IPv6
Internet Protocol Version 6
Internet Protocol Version 6 (IPv6)
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IPv6 solutions to IPv4 disadvantages
IPv6 addressing
IPv6 header
DNS support for IPv6
Core protocols of IPv6
IPv6 Neighbor Discovery
Differences between IPv4 and IPv6
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Disadvantages of IPv4
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Limited address space
Flat routing infrastructure
Configuration
Security
Quality of service (QoS)
Mobility
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IPv6 Solutions to IPv4 Disadvantages
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Huge address space
Hierarchical routing infrastructure
Automatic configuration
Built-in security
Better support for QoS
Built-in mobility
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Larger Address Space
IPv4
• 32 bits or 4 bytes long
~
= 4,200,000,000 possible addressable nodes
IPv6
• 128 bits or 16 bytes: four times the bits of IPv4
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= 3.4 * 1038 possible addressable nodes
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= 340,282,366,920,938,463,374,607,432,768,211,456
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= 5 * 10 addresses per person
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IPv6 Adressing
2128
6.5 Billion
 52 Trillion Trillion
IPv6 addresses per person
6.5 Billion people on earth
52 Trillion Trillion
 523 Quadrillio n (523 thousand Trillion )
100 Billion
Typical braincell has
~100 Billion cells
(your count may vary)
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IPv6 addresses for every
human brain cell on the planet
2003-2004 - Information management
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Larger Address Space Enables Address Aggregation
• Aggregation of prefixes announced in the global
routing table
• Efficient and scalable routing
• Improved bandwidth and functionality for user traffic
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The IPv6 Address Space
• 128-bit address space
• 128 bits were chosen to allow multiple levels of
hierarchy and flexibility in designing hierarchical
addressing and routing
• Global unicast and anycast addresses are defined by a
global routing prefix, a subnet ID, and an interface ID
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IPv6 Address Representation
• x:x:x:x:x:x:x:x, where x is a 16-bit hexadecimal field
• Leading zeros in a field are optional:
– 2031:0:130F:0:0:9C0:876A:130B
• Successive fields of 0 can be represented as ::, but only
once per address.
Examples:
2031:0000:130F:0000:0000:09C0:876A:130B
2031:0:130f::9c0:876a:130b
FF01:0:0:0:0:0:0:1 >>> FF01::1
0:0:0:0:0:0:0:1 >>> ::1
0:0:0:0:0:0:0:0 >>> ::
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Compressing Zeros
• Some IPv6 addresses contain long sequences of zeros
• A single contiguous sequence of 16-bit blocks set to 0 can be
compressed to “::” (double-colon)
• Examples:
– FE80:0:0:0:2AA:FF:FE5F:47D1 becomes
FE80::2AA:FF:FE5F:47D1
– FEC0:0:0:41CD:2AA:FF:FE5F:47D1 becomes
FEC0::41CD:2AA:FF:FE5F:47D1
– FF02:0:0:0:0:0:0:1 (a multicast address) becomes FF02::1
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IPv6 Prefixes
• Prefix is the part of the address where the bits have
fixed values or are the bits of a route or subnet identifier
• IPv6 subnets or routes always uses address/prefix-length
notation
– CIDR notation
• Examples:
– 3FFE:FFFF:2A:41CD::/64 is a subnet identifier
– 3FFE:FFFF:2A::/48 is a route
– FF::/8 is an address range
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Types of IPv6 Addresses
• Unicast
– Address of a single interface
– One-to-one delivery to single interface
• Multicast
– Address of a set of interfaces
– One-to-many delivery to all interfaces in the set
• Anycast
– Address of a set of interfaces
– One-to-one-of-many delivery to a single interface in
the set that is closest
• No more broadcast addresses
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Unicast IPv6 Addresses
• Global addresses
– Used on IPv6 Internet
– Equivalent to IPv4 public
addresses
• Local-Use Addresses
– Site-local addresses
• Equivalent to IPv4 private
addresses
• Always begin with FEC0
– Link-local addresses
• Equivalent to APIPA
Global
addresses
• Always begin with FE80
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Site Local
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Link Local
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IPv6 Interface Identifiers
• Based on:
– Derived from the MAC address of the network
adapter to which the address is assigned
– Randomly generated to provide IPv4-equivalent
anonymity
– Assigned during a Point-to-Point Protocol (PPP)
connection
– Assigned during DHCP configuration
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IPv6 Interface identifier EUI-64
• Cisco uses the extended
universal identifier (EUI)-64
format to do stateless
autoconfiguration.
• This format expands the 48bit MAC address to 64 bits
by inserting “FFFE” into the
middle 16 bits.
• To make sure that the chosen
address is from a unique
Ethernet MAC address, the
universal/local (U/L bit) is
set to 1 for global scope (0
for local scope).
Mac address
48 bit
00 90 27 17 FC 0F
17 FC 0F 64 bit
00 90 27
FF FE
00 90 27 FF FE 17 FC 0F
000000U0
U=
1 = Unique
0 = Not Unique
02 90 27 FF FE 17 FC 0F
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IPv6 Header
IPv4 Header
Version IHL
Type of
Service
Identification
Time to Live
Protocol
IPv6 Header
Total Length
Flags
Fragment
Offset
Header Checksum
Version
Traffic
Class
Payload Length
Flow Label
Next
Header
Hop Limit
Source Address
Destination Address
Legend
Options
Padding
Source Address
Field’s Name Kept from IPv4 to IPv6
Fields Not Kept in IPv6
Name and Position Changed in IPv6
Destination Address
New Field in IPv6
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IPv6 Extension Header types
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Routing Header
Fragmentation Header
Hop-by-Hop Options Header
Destinations Options Header
Authentication Header
Encrypted Security Payload Header
Ethernet
header
IPv6
header
Routing
header
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Frag
header
Auth
header
ESP
header
TCP
header
Application
data
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DNS Support for IPv6
• AAAA resource records for name-to-address
resolutions
• PRT resource records in the IP6.ARPA reverse domain
for address-to-name resolutions
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Core Protocols of IPv6
• IPv6
– Replacement for IPv4
• ICMPv6
– Replacement for ICMP for IPv4
• Neighbor Discovery
– Replacement for ARP, Redirect, and Router
Discovery for IPv4
• Multicast Listener Discovery
– Replacement for IGMPv2 for IPv4
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IPv6 Neighbor Discovery
• Messages
– Neighbor Solicitation
– Neighbor Advertisement
– Router Solicitation
– Router Advertisement
– Redirect
• Processes
– Address resolution
– Duplicate address detection
– Router discovery
– Redirect
– Neighbor unreachability detection
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Stateless Autoconfiguration
• A router sends network information to all the nodes on the local
link.
• A host can autoconfigure itself by appending its IPv6 interface
identifier (64-bit format) to the local link prefix (64 bits).
• The result is a full 128-bit address that is usable and guaranteed
to be globally unique.
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A Standard Stateless Autoconfiguration
• Stage 1: The PC sends a router solicitation to request a
prefix for stateless autoconfiguration.
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A Standard Stateless Autoconfiguration (Cont.)
• Stage 2: The router replies with a router
advertisement.
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Differences Between IPv4 and IPv6
Feature
IPv4
IPv6
Address length
32 bits
128 bits
Header size
20-60 bytes
40 bytes
IPSec support
Optional
Required
QoS support
Some
Better
Fragmentation
Hosts and routers
Hosts only
Checksum in header
Yes
No
Options in header
Yes
No
Link-layer address resolution
ARP (broadcast)
Multicast Neighbor
Discovery Messages
Multicast membership
IGMP
Multicast Listener
Discovery (MLD)
Router Discovery
Optional
Required
Uses broadcasts?
Yes
No
Configuration
Manual, DHCP
Automatic, DHCP
DNS name queries
Uses A records
Uses AAAA
records
DNS
reverse
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Uses IN-ADDR.ARPA
Uses IP6.ARPA
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