1 IPv6

2 Problem: 32-bit address space will be completely allocated by Solution: Design a new IP with a larger address space, called the IP version 6, IPv6 –Expanded Address Space: 128-bit addresses –IP Address Auto-configuration: Stateless (no servers) host IP Address Configuration (Plug-and-Play) –Security Capabilities: IPSec required –Better and hierarchical routing mechanisms: Current IPv4 routing infrastructure is a combination of flat and hierarchical routing. Leads to bigger routing tables at the backbone routers. –Improved Options Mechanism: Options are located between the IPv4 main header and transport headers. Most routers do not examine these option fields

3 IPv6 Addressing 128-bit addresses IPv4 – dotted decimal representation – IPv6 – 128-bit address divided along 16-bit boundaries, each 16-bit block converted to a 4 digit hexadecimal number separated by colons – –21DA:00D3:0000:2F3B:02AA:00FF:FE28:9C5A –Can be simplified by removing leading 0’s within each 16-bit block –21DA:D3:0:2F3B:02AA:FF:FE28:9C5A

4 IPv6 Addressing – Compressing 0’s Some type of addresses contain long sequences of 0s. To further simplify the representation of IPv6 addresses, a contiguous sequence of 16-bit blocks set to 0 in the colon format can be compressed to “::”, known as double colon –Example1: FE80:0:0:0:2AA:FF:FE9A:4CA2 FE80::2AA:FF:FE9A:4CA2 –Example2: FF02:0:0:0:0:0:0:2 FF02::2

5 Types of IPv6 Addresses 3 types of addresses –Unicast Addresses Identifies a single interface within the whole IPv6 Network. A packet sent to a unicast address is delivered to a single interface –Multicast Addresses Identifies multiple interfaces. A packet sent to a multicast address is delivered to ALL multicast interfaces. –Anycast Addresses Identifies multiple interfaces. A packet sent to a anycast address is delivered to ANY one of the interfaces. Typically the closest interface

6 Unicast IPv6 Addresses Global unicast addresses Link-Local addresses Site-Local addresses -- deprecated Special addresses

7 Global Unicast IPv6 Addresses

8 Link-Local Unicast IPv6 Addresses Always start with FE80::/64 Equivalent to IPv /16 address range An IPv6 router never forwards link-local traffic beyond the link

9 Site-Local Unicast IPv6 Addresses Always start with FEC0::/10 Equivalent to IPv4 10/8, /12, /16 address ranges Scope of a site-local address is the site. Deprecated – Not to be used any longer!

10 Special Unicast IPv6 Addresses 0:0:0:0:0:0:0:0 or :: –Indicates the lack of an address –Corresponds to IPv :0:0:0:0:0:0:1 or ::1 –Loopback interface address –Corresponds to IPv4 loopback IP address

11 Interface ID Generation

12 Interface ID Generation - Example MAC: 00-AA-00-3F-2A-1C EUI-64: 00-AA-00-FF-FE-3F-2A-1C Intf ID: 02-AA-00-FF-FE-3F-2A-1C Colon Hexadecimal Notation: 2AA:FF:FE3F:2A1C Link-Local Address: FE80::2AA:FF:FE3F:2A1C Notice that the above algorithm generates the same UID from the same MAC To provide anonymity, RFC 3041 suggests an alternative that generates IDs that change over time

13 IPv6 Subnets – Example INTERNET 2000::1:InterfaceID 2000::2:InterfaceID 2000::3:InterfaceID Similar to IPv4, an IPv6 subnet prefix (subnetID) is assigned to a single link Multiple subnetIDs may be assigned to the same link 3 IPv6 Subnets in above network –2000::1/64, 2000::2/64, 2000::3/64 No need for netmask

14 IPv6 Datagram Format Ver: 6 Priority: identify priority among datagrams in flow Flow Label: identify datagrams in same “flow.” Next header: identify upper layer protocol for data; or the offset of the next options header 128-bit source & destination addresses Fixed-length 40 byte header

15 Other Changes from IPv4 Checksum: removed entirely to reduce processing time at each hop Options: allowed, but outside of header, indicated by “Next Header” field ICMPv6: new version of ICMP –additional message types, e.g. “Packet Too Big” –multicast group management functions

16 IPv6 Forwarding Similar to IPv4 Forwarding If the destination is on the same IPv6 Subnet –Deliver the packet directly using LL –Otherwise, deliver the packet to the default router IPv6 Address  MAC Resolution? –No ARP in IPv6 –MAC resolution performed by ICMP Neighbor solicitation messages sent to multicast solicited node address Disturbs less nodes on the network

17 IPv6 Fragmentation & Reassembly large IP datagram divided (“fragmented”) ONLY at the source –one datagram becomes several datagrams –“reassembled” ONLY at final destination –Optional Fragmentation header is used if the packet is fragmented. What if the packet needs to be fragmented within the network? –Router drops the packet and sends a “PACKET TOO BIG” ICMP response back to the sender. fragmentation: in: one large datagram out: 3 smaller datagrams reassembly

18 Host IPv6 Address Configuration HIGH-LEVEL DESCRIPTION 1.Always configure a link-local address 2.Listen for router advertisements 1.If router advertisement indicates that a stateful address configuration is to be used, then use DHCP to get another address 2.If router advertisement indicates that a stateless address configuration is to be used, then take the routing prefix from the router advertisement and configure an address