IPv6
Internet Protocol, Version 6
Yen-Cheng Chen
NCNU
ycchen@ncnu.edu.tw
IP v6 - Version Number
IP
IP
IP
IP


v 1-3 defined and replaced
v4 - current version
v5 - streams protocol
v6 - replacement for IP v4
During development it was called IPng
Next Generation
IPv6 RFCs
1752 - Recommendations for the IP Next
Generation Protocol
2460 – IPv6 specification
2373 - addressing structure
others (find them)
http://playground.sun.com/pub/ipng/html/specs/specifications.html
Why Change IP?
Address space exhaustion
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



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


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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
Without Extension Headers
IPv6 Header
Next Header=
TCP
TCP Header
Data
With Extension Headers
IPv6 Header
Next Header=
Routing
Routing Header
Next Header=
TCP
IPv6 Header
Next Header=
Routing
Routing Header Fragment Header
Next Header=
Next Header=
TCP Header
Fragment
TCP
TCP Header
Data
Data
Hop-by-Hop Options
NH
HEL
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
Type-Length-Value (TLV)
Option Type



Option Data Length
Option Type (8-bit)
Option Data Length (8-bit)
Option Data (variable)
Option Data
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 Header
Hdr Ext Len
Routing Type Segments Left
Type-Specific Data
Next Header
Hdr Ext Len
RT = 0
Reserved
Address[1]
Address[2]
..
.
Address[n]
Segments Left
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
NH
HEL
Options
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:BA98:7654:3210
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
Allocation
Prefix
Fraction
Reserved
Unassigned
Reserved for NSAP Allocation
Reserved for IPX Allocation
Unassigned
Unassigned
Unassigned
Aggregatable Global Unicast Addresses
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Unassigned
Link-Local Unicast Addresses
Site-Local Unicast Addresses
Multicast Addresses
0000 0000
0000 0001
0000 001
0000 010
0000 011
0000 1
0001
001
010
011
100
101
110
1110
1111 0
1111 10
1111 110
1111 1110 0
1111 1110 10
1111 1110 11
1111 1111
1/256
1/256
1/128
1/128
1/128
1/32
1/16
1/8
1/8
1/8
1/8
1/8
1/8
1/16
1/32
1/64
1/128
1/512
1/1024
1/1024
1/256
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
128 bits
node address
n bits
subnet prefix
128-n bits
interface ID
IPv6 Addresses with Embedded IPv4
Addresses
IPv4-compatible IPv6 address
80 bits
16
0000……………………0000 0000
32 bits
IPv4 Addresses
IPv4-mapped IPv6 address
80 bits
16
32 bits
0000……………………0000
FFFF
IPv4 Addresses
Aggregatable Global Unicast Addresses
FP
TLA ID
RES
NLA ID
SLA ID
INTERFACE ID
Format Prefix (001)
Top-Level Aggregation Identifier
Reserved for future use
Next-Level Aggregation Identifier
Site-Level Aggregation Identifier
Interface Identifier
Local-Use IPv6 Unicast Addresses
Link-Local Unicast Addresses
10 bits
54 bits
64 bits
0
Interface ID
1111111010
Site-Local Unicast Addresses
10 bits
1111111011
FE80::x:x:x:x
FEC0::s:x:x:x:x
38 bits
16 bits
64 bits
0
Subnet ID
Interface ID
Multicast Addresses
8 bits
11111111
4 bits
4 bits
112 bits
Flags
Scope
Group ID
0000 : well known
0001 : transient
Multicasting
Addresses that refer to group of hosts on
one or more networks
Uses

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Multimedia “broadcast”
Teleconferencing
Database
Distributed computing
Real time workgroups