IPv 6 1 IPv 6 Problem 32 bit

IPv 6 1

IPv 6 • Problem: 32 -bit address space will be completely allocated by 2008. • Solution: Design a new IP with a larger address space, called the IP version 6, IPv 6 – 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 IPv 4 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 IPv 4 main header and transport headers. Most routers do not examine these option fields 2

IPv 6 Addressing • 128 -bit addresses • IPv 4 – dotted decimal representation – 223. 1. 1. 1 • IPv 6 – 128 -bit address divided along 16 -bit boundaries, each 16 -bit block converted to a 4 digit hexadecimal number separated by colons – 0010000111011010 000011010011 00000000 0010111100111011 – 21 DA: 00 D 3: 0000: 2 F 3 B: 02 AA: 00 FF: FE 28: 9 C 5 A – Can be simplified by removing leading 0’s within each 16 -bit block – 21 DA: D 3: 0: 2 F 3 B: 02 AA: FF: FE 28: 9 C 5 A 3

IPv 6 Addressing – Compressing 0’s • Some type of addresses contain long sequences of 0 s. To further simplify the representation of IPv 6 addresses, a contiguous sequence of 16 -bit blocks set to 0 in the colon format can be compressed to “: : ”, known as double colon – Example 1: • FE 80: 0: 2 AA: FF: FE 9 A: 4 CA 2 • FE 80: : 2 AA: FF: FE 9 A: 4 CA 2 – Example 2: • FF 02: 0: 0: 0: 2 • FF 02: : 2 4

Types of IPv 6 Addresses • 3 types of addresses – Unicast Addresses • Identifies a single interface within the whole IPv 6 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 5

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

Global Unicast IPv 6 Addresses 7

Link-Local Unicast IPv 6 Addresses • Always start with FE 80: : /64 • Equivalent to IPv 4 169. 254/16 address range • An IPv 6 router never forwards link-local traffic beyond the link 8

Site-Local Unicast IPv 6 Addresses • Always start with FEC 0: : /10 • Equivalent to IPv 4 10/8, 172. 16/12, 192. 168/16 address ranges • Scope of a site-local address is the site. • Deprecated – Not to be used any longer! 9

Special Unicast IPv 6 Addresses • 0: 0: 0 or : : – Indicates the lack of an address – Corresponds to IPv 4 0. 0 • 0: 0: 1 or : : 1 – Loopback interface address – Corresponds to IPv 4 loopback IP address 127. 0. 0. 1 10

Interface ID Generation 11

Interface ID Generation - Example • MAC: • EUI-64: • Intf ID: 00 -AA-00 -3 F-2 A-1 C 00 -AA-00 -FF-FE-3 F-2 A-1 C 02 -AA-00 -FF-FE-3 F-2 A-1 C • Colon Hexadecimal Notation: 2 AA: FF: FE 3 F: 2 A 1 C • Link-Local Address: FE 80: : 2 AA: FF: FE 3 F: 2 A 1 C • 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 12

IPv 6 Subnets – Example INTERNET 2000: : 2: Interface. ID 2000: : 1: Interface. ID 2000: : 2: Interface. ID 2000: : 3: Interface. ID • Similar to IPv 4, an IPv 6 subnet prefix (subnet. ID) is assigned to a single link • Multiple subnet. IDs may be assigned to the same link • 3 IPv 6 Subnets in above network – 2000: : 1/64, 2000: : 2/64, 2000: : 3/64 • No need for netmask 13

• • IPv 6 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 14

Other Changes from IPv 4 • Checksum: removed entirely to reduce processing time at each hop • Options: allowed, but outside of header, indicated by “Next Header” field • ICMPv 6: new version of ICMP – additional message types, e. g. “Packet Too Big” – multicast group management functions 15

IPv 6 Forwarding • Similar to IPv 4 Forwarding • If the destination is on the same IPv 6 Subnet – Deliver the packet directly using LL – Otherwise, deliver the packet to the default router • IPv 6 Address MAC Resolution? – No ARP in IPv 6 – MAC resolution performed by ICMP Neighbor solicitation messages sent to multicast solicited node address • Disturbs less nodes on the network 16

IPv 6 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. fragmentation: in: one large datagram out: 3 smaller datagrams reassembly • 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. 17

Host IPv 6 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 18