Difference between revisions of "IPv6 Address"

Revision as of 12:14, 13 June 2011

IPv6 Address Types^[1]

Need To Know Address Allocations

Need To Know IPv6 Address Types Overview
Prefix	Example	Designation	IPv4 Equivalent
::/128		Unspecified	0.0.0.0
::1/128		Loopback	127.0.0.1
::ffff/96	::ffff:83.90.47.30	IPv4-Mapped	No Equivalent
fc00:/7	fdf8:f53b:82e4::53	Unique Local Address (ULA)	10/8, 172.16/12, 192.168/16
fe80::/10	fe80::221:86ff:fea0:ce84	Link-Local Address	169.254.0.0/16
2002::/16	2002:cb0a:3cdd:1::1	6to4	No Equivalent
2000::/3	2001:470:1f08:197d::2	Global Unicast	No single block.
ff00::/8	ff01::2	Multicast IPv6 Address	224.0.0.0/4

Nice To Know Address Allocations

Nice To Know IPv6 Address Types Overview
Prefix	Example	Designation	IPv4 Equivalent
2001:0000::/32	2001:0000:41ef::A819	Teredo	No Equivalent
2001:0002::/48	2001:0002:6c::430	Benchmarking	198.18.0.0/15
2001:0010::/28	2001:0010:10:240:ab::a	Orchid	No Equivalent
2001::db8/32	2001:db8:8:4::2	Documentation	Fx. 192.0.2.0/24

Configuring IPv6 addresses

Reference

↑ RIPE IPv6 Address Types

Link-Local

IPv6 Address Type:	Link-Local
Prefix:	fe80::/10
Local Routeable:	No
Global Routeable:	No
Global Unique:	No
Example:	FE80::21B:D4FF:FE0F:8CA2
IPv4 Equivalent:	169.254.0.0/16 Link-Local
Described in:	rfc4291

Explanation

These addresses are used on a single link or a non-routed common access network, such as an Ethernet LAN.

They do not need to be unique outside of that link.

Link-local addresses may appear as the source or destination of an IPv6 packet.

Routers must not forward IPv6 packets if the source or destination contains a link-local address.

IPv6 Address Types

IPv6 Link-Local Addresses

Link-Local Addresses are used by Nodes to communicate to other Nodes on the same Link. Link-Local addresses are not Routeable.

Windows 7 Link-Local Address Example

Format of Link-Local address

IPv6#<input>sh ipv6 int fa0/0</input>
FastEthernet0/0 is up, line protocol is up
  IPv6 is enabled, <notice>link-local address is FE80::21B:D4FF:FE0F:8CA2</notice>
  No Virtual link-local address(es):
  Description: Outside: Internet connection to ISP
  Global unicast address(es):
    2001:16D8:DD85:146::2, subnet is 2001:16D8:DD85:146::/64
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::D
    FF02::16
    FF02::1:FF00:2
    FF02::1:FF0F:8CA2
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ICMP unreachables are sent
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
  Hosts use stateless autoconfig for addresses.

Example why originating interface is important

Notice in the example below, we telnet to the Heimdal Router - the very same we're on - even I know that the Link-Local address FE80::218:18FF:FE7C:B440 is on a neighboring Router called Campus1.

<notice>Heimdal</notice>#<input>telnet FE80::218:18FF:FE7C:B440</input>
Trying FE80::218:18FF:FE7C:B440 ... Open
 !!!Netadmin Please upgrade the network security!!!
banner motd

User Access Verification

Password:
<notice>Heimdal</notice>><input>exit</input>

[Connection to FE80::218:18FF:FE7C:B440 closed by foreign host]

Link-Local addresses are local on a link. We need to tell on which interface the Link-Address are on. First we need to find the interface on which the address resides.

Heimdal#<input>show ipv6 neighbor | inc B440</input>
FE80::218:18FF:FE7C:B440                    0 0018.187c.b440  STALE <notice>Vl1</notice>

In the output in previous command, it's seen that the Link-Local address lives in Vlan1. Now we telnet from that source-interface - and Voila everything works as expected.

 
<notice>Heimdal</notice>#<input>telnet FE80::218:18FF:FE7C:B440 /source-interface vlan1</input>
Trying FE80::218:18FF:FE7C:B440 ... Open
 !!!Netadmin please upgrade Network Security!!!
banner motd

User Access Verification

Password:
<notice>Campus1</notice>>

Global Unicast

IPv6 Address Type:	Global Unicast
Prefix:	2000::/3
Local Routeable:	Yes
Global Routeable:	Yes
Global Unique:	Yes
Example:	2001:6D8:D85:4:210:11FF:FE34:540A
IPv4 Equivalent:	In IPv4 there are several Global Unicast block in Class A, B and C
Described in:	rfc4291
	IANA Unicast Assignments

Explanation

These are the Global IPv6 addresses used for Global Unicast communication. The ISP's Route these addresses - except those listed in IANA IPv6 Global Unicast Address Assignments

IPv6 Address Types

Multicast

IPv6 Address Type:	Multicast
Prefix:	ff00::/8
Local Routeable:	Yes and No
Global Routeable:	Yes and No
Global Unique:	Yes and No
Example:	FF0E::101
IPv4 Equivalent:	224.0.0.0/4
Described in:	rfc4291 section 2.7

Explanation

These addresses are used to identify multicast groups. They should only be used as destination addresses, never as source addresses.

IPv6 Address Types

Multicast Address Format

The IPv6 Multicast addresses contains two fields describing which kind of Multicast it is. Flag and Scope.

Flag Field

The flag field consists of four flags.


0	R	P	T

Flags
Flag	Explanation
T	T = 0 indicates a permanently-assigned well-known multicast address assigned by IANA. T = 1 indicates a non-permanently-assigned ("transient" or "dynamically" assigned) multicast address. See rfc4292
P	P = 0 indicates a multicast address that is not assigned based on the network prefix. P = 1 indicates a multicast address that is assigned based on the network prefix. See rfc3306
R	R = 0 indicates a multicast address that does not embed the address of the RP R = 1 indicates a multicast address that embed an RP (Rendezvous Point) See rfc3956
0	The high-order flag is reserved, and must be initialized to 0.

Scope Field

The Scope field is used to limit the Scope of the Multicast Group.

Multicast Address Scope Value in use
Value	Scope	Explanation
1	Interface-Local	Interface-Local scope spans only a single interface on a node and is useful only for loopback transmission of multicast.
2	Link Local	Link-Local multicast scope spans the same topological region as the corresponding unicast scope.
4	Admin Local	Admin-Local scope is the smallest scope that must be administratively configured, i.e., not automatically derived from physical connectivity or other, non-multicast-related configuration.
5	Site Local	Site-Local scope is intended to span a single site.
8	Organization Local	Organization-Local scope is intended to span multiple sites belonging to a single organization.
E	Global	Global span.

Variable Scope Multicast Addresses

The "meaning" of a Variable Scope or permanently-assigned multicast address is independent of the scope value. For example, if the "NTP servers group" is assigned a permanent multicast address with a group ID of FF0x::101 (hex), then

FF01::101 means all NTP servers on the same interface (i.e., the same node) as the sender.

FF02::101 means all NTP servers on the same link as the sender.

FF05::101 means all NTP servers in the same site as the sender.

FF0E::101 means all NTP servers in the Internet.

See IANA IPv6 Multicast Address Space Registry

Well Known Multicast examples


Address	Scope	Meaning	Description
FF01::1	Node	All Nodes	All nodes on the interface-local scope
FF01::2	Node	All Routers	All routers on the interface-local scope
FF02::1	Link Local	All Nodes	All nodes on the local-link scope
FF02::2	Link Local	All Routers	All routers on the link-local scope
FF05::2	Site	All Routers	All routers in a site scope

Pinging Multicast Addresses

In the first example below By pinging FF02::2 - All Routers on Local-Link - it's seen from the output below that there are two Routers responding

Campus1#<input>ping FF02::2 source vlan 1 repeat 1</input>
Output Interface: <input>vlan 1</input>
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to FF02::2, timeout is 2 seconds:
Packet sent with a source address of FE80::218:18FF:FE7C:B440

Reply to request 0 received from FE80::128C:CFFF:FE96:F76F, 0 ms
Reply to request 0 received from FE80::219:E7FF:FE51:8C0, 0 ms
Success rate is 100 percent (1/1), round-trip min/avg/max = 0/0/0 ms
2 multicast replies and 0 errors.

When pinging FF02::1 - All Nodes on Local-Link - it's seen that there are ten Nodes, including the two Routers from previous example. Using Local-Link address as source.

Campus1#<input>ping FF02::1 source vlan 1 repeat 1</input>
Output Interface: <input>vlan 1</input>
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to FF02::1, timeout is 2 seconds:
Packet sent with a source address of FE80::218:18FF:FE7C:B440

Reply to request 0 received from FE80::22CF:30FF:FEF0:C81A, 0 ms
Reply to request 0 received from FE80::22CF:30FF:FEF0:C880, 0 ms
Reply to request 0 received from FE80::250:56FF:FE8B:C, 0 ms
Reply to request 0 received from FE80::250:56FF:FE8B:3E, 0 ms
Reply to request 0 received from FE80::250:56FF:FE8B:2, 0 ms
Reply to request 0 received from FE80::250:56FF:FE8B:32, 0 ms
Reply to request 0 received from FE80::250:56FF:FE8B:36, 0 ms
Reply to request 0 received from FE80::207:E9FF:FE40:ABF, 0 ms
Reply to request 0 received from FE80::128C:CFFF:FE96:F76F, 0 ms
Reply to request 0 received from FE80::219:E7FF:FE51:8C0, 0 ms
Success rate is 100 percent (1/1), round-trip min/avg/max = 0/0/0 ms
10 multicast replies and 0 errors.

When pinging with Global Unicast as Source Address, some of the nodes respond with their Global Unicast Address. Appently

Campus1#<input>ping FF02::1 source 2001:16D8:DD85:139:218:18FF:FE7C:B441 repeat 1</input>
Output Interface: <input>vlan 139</input>
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to FF02::1, timeout is 2 seconds:
Packet sent with a source address of 2001:16D8:DD85:139:218:18FF:FE7C:B441

Reply to request 0 received from 2001:16D8:DD85:139:250:56FF:FE8B:A, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:20C:29FF:FE36:45B1, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:21B:21FF:FE52:917D, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:216:76FF:FE9F:FEF6, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:214:5EFF:FE67:614A, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:20C:29FF:FE4C:C0C, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:4A5B:39FF:FE5A:A7F7, 17 ms
Reply to request 0 received from 2001:16D8:DD85:139:9221:55FF:FEBC:BD97, 17 ms
Success rate is 100 percent (1/1), round-trip min/avg/max = 17/17/17 ms
8 multicast replies and 0 errors.

RFC's

rfc4291 "IP Version 6 Addressing Architecture" defines new flags in rfc3306 "Unicast-Prefix-based IPv6 Multicast Addresses" and rfc3956 "Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address"

Unique Local (ULA)

IPv6 Address Type:	Unique Local (ULA)
Prefix:	fc00::/7
Local Routeable:	Yes
Global Routeable:	No
Global Unique:	Preferable
Example:	fdf8:f53b:82e4::53
IPv4 Equivalent:	Private rfc1918 Adresses 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
Described in:	rfc4193

Explanation

These addresses are reserved for local use in home and enterprise environments and are not public address space.

These addresses might not be unique, and there is no formal address registration. Packets with these addresses in the source or destination fields are not intended to be routed on the public Internet but are intended to be routed within the enterprise or organisation.

See RFC 4193 for more details.

IPv6 Address Types

Unspecified

IPv6 Address Type:	Unspecified
Prefix:	::/128
Local Routeable:	No
Global Routeable:	No
Global Unique:	No

IPv4 Equivalent:	0.0.0.0
Described in:	rfc4291

Explanation

This address may only be used as a source address by an initialising host before it has learned its own address

Prefix ::/128 is the same as 0000:0000:0000:0000:0000:0000:0000:0000

IPv6 Address Types

Loopback

IPv6 Address Type:	Loopback
Prefix:	::1/128
Local Routeable:	No
Global Routeable:	No
Global Unique:	No

IPv4 Equivalent:	127.0.0.1
Described in:	rfc4291

Explanation

This address is used when a host talks to itself over IPv6. This often happens when one program sends data to another.

IPv6 Address Types

IPv4 Mapped

IPv6 Address Type:	IPv4 Mapped
Prefix:	::ffff/96
Local Routeable:	Yes
Global Routeable:	Yes
Global Unique:	Yes
Example:	::ffff:83.90.47.30
IPv4 Equivalent:	None
Described in:	rfc4291
	rfc4038 section 4.2

Explanation

These addresses are used to embed IPv4 addresses in an IPv6 address. One use for this is in a dual stack transition scenario where IPv4 addresses can be mapped into an IPv6 address.

See RFC 4038 for more details

IPv6 Address Types

IPv4-mapped IPv6 addresses are used in scenarios where IPv6 an IPv6-only application need to communicate with an IPv4 only application using IPv4 packets.

The IPv4-mapped address, 0:0:0:0:0:FFFF:w.x.y.z or ::FFFF:w.x.y.z, is used to represent an IPv4-only node to an IPv6 node. It is used only for internal representation. The IPv4-mapped address is never used as a source or destination address for an IPv6 packet. The IPv6 protocol does not support the use of IPv4-mapped addresses.^[1]

Dual-stack sockets always require IPv6 addresses. The ability to interact with an IPv4 address requires the use of the IPv4-mapped IPv6 address format. Any IPv4 addresses must be represented in the IPv4-mapped IPv6 address format which enables an IPv6 only application to communicate with an IPv4 node. The IPv4-mapped IPv6 address format allows the IPv4 address of an IPv4 node to be represented as an IPv6 address. The IPv4 address is encoded into the low-order 32 bits of the IPv6 address, and the high-order 96 bits hold the fixed prefix 0:0:0:0:0:FFFF. The IPv4-mapped IPv6 address format is specified in RFC 4291. For more information, see www.ietf.org/rfc/rfc4291.txt. The IN6ADDR_SETV4MAPPED macro in Mstcpip.h can be used to convert an IPv4 address to the required IPv4-mapped IPv6 address format.

If the underlying protocol is actually IPv4, then the IPv4 address is mapped into an IPv4-mapped IPv6 address format. That is the, family field in the SOCKADDR structure indicates AF_INET6, but an IPv4-mapped IPv6 address is encoded in the IPv6 address structure. For a dual-stack socket in listening mode, this means that any accepted IPv4 connections will return an IPv4-mapped IPv6 address. For a dual-stack socket that is connecting to an IPv4 destination, the SOCKADDR structure passed to connect must be an IPv4-mapped IPv6 address. Applications must take care to handle these IPv4-mapped IPv6 addresses appropriately and only use them with dual stack sockets. If an IP address is to be passed to a regular IPv4 socket, the address must be a regular IPv4 address not a IPv4-mapped IPv6 address.^[2]

Only seen working application using IPv4-mapped IPv6 addresses is Windows 7 ping!!!

<input>
C:\Users\Henrik thomsen><notice>ping ::ffff:192.168.139.50</notice>

Pinging 192.168.139.50 with 32 bytes of data:
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62

Ping statistics for 192.168.139.50:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms

</input>

or same as

<input>
C:\Users\Henrik thomsen><notice>ping ::ffff:c0a8:8b32</notice>

Pinging 192.168.139.50 with 32 bytes of data:
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62
Reply from 192.168.139.50: bytes=32 time<1ms TTL=62

Ping statistics for 192.168.139.50:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 0ms, Average = 0ms
</input>

6to4

IPv6 Address Type:	6to4
Prefix:	2002::/16
Local Routeable:	Yes
Global Routeable:	Yes
Global Unique:	Yes
Example:	2002:cb0a:3cdd:1::1
IPv4 Equivalent:	No equivalent
Described in:	rfc3056
	Cisco Routing IPv6 over IPv4
	version6.net on 6to4

Explanation

A 6to4 gateway adds its IPv4 address to this 2002::/16, creating a unique /48 prefix. As the IPv4 address of the gateway router is used to compose the IPv6 prefix, it is possible to reverse the process and identify the IPv4 address, which can then be looked up in the relevant RIR’s Whois database.

You can do this on the following webpage: http://www.potaroo.net/cgi-bin/ipv6addr

IPv6 Address Types

EUI-64 or Modified EUI-64 are often used as the lower 64 bit of a IPv6 Address.

EUI-64

EUI-64^[1] or Extended Unique Identifier is a 64 bit Global Identifier administered by IEEE^[2]

Examples of use

FireWire^[3] and in IPv6 as least significant 64 bits in Link-Local and Global Unicast if Stateless Autoconfiguration. (Except Systems that will choice a Random page fx. Windows 7)

EUI-48

EUI-48^[4] or Extended Unique Identifier is a 48 bit Global Identifier administered by IEEE^[5].

Examples of use

Ethernet MAC addresses is a example of EUI-48 usage. Other examples of technologies that use EUI-48 are Bluetooth and 802.11 Wireless Networks.

IPv6 Modifed EUI-64 Address

Understanding the MAC-Address

The MAC-Address is divided into two parts.

The first 24 bits identifies the manufacturer and are called the OUI
1. The OUI is administered by IEEE^[2]
The last 24 bits identifies Extension Identifier or NIC
1. The manufacturer can use this field as serial-number

The MAC-Address is Global Unique and has two flag in its first octet. (Byte)

bit 1: Unicast or Multicast
- The MAC 'broadcast' address FF:FF:FF:FF:FF:FF is really a Well-Known link-local Multicast address used by for example IPv4 ARP and DHCP.
bit 2: Globally or locally administered. When bit 2 is 0 the Global Unique IEEE^[2] identifier is used. When bit 2 is 1 it's a Local generated address.

Generating the Modified EUI-64

When generating a modified EUI-64 as the 64 lower bits of a IPv6 Address the hosts EUI-48 (MAC-Address) is expanded to 64 bits by inserting FF:FE between the OUI and the Extension Identifer or NIC and setting the Locally Administered Bit.

Example

A node with MAC-address 00:10:56:A7:16:D5 will generate 00:10:56:FF:FE:A7:16:D5 as EUI-64

References

[1] RIPE IPv6 Address Types

[2] ttp://technet.microsoft.com/en-us/library/cc759208(WS.10).aspx

[3] ttp://msdn.microsoft.com/en-us/library/windows/desktop/bb513665(v=vs.85).aspx

[4] ttp://standards.ieee.org/develop/regauth/tut/eui64.pdf

[IEEE-5] 2.0 ^2.1 ^2.2 http://www.ieee.org/index.html

[6] ttp://en.wikipedia.org/wiki/IEEE_1394_interface

[7] ttp://standards.ieee.org/develop/regauth/tut/eui48.pdf

[8] ttp://www.ieee.org/index.html

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