1. IPv6
Prepared by:
ydrugalya@gmail.com

2. Agenda
• IPv6 features overview
• IPv6 addressing
• Integration and co-existing strategies
• IPv6 application development
• A Big Picture
• References

3. History
• 1974 Cerf and Kahn developed TCP/IP for
ARPA.
• NSF (end of 70-th)
• 1992 – RFC 1550. 21 response. 7 left. CLNP.
• 1993. 3 proposals left (Deering, Francis, Katz
and Ford). SIPP.
• SIPP  IPv6 (IPv5 – already allocated)

4. NAT
192.168.0.100 ->.. -> 74.125.87.99(google.com)
192.168.0.100 (5043, 80) 
192.168.0.1 / 157.55.1.10 (666, 80) 
74.125.87.99(google.com)

5. NAT

6. Why NAT is bad
• This was a temporary solution from the beginning
• NAT keep us away from transparent connection
• NAT violates security and principle of packets
consistency
• NAT was blocking development of transparent
applications
• Double/triple NAT translation is very ugly thing

7. Requirements
• Larger address space
• Simpler protocol for faster routing processing
• Better security
• Better QoS
• Extensibility
• Auto configuration
• Better Multicast and Anycast abilities
• Better support for mobile devices
• Coexisting

8. New Header Format(RFC 2460 )

9. IPv6 Header Fields
• Version – always 6 for IPv6
• Traffic class – similar to ToS in IPv4. Each traffic class
can be managed differently, ensuring preferential
treatment for higher-priority traffic on the network.
Not widely used.
• Flow label. Experimental. Idea reserve throughput for
flow between two hosts. Virtual channel.
• Next header – tells which one from 6 extension
headers follows
• HOP Limit – ex TTL.
• Source/Destination addresses

10. Comparing IPv4 and IPv6 headers
• IHL – removed
• Protocol – removed
• Removed all fields related to fragmentation
• TTL replaced by Hop limit field.
• Header checksum - deprecated (upper level checksum can do it).

11. Extension Headers*

12. Extension Headers
Header Type Purpose
Hop-By-Hop Optional data that each host must examine(Deprecated)
Routing Causes packet to visit specific hosts on its way to destination
Fragment Contains fragment identification, offset flags
Destination Options Processed only by destination host
Authentication Sender verification
Encapsulating Security
Indicates that the rest of payload is encrypted
Payload

13. Stateless and Stateful Address
Configuration
• Statefull address configuration
– DHCP for IPv6
• Stateless address configuration
– No DHCP server
– Automatic link-local address configuration

14. IPv6 Address format
RFC 2373
2001:05c0:1000:000b:0000:0000:0000:9eaf

2001:5c0:1000:b::9eaf
http://[2620:0:1cfe:face:b00c::3]

15. IPv6 address types
- Unicast – address for single interface
- Global
- Site-local
- Link-local
- Anycast – address of set of interfaces
- Multicast – scoped address of group of
interfaces
RFC 4291

16. Global Unicast address format
2620:0:1cfe:face:b00c::7

17. Site-Local address format
FEC0::3:260:8FF:FE52:F9D8

18. Link-local format
EUI-64(RFC 2373) VS Random number

19. Multicast address format
• ff02::1 - all nodes in local segment
• ff02::2 - all routers in local network segment
• FF01::2 - node local scope all routers
• FF02::2 - link-local scop all-routers

20. IPv4 compatible IPv6 address
deprecated

21. IPv4 mapped IPv6 address
RFC 4038

22. Integration and co-existing strategies
• Dual-stack
• IPv6 over IPv4 tunnels
• Dedicated data links

23. Dual-stack

24. Popular transition technologies
• Static 6 over 4 tunnels
• Automatic 6to4 Tunnel.
– 6to4
– Teredo
– ISATAP
– go6.net
– SixXS
IPv6 Transition Technologies

25. IPv6 over IPv4 tunnels

26. 6to4*
Idea:
- Encapsulate IPv6 packet into IPv4 packet
Example:
IPv4 address: 16.24.244.69 -->
2002:1018:f445::1018:f445

27. Teredo*
Idea:
- encapsulate IPv6 into UDP
- encapsulate UDP port and ipv4 into ipv6
address
RFC 4380 . Example
2001:0:5ef5:79fd:34a0:3750:e0e0:8ed1

28. ISATAP
RFC 4214

29. IPv6 Application development

30. IPv6 Application development
IPv6 Guide for Windows Sockets Applications
Checkv4.exe
Main idea: make your application dual stack
- use agnostic data structures
- change function calls
- remove hardcoded addresses
- change UI
RFC 4038

31. IPv6 Application development
Data structures
Data structures
sockaddr_in  sockaddr_storage
Shims: getPort, getSockAddrBytes, getAddrLen, etc.
int getPort(sockaddr_storage& addr) {
switch(addr.ss_family) {
case AF_INET:
return ntohs ( reinterpret_cast<sockaddr_in*>(&addr)->sin_port );
case AF_INET6:
return ntohs ( reinterpret_cast<sockaddr_in6*>(&addr)->sin6_port );
default:
throw exception;
}

32. IPv6 Application development
Function calls
#if !defined(IPV6_V6ONLY)
# define IPV6_V6ONLY 27
#endif
setsockopt(sockfd, PPROTO_IPV6, IPV6_V6ONLY,
(char *)&off, sizeof(off) );
gethostbyname  getaddrinfo
gethostbyaddr getnameinfo

33. Troubleshooting
netsh interface ipv6 show address
netsh interface ipv6 show neighbors
netsh interface ipv6 delete neighbors
netsh interface ipv6 show destinationcache
netsh interface ipv6 delete destinationcache

34. Troubleshooting

35. BIG PICTURE

36. IPv6 deployment status

37. Necessity vs Inertness

38. References
• IPv6 Learning Roadmap
• IPv6 Guide for Windows Sockets Applications
• www.ipv6.com
• Test your IPv6 connectivity
• Google IPv6 Conference 2008: What will the IPv6
Internet look like?
• SixXS - IPv6 Deployment & Tunnel Broker
• Cool IPv6 stuff
• icmpv6x