IPv6 Internet Protocol, Version 6 Yen-Cheng Chen NCNU

IP v6 - Version Number IP v 1-3 defined and replaced IP v4 - current version IP v5 - streams protocol IP v6 - replacement for IP v4 During development it was called IPng Next Generation

IPv6 RFCs Recommendations for the IP Next Generation Protocol 2460 – IPv6 specification addressing structure others (find them)

Why Change IP? Address space exhaustion Two level addressing (network and host) wastes space Network addresses used even if not connected to Internet Growth of networks and the Internet Extended use of TCP/IP Single address per host Requirements for new types of service

Changes from IPv4 to IPv6 Expanded Addressing Capabilities Header Format Simplification Improved Support for Options Flow Labeling Capabilities Authentication and Privacy Capabilities

IPv6 Enhancements Expanded address space 128 bit Improved option mechanism Separate optional headers between IPv6 header and transport layer header Most are not examined by intermediate routes  Improved speed and simplified router processing  Easier to extend options Address autoconfiguration Dynamic assignment of addresses

IPv6 Enhancements (2) Increased addressing flexibility Anycast - delivered to one of a set of nodes Improved scalability of multicast addresses Support for resource allocation Replaces type of service Labeling of packets to particular traffic flow Allows special handling e.g. real time video

IP v6 Header

IP v6 Header Fields (1) Version 6 Traffic Class Classes or priorities of packet Still under development See RFC 2460 Flow Label Used by hosts requesting special handling Payload length Includes all extension headers plus user data

IP v6 Header Fields (2) Next Header Identifies type of header  Extension or next layer up Source Address Destination address

IPv6 Extension Headers Hop-by-Hop options header Require processing at each router Routing header Similar to IPv4 source routing Fragment header Destination options header For destination node Authentication header (RFC 2402) Encrypted security payload (RFC 2406)

IPv6 Extension Headers IPv6 Header Next Header=Routing TCP Header Routing Header Next Header=TCP IPv6 Header Next Header=Routing TCP Header Routing Header Next Header=Fragment Fragment Header Next Header=TCP IPv6 Header Next Header=TCP Data TCP Header Data Without Extension Headers With Extension Headers

Hop-by-Hop Options Next header (8-bit) Header extension length (8-bit) Options Jumbo payload (RFC 2675)  Over 2 16 = 65,535 octets Router alert (RFC 2711)  Tells the router that the contents of this packet is of interest to the router  Provides support for RSVP Options NHHEL

Options Type-Length-Value (TLV) Option Type (8-bit) Option Data Length (8-bit) Option Data (variable) Option Data Length Option Data Option Type

Routing Header List of one or more intermediate nodes to be visited Next Header Header extension length Routing type Segments left i.e. number of nodes still to be visited Next HeaderHdr Ext LenRouting Type Segments Left Type-Specific Data

Next Header Hdr Ext Len RT = 0 Segments Left Reserved Address[1] Address[2] Address[n]......

Fragmentation Header Fragmentation only allowed at source No fragmentation at intermediate routers Node must perform path discovery to find smallest MTU of intermediate networks Source fragments to match MTU Otherwise limit to 1280 octets

Fragmentation Header Fields Next Header Reserved Fragmentation offset Reserved More flag Identification

Destination Options Same format as Hop-by-Hop options header Options NHHEL

IPv6 Addresses 128 bits long Assigned to interface Single interface may have multiple unicast addresses Three types of address

Types of address Unicast Single interface Anycast Set of interfaces (typically different nodes) Delivered to any one interface the “nearest” Multicast Set of interfaces Delivered to all interfaces identified

Text Representation of IPv6 Addresses x:x:x:x:x:x:x:x hexadecimal values of the eight 16-bit pieces of the address. FEDC:BA98:7654:3210:FEDC:BA98:7654: :0:0:0:8:800:200C:417A

IPv6 Address Representation (2) The use of "::" indicates multiple groups of 16-bits of zeros. Unicast address 1080:0:0:0:8:800:200C:417A 1080::8:800:200C:417A Multicast address FF01:0:0:0:0:0:0:101  FF01::101 Loopback address 0:0:0:0:0:0:0:1  ::1 unspecified addresses 0:0:0:0:0:0:0:0  ::

IPv6 Address Representation (3) IPv4 and IPv6 mixed address x:x:x:x:x:x:d.d.d.d x: IPv6, d: IPv4 Eg.  0:0:0:0:0:FFFF:  ::  ::FFFF:

Reserved /256 Reserved / Unassigned /256 Reserved for NSAP Allocation /128 Reserved for NSAP Allocation /128 Reserved for IPX Allocation /128 Reserved for IPX Allocation / Unassigned / Unassigned / /16 Unassigned /16 Aggregatable Global Unicast Addresses 001 1/8 Aggregatable Global Unicast Addresses 001 1/8 010 Unassigned 010 1/8 011 Unassigned 011 1/8 100 Unassigned 100 1/8 101 Unassigned 101 1/8 110 Unassigned 110 1/ Unassigned / Unassigned / Unassigned / Unassigned / /512 Unassigned /512 Link-Local Unicast Addresses /1024 Link-Local Unicast Addresses /1024 Site-Local Unicast Addresses /1024 Site-Local Unicast Addresses /1024 Multicast Addresses /256 Multicast Addresses /256 Allocation Prefix Fraction

Unicast Addresses global aggregatable global unicast address NSAP address IPX hierarchical address site-local address link-local address IPv4-capable host address

IPv6 Unicast Addresses node address subnet prefix interface ID 128 bits n bits 128-n bits

IPv6 Addresses with Embedded IPv4 Addresses IPv4-compatible IPv6 address IPv4-mapped IPv6 address 0000 …………………… bits 16 IPv4 Addresses 32 bits 0000 …………………… 0000 FFFF 80 bits 16 IPv4 Addresses 32 bits

Aggregatable Global Unicast Addresses FP Format Prefix (001) TLA ID Top-Level Aggregation Identifier RES Reserved for future use NLA ID Next-Level Aggregation Identifier SLA ID Site-Level Aggregation Identifier INTERFACE ID Interface Identifier

Local-Use IPv6 Unicast Addresses Link-Local Unicast Addresses Site-Local Unicast Addresses Interface ID 10 bits 54 bits 64 bits Interface ID 10 bits 38 bits 64 bits Subnet ID 16 bits FE80::x:x:x:x FEC0::s:x:x:x:x

Multicast Addresses Group ID 8 bits 4 bits 112 bits FlagsScope 4 bits 0000 : well known 0001 : transient

Multicasting Addresses that refer to group of hosts on one or more networks Uses Multimedia “broadcast” Teleconferencing Database Distributed computing Real time workgroups