- Ipv6 Link Local Address Format
- Implementing IPv6 Addressing And Basic Connectivity
- Ipv6 Link Local Address Calculator
- Link Local Ipv6 Address Example
- Ipv6 Link Local Address Calculator Online
For IPv6 link-local addresses (fe80::/10 prefix), the sin6scopeid member in the sockaddrin6 structure is the interface number. For IPv6 site-local addresses (fec0::/10 prefix), the sin6scopeid member in the sockaddrin6 structure is a site identifier. An example of a link-local IPv6 address on interface #5 is the following. We can activate the EUI-64 process, but by default Windows uses a random value for generating IPv6 Link-Local Addresses. EUI-64 (64-Bit Extended Unique Identifier) Let's take a look at a Cisco router. The IPv6 address of this router is calculated from the MAC address of the interface. Experiment using the IPv6 Address Calculator. IPv6 Link Local Multicast Address Format. As if this stuff was not already complicated RFC 4489 introduced the concept of a link-local (or link scoped) multicast format for situations where all configuration is stateless. Theoretically, routers (and other equipment) servicing a local (non-global.
IPv6 Subnet Calculator Classless Inter-Domain Routing (CIDR) CIDR is a packet routing system used to allocate IP address blocks. An IP address can be considered to have a network address and a host identifier. Routers must not forward any packets with Link-Local source or destination addresses to other links. IPv6 link-local addresses are equivalent to the IPv4 link-local addresses 169.254.0.0/16 also know as IPv4 Automatic Private IP Addressing (APIPA) addresses. Link-Local addresses have the following format.
IPv6 link-local and site-local addresses are called scoped addresses. The Windows Sockets (Winsock) API supports the sin6_scope_id member in the sockaddr_in6 structure for use with scoped addresses. For IPv6 link-local addresses (fe80::/10 prefix), the sin6_scope_id member in the sockaddr_in6 structure is the interface number. For IPv6 site-local addresses (fec0::/10 prefix), the sin6_scope_id member in the sockaddr_in6 structure is a site identifier.
An example of a link-local IPv6 address on interface #5 is the following:
The following command is available on Windows XP with Service Pack 1 (SP1) and later to query and configure IPv6 on a local computer:
Configuration changes made using the Netsh.exe commands are permanent and are not lost when the computer or the IPv6 protocol is restarted.
Prior to Windows XP with Service Pack 1 (SP1), IPv6 configuration and management used several older command-line tools (Net.exe, Ipv6.exe, and Ipsec6.exe) to configure and manage IPv6. Using these older tools, the IPv6 changes are not permanent and are lost when the computer or the IPv6 protocol was restarted. These older command-line tools are only supported on Windows XP.
On Windows XP with SP1, the following command will display the list of IPv6 interfaces on a local computer including the interface index, the interface name, and various other interface properties.
netsh interface ipv6 show interface
On Windows XP with SP1, the following command will change the site identifier associated with an interface index.
netsh interface ipv6 set interface siteid=value
On Windows XP, the following older command will also change the site identifier associated with a site-local address to 3.
Ipv6 Link Local Address Format
ipv6 rtu fec0::/10 3
If you are sending or connecting to a scoped address, then the sin6_scope_id member in the sockaddr_in6 structure can be left unspecified (zero) which represents an ambiguous scoped address. For example, the following link-local address is ambiguous:
If you are binding to a scoped address, then the sin6_scope_id member in the sockaddr_in6 structure must contain a nonzero value that specifies a valid interface number for a link-local address or a site identifier for a site-local address.
Ambiguous Scoped Addresses
If you are sending or connecting to a scoped address and have not specified the sin6_scope_id member in the sockaddr_in6 structure, then the scoped address is ambiguous. To resolve this, the IPv6 protocol first determines whether you have bound the socket to a source address. If so, the bound source address resolves the ambiguity by supplying an interface number or site identifier.
If you are sending or connecting to a scoped address and have neither specified the sin6_scope_id member nor bound a source address, then the IPv6 protocol checks the routing table. For example, the following command will display the IPv6 routing table on a local computer:
netsh interface ipv6 show route
This indicates that link-local addresses are treated as on-link to interface #13 and #14 by default.
Toast titanium update. Ambiguity arises when a local computer has multiple network adapters. For example, the netsh command above indicates there are two network interfaces (Local Area Connection and Wireless Network Connection). When an application specifies a destination link-local address (fe80::10, for example) without a scope ID, it is not clear which adapter to use to send the packet. Only a link-local unicast (fe80::/64) or a link-scope multicast (ff00::/8) IPv6 destination address can suffer from not having a scope ID when sending a packet.
Neighbor Discovery
If you have not specified the sin6_scope_id member in the sockaddr_in6 structure, have not bound a source address, and have not specified a route for link-local addresses, then the IPv6 protocol will try Neighbor Discovery to resolve the destination link-local address. For a given packet being sent, one interface is tried. This first interface that is tried is considered the most preferred interface. If Neighbor Discovery fails to resolve the link-local address on an interface, the packet to be sent is dropped and the system remembers that the destination link-local address is not reachable over that interface. On the next packet to be sent under all of the same conditions, a different interface is tried for Neighbor Discovery. This process continues through each of the interfaces on a local computer for each new packet until Neighbor Discovery responds for the destination link-local address or all of the possible interfaces have been tried and failed. Each time an attempt to resolve the neighbor fails, one interface is eliminated for that neighbor.
If the destination link-local address resolves, then that interface is used to send the current packet. This interface is also used for any subsequent ambiguously-scoped packets that are sent to the same link-local destination address. Hello neighbor unblocked 77.
If Neighbor Discovery fails to resolve the destination link-local address on all interfaces, the system then tries to send the packet on the most preferred interface (the first interface tried). The network stack keeps trying to resolve the destination link-local address on the most preferred interface. After a period of time after Neighbor Discovery has failed on all interfaces, the network stack will restart the process again and try to resolve the destination link-local address on all of the interfaces. External memory storage 1tb. Currently, this time interval when Neighbor Discovery is again tried on all interfaces is 60 seconds. However, this time interval may change on versions of Windows and should not be assumed by an application.
Note
If an application binds the same link-local address to a different interface after Neighbor Discovery has resolved the link-local address, that will not override the interface with the link-local destination address returned by Neighbor Discovery.
For more information on Neighbor Discovery for IP version 6, see RFC4861 published by the IETF.
Related topics
Warning: you need Javascript to use this form! Please activate it.
The forms below give you the ability to calculate various properties of IP addresses and the texts around them give you some hints about how to use them.
IPv4 Addresses
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| Misc Address | / |
| Network Mask | |
| Network Base | 192.168.0.0 |
| First usable Address | 192.168.0.1 |
| Last usable Address | 192.168.0.253 |
| Default Gateway | 192.168.0.254 |
| Broadcast Address | 192.168.0.255 |
Implementing IPv6 Addressing And Basic Connectivity
The following special addresses and networks exist in IPv4:| 0.0.0.0 | the 'ANY' address that is used by programs to speak to all network interfaces, it is never used directly. The whole network 0.*.*.* is reserved for special purposes (like DHCP). |
| 10.*.*.* 172.16.*.* - 172.31.*.* 192.168.*.* | are private addresses - you can use them freely within your own LAN. They will not be routed in the Internet. |
| 127.0.0.1 | is the localhost address, used by each host to talk to itself, there is always a special loopback interface preconfigured with this address, you never assign it to a real network device. The entire 127.*.*.* network is reserved for (host-)local networking. |
| 169.254.*.* | Link-Local addresses. These are automatically generated by some operating systems and (e.g. MacOS and Linux with Avahi installed) and are only usable for local communication in the LAN segment. |
| 198.18.*.* - 198.19.*.* | Network benchmark tests, this should never be used in production networks. |
| 198.51.100.* 203.0.113.* | TEST-NET-2, Documentation and examples TEST-NET-3, Documentation and examples |
| 224.*.*.* | Multicasts (former Class D network) - Warning: the data shown when you click this network is not completely accurate - e.g. there is no default gateway or broadcast for multicasting |
| 240.0.0.0/4 | Reserved (former Class E network) |
| 255.255.255.255 | Link Broadcast - this is sent to all hosts on the same network link, but does not cross routers |
IPv4 to IPv6 Transitional
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Ipv6 Link Local Address Calculator
IPv4 in IPv6 Addresses
In some configurations IPv4 addresses can be written or used in IPv6 notation or they become part of an IPv6 address. This form allows you to convert from IPv4 to IPv6 and back. Depending on your application you may have to shift the IPv6 segments.| IPv4 Address: | Please use dotted decimal notation. |
| IPv6 Address: | Please use hexadecimal notation with the relevant 32 bits to the far right. |
6to4 and 6RD Network Prefix
6to4 and 6rd are transitional mechanisms that will be used until native IPv6 is universally available. With both mechanisms you can assign an IPv6 prefix to an entire network based on the IPv4 address of the gateway. Both use the 6in4 encapsulation to transport IPv6 packets inside IPv4 packets between the border gateway of the local network and the gateway servers outside.6to4 is a public service, everybody can configure a gateway to use it - no subscription is necessary, since gateways will always know where to route responses based on the prefix. All 6to4 prefixes are in the 2002::/16 network and are /48 bits long (16bits for 2002::/16 and 32bits from the IPv4 address of the gateway). Unfortunately this service has become quite unreliable since public gateway servers seem to be unable to scale with the demand for prefixes.
6rd is the provider internal equivalent of 6to4. The provider establishes a gateway (or cluster of gateways) in its internal network and customer gateways are configured to use this gateway. The provider side prefix can be considerable longer than with 6to4 (/32 is normal), but it is also quite common to use only some bits of the IPv4 address - normally IPv4 addresses for customers are either assigned from a limited pool of public addresses (a /16 being the norm) or from one of the 'private' pools (e.g. 10.0.0.0/8), so the leftmost bits of every customer IP will be identical and can be ignored. For this mechanism to work you have to be a subscriber of an ISP that provides this mechanism to its customers. The values that go into this calculation may or may not have some resemblance to what you can find out using the whois service, but the provider is free to use sub-nets, so you will need information directly from the provider.
| Provider prefix IPv6: | / Use 2002::/16 for 6to4 and whatever you ISP gave you for 6rd |
| Customer IPv4: | IP: using bits; use your public IPv4 address (PPP: your own, not the peer address) and the bits value from the ISP or 32 for 6to4 |
| IPv6 Customer prefix: | / |
Link Local Ipv6 Address Example
convert the ISP prefix and public IPv4 to a IPv6 customer prefix
convert the IPv6 customer prefix to ISP prefix and public IPv4 (the provider prefix length will be used as is)
Teredo IP Decoding
Teredo client IP:| Teredo prefix: | 2001::/32 |
| Teredo server: | ? |
| Teredo Flags: | ? |
| Client public IPv4: | ? |
| Client public UDP port: | ? |
IPv6 Addresses and Networks
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MAC -- EUI-64 Converter
With Auto-Configuration the 64-bit host ID (also called EUI-64 in IPv6 speak) of an IPv6 address is generated from the MAC address of the network card. This tool allows to convert between MAC and EUI-64.| 48bit MAC: | Please use dashes or colons to separate bytes |
| 64bit Host ID: | Please use IPv6 notation with ::/64 as prefix |
Host Address
| IP: | / |
| Network Prefix: | / |
| Host ID: | |
| MAC: | 00-11-22-33-44-55 |
Ipv6 Link Local Address Calculator Online
JS Addr Calc revision 20120802
© Konrad Rosenbaum, 2012
This script is protected under the GNU GPL version 3 or at your option any newer.
Please mail patches to me (konrad@silmor.de) if you have any interesting additions for it.
