CIT 384: Network Administration

1. CIT 384: Network Administration IPv6 CIT 384: Network Administration

2. Topics • Why IPv6? • IPv6 Addressing • Stateless autoconfiguration • Special Addresses • IPv4 to IPv6 Transition CIT 384: Network Administration

3. Why IPv6? We’re running out of IP addresses • IPv4 lifetime extended by CIDR and NAT. • Only 14% of addresses are unallocated. • At current rate, all addresses used by 2011. Solutions • Reclamation: reclaim unused/underused spaces. • We allocate a /8 every few months, so too slow. • Address space fragmentation increasing rtr table sizes. • Upgrade to IPv6 with its 128-bit addresses. CIT 384: Network Administration

4. IPv4 to IPv6 Transition CIT 384: Network Administration

5. IPv4 to IPv6 Transition CIT 384: Network Administration

6. Why IPv6? Security • IPsec is part of IPv6 backported to IPv4. Mobility • Better support for mobile devices. QoS • Support for multimedia QoS features. Header Improvements • No need to recalculate checksum at each hop. CIT 384: Network Administration

7. IPv4 vs IPv6 Addresses CIT 384: Network Administration

8. IPv4 and IPv6 Address Composition CIT 384: Network Administration

9. IPv6 Prefixes CIT 384: Network Administration

10. Global Route Aggregation • Grouping by geographic region • Grouping by ISP within geographic region • Grouping by customer within ISP CIT 384: Network Administration

11. Global Routes Example CIT 384: Network Administration

12. IPv6 Prefix Assignment Example CIT 384: Network Administration

13. Subnetting IPv6 Addresses Company 1 is assigned a /48 Needs 4 subnets Uses 16 of the 80 provided bits for subnets. CIT 384: Network Administration

14. Subnetting IPv6 Addresses Possible subnets: 216 Possible hosts/subnet: 264 Allows use of automatic IPv6 address assignment. CIT 384: Network Administration

15. IPv6 Address Format with EUI-64 Autoconfigure IPv6 addr using MAC EUI-64 = MAC + FFEE Universal/Local bit: 1=local, 0=burned in MAC CIT 384: Network Administration

16. Stateless Autoconfiguration Use Neighbor Discovery Protocol (NDP) • Router solicitation (RS) multicast messages • Router responds with IPv6 prefix, router IPv6 • IPv6 = IPv6_prefix + EUI-64 • Another part of NDP replaces ARP DHCPv6 is stateful alternative • Works like DHCP for IPv4 • Must maintain client state (leases) • Can use stateless DHCP to provide DNS servers CIT 384: Network Administration

17. IPv6 Address Types Unicast • Unicast addresses like IPv4. Multicast • Represents a group of devices. Anycast • Used when message can be sent to any member of a group but does not need to be sent to all. CIT 384: Network Administration

18. IPv6 Special Addresses Reserved Addresses Addrs beginning with 00 are reserved. 1/256 of entire address space. Private Addresses Addrs beginning with FE[8-F] are private Similar to RFC 1918 IPv4 private addresses. Loopback Address 0:0:0:0:0:0:0:1 is the one and only loopback addr Unspecified Address 0:0:0:0:0:0:0:0 used when a dev does not know own addr CIT 384: Network Administration

19. Private Address Types Site Local • Scope is an entire site or network. • Local routers will fwd, internet routers will not. • Begin with FE[C-F] Link Local • Scope is local subnet. • Routers will not fwd link local addresses. • Used for address configuration, resolution, ND. • Begin with FE[8-B] CIT 384: Network Administration

20. Stateless Autoconfiguration Process • Host computes its IPv6 link local address. • Host sends an NDP router solicitation (RS) Source addr: link local address Dest addr: FF02::2 all-routers multicast • Routers reply w/ router advertisement (RA) Reply includes prefix + router IP address • Host builds its unicast IP address • Prefix from RA + EUI-64 • Host asks stateless DHCP svr for DNS svr IPs CIT 384: Network Administration

21. IPv6 Routing Protocols Routing protocol updates • Support for larger IPv6 addresses. • Use of IPv6 multicast addresses • Advertise link local IP as next hop. CIT 384: Network Administration

22. IPv6 Transition Dual Stacks • Devices that use both IPv4 and IPv6 at once. • Can use both protocols during transition. • Useful for intranets. Tunneling • Encapsulate IPv6 packets in IPv4 packets. • Manual tunnels can be configured btw routers. • Dynamic 6to4 tunnels can be created as needed using public 6to4 relay routers. CIT 384: Network Administration

23. IPv6 to IPv4 Tunnel CIT 384: Network Administration

24. NAT-PT NAT-Protocol Translation • Translates IPv4/6 addresses at boundary. • Dynamically assigns IPv4 addrs to IPv6 nodes. • Needs a pool of IPv4 addresses. • Can use PAT for greater efficiency. ALGs (Application Level Gateways) • Some protocols embed IPs w/i payload. • NAT-PT must use ALGs for DNS, FTP, etc. CIT 384: Network Administration

25. Transition Problems • IPv6 is incompatible with IPv4 • Not every site is reachable with IPv6. • Every site will need some IPv4 addresses. • NAT is going to stay with us for some time. • Routers don’t support IPv6 in hardware. • Software routing is slower than hardware. • Home routers/cable modems don’t do IPv6 CIT 384: Network Administration

26. Key Topics IPv6 Addresses • 128-bit addresses: 64-bit network, 64-bit host • Global route aggregation • Site local and link local addresses • Stateless autoconfiguration with EUID-64 IPv4 to IPv6 Transition • Dual Stacks • Tunnels • NAT-PT CIT 384: Network Administration

27. References • Randy Bush, IPv6 Transition & Operational Reality, http://www.nanog.org/mtg-0710/presentations/Bush-v6-op-reality.pdf, 2007. • Cisco, Cisco Connection Documentation, http://www.cisco.com/univercd/home/home.htm • Cisco, Internetworking Basics, http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/introint.htm • Silvia Hagan, IPv6 Essentials, O’Reilly, 2002. • Charles M. Kozierok, The TCP/IP Guide, No Starch Press, 2005. • IPv4 Address Report, http://www.potaroo.net/tools/ipv4/index.html • Wendell Odom, CCNA Official Exam Certification Library, 3rd edition, Cisco Press, 2007. CIT 384: Network Administration