IPv6Internet Protocol, Version 6

Yen-Cheng ChenNCNUycchen@ncnu.edu.tw

IP v6 - Version Number

IP v 1-3 defined and replacedIP v4 - current versionIP v5 - streams protocolIP v6 - replacement for IP v4 During development it was called IPng Next Generation

IPv6 RFCs

1752 - Recommendations for the IP Next Generation Protocol2460 – IPv6 specification2373 - addressing structureothers (find them)

http://playground.sun.com/pub/ipng/html/specs/specifications.html

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 CapabilitiesHeader 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 AddressDestination address

IPv6 Extension Headers

Hop-by-Hop options header Require processing at each router

Routing header Similar to IPv4 source routing

Fragment headerDestination options header For destination node

Authentication header (RFC 2402)Encrypted security payload (RFC 2406)

IPv6 Extension Headers

IPv6 HeaderNext Header=RoutingRouting

TCP HeaderRouting HeaderNext Header=TCPTCP

IPv6 HeaderNext Header=RoutingRouting

TCP HeaderRouting HeaderNext Header=FragmentFragment

Fragment HeaderNext Header=TCPTCP

IPv6 HeaderNext Header=TCPTCP

DataTCP Header

Data

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 216 = 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

NH HEL

Options

Type-Length-Value (TLV)

Option Type (8-bit) Option Data Length (8-bit) Option Data (variable)

Option Data Length Option DataOption Type

Routing HeaderList of one or more intermediate nodes to be visitedNext HeaderHeader extension lengthRouting typeSegments left i.e. number of nodes still to be visited

Next Header Hdr Ext Len Routing 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 sourceNo fragmentation at intermediate routersNode must perform path discovery to find smallest MTU of intermediate networksSource fragments to match MTUOtherwise limit to 1280 octets

Fragmentation Header Fields

Next HeaderReservedFragmentation offsetReservedMore flagIdentification

Destination Options

Same format as Hop-by-Hop options header

Options

NH HEL

IPv6 Addresses

128 bits longAssigned to interfaceSingle interface may have multiple unicast addressesThree 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:xhexadecimal values of the eight 16-bit pieces of the address. FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 1080:0:0:0:8:800:200C: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:129.144.52.38 ::13.1.68.3 ::FFFF:129.144.52.38

Reserved Reserved 0000 0000 0000 0000 1/2561/256 Unassigned 0000 00010000 0001 1/256 Reserved for NSAP Allocation Reserved for NSAP Allocation 0000 001 0000 001 1/1281/128 Reserved for IPX Allocation Reserved for IPX Allocation 0000 010 0000 010 1/1281/128 Unassigned 0000 0110000 011 1/128 Unassigned 0000 10000 1 1/32 Unassigned 0001 0001 1/161/16 Aggregatable Global Unicast Addresses Aggregatable Global Unicast Addresses 001 001

1/81/8 Unassigned 010010 1/8 Unassigned 011011 1/8 Unassigned 100100 1/8 Unassigned 101 101 1/8 Unassigned 110110 1/8 Unassigned 1110 1110 1/16 Unassigned 1111 01111 0 1/32 Unassigned 1111 101111 10 1/64 Unassigned 1111 1101111 110 1/128 Unassigned 1111 1110 0 1111 1110 0 1/5121/512 Link-Local Unicast Addresses Link-Local Unicast Addresses 1111 1110 10 1111 1110 10 1/10241/1024 Site-Local Unicast Addresses Site-Local Unicast Addresses 1111 1110 11 1111 1110 11 1/10241/1024 Multicast Addresses Multicast Addresses 1111 1111 1111 1111 1/2561/256

Allocation Prefix Fraction

Unicast Addresses

global aggregatable global unicast addressNSAP addressIPX hierarchical addresssite-local addresslink-local addressIPv4-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……………………0000 0000

80 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

1111111010 0 Interface ID

10 bits 54 bits 64 bits

1111111011 0 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

11111111 Group ID

8 bits 4 bits 112 bits

Flags Scope

4 bits

0000 : well known0001 : transient

Multicasting

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