts –Rely on a series of dispatch mechanisms for resolving clashes in advance

28. Bjorn Landfeldt, The University of Sydney 28 REBEKAH-IP Use RSIP client server concept to avoid ALG for application data Add an ALG to DNS Have DNS assign public addresses to private nodes Supports Network initiated and terminated traffic

29. Bjorn Landfeldt, The University of Sydney 29 REBEKAH-IP Address realm 1 Address realm 2 RS Pool of public IP addresses DNS/ALG Signalling Data

30. Bjorn Landfeldt, The University of Sydney 30 REBEKAH-IP DNS refinement: –Return Authoritative address to first query (make sure to get host address) –Implement SRV record for optimised client Client optimisation –Ask for “ANY” record –Read port to use in answer

31. Bjorn Landfeldt, The University of Sydney 31 REBEKAH-IP Scalability: –NAPT: C =X*2 16 –REBEKAH-IP: 2 16 *2 16 *(2 32 -X)*X; X*2 16 > C > X*2 96 C = number of possible combinations X = number of available IP addresses

32. Bjorn Landfeldt, The University of Sydney 32 Further reading RFC 2460 Internet Protocol, Version 6 (IPv6) Specification. S. Deering, R. Hinden. December 1998. RFC 2663 IP Network Address Translator (NAT) Terminology and Considerations. P. Srisuresh, M. Holdrege. August 1999. REBEKAH-IP paper from http://mobqos.ee.unsw.edu.au