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 addresses and subnets calculation CCTV Calculator is a tool designated for camera system basic parameters determination and testing. It enables easy calculation of an appropriate lens focal length, camera viewing angle, IP camera bandwith, storage capacity for records archiving and of other camera system parameters. 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. This calculator can be used for IPv6 in the same way VLSM is used to plan an IPv4 network. Remember, the size of IPv6 can be huge. This calculator can crash your browser if you attempt to have it calculate billions of subnets! Because of this, only the first 999 subnets are displayed. Use the above calculator to plan your IPv6 networks.
To uniquely identify devices in the network, they must be assigned a link-local IPv6 address. This address is based on the interface identifier (IID), which is derived from the Bluetooth Device address. You should be familiar with the IPv6 addressing model as defined in specification RFC 4291 to understand the following content.
Link-local addresses are designed to be used for addressing on a single link for purposes such as automatic address configuration or when no routers are present. Routers are not allowed to forward any packets with link-local source or destination addresses to other links. Therefore, to communicate with the outside world, a global address must be created; see Distributing a global IPv6 prefix for instructions on how to do that.
Ipv6 Local Link
Link-local addresses contain the prefix FE80::/10 and a 64-bit interface identifier (IID). The link-local address is automatically assigned to the interface and has a role similar to an IPv4 local address, for example, 192.168.0.0/16.
Creating an IPv6 link-local address comprises three steps:
- Transforming the Bluetooth device address into Modified EUI-64 format
- Transforming the Modified EUI-64 address into an IID
- Transforming the IID into a link-local address
- Note
- The steps differ for various Linux Kernel versions and for different Bluetooth Device address types.
Public Bluetooth Device Address
- Create a modified EUI-64 address.
Extend the 48-bit address to a 64-bit address, which is used as MAC address in IPv6. To do this, you must add the bytes 0xFF and 0xFE in the middle of the 48-bit address. - Create an IID.
Set the address as globally unique. Do this by flipping the seventh most significant bit of the first byte (bitmask 0x02). The same result is achieved by an XOR operation with a 0x02 value on the first octet. The resulting ID is the interface identifier. - Create a link-local address.
Add the link-local prefix FE80::/10 to the IID. In this example, the link-local address for the Bluetooth device address 00:11:22:33:44:55 is FE80:0000:0000:0000:0211:22FF:FE33:4455, or simpler FE80::211:22FF:FE33:4455.
Remove Link Local Ipv6 Address
Random Static Bluetooth Device Address
For example, consider the following 48-bit random static Bluetooth address: C0:11:22:33:44:55
- Create a modified EUI-64 address.
Extend the 48-bit address to a 64-bit address, which is used as MAC address in IPv6. To do this, you must add the bytes 0xFF and 0xFE in the middle of the 48-bit address and set the 7th bit of the first octet using 0x02. Therefore, the modified IID is C2:11:22:33:44:55. - Create an IID.
As the address is not globally unique, the universal/local bit in the IID shall be set to 0. Since the modified EUI-64 has this bit set using the OR operation with 0x02, performing XOR operation on this first octet of EUI-64 results provides the desired result. Note that the XOR operation is common for public and random address. - Create a link-local address.
Add the link-local prefix FE80::/10 to the IID. In this example, the link-local address for the Bluetooth device address C0:11:22:33:44:55 is FE80:0000:0000:0000:C011:22FF:FE33:4455, or simpler FE80::C011:22FF:FE33:4455.
- Note
- In order to comply with RFC 7668 (Linux Kernel >= 4.12), set the BLE_6LOWPAN_LEGACY_MODE define in
sdk_config.hto 0. If this define is set to 1, 6LoWPAN module will not be able to decompress packets correctly.
Bluetooth Device Address (Public or Static Random)
- Create an IID.
Extend the 48-bit address to a 64-bit IID, which is used in IPv6 addresses. To do this, you must add the bytes 0xFF and 0xFE in the middle of the 48-bit address. - Create a link-local address.
Add the link-local prefix FE80::/10 to the IID. In this example, the link-local address for the Bluetooth device address 00:11:22:33:44:55 is FE80:0000:0000:0000:0011:22FF:FE33:4455, or simpler FE80::11:22FF:FE33:4455.
When you set up IPv6, you may need to set up your own local, non-routable IPaddresses on your network - similar to the older RFC1918 blocks. RFC-4193 addresses (no punintended) this issue.
Your IP address block assigned should be generated randomly from the fc00::/7block. As IETF hasn't formalized fc00::/8, addresses should be assigned outof fd00::/8.
This means that your resulting IPv6 network will look like:
fdxx:xxxx:xxxx::/48
and you'll have
fdxx:xxxx:xxxx:0:/64 through fdxx:xxxx:xxxx:ffff:/64 as routable blocks withinyour private /48.
The 40 bytes of the /48 (xx:xxxx:xxxx) is supposed to be generated randomly through one of several suggested methods. Burn cd catalina.
Your Private IPv6 network is:
giving you access to the to the following /64s:
This page uses the first method suggested by IETF using the current timestamp plus the mac address, sha1 hashed, and the lower 40 bits to generate your random ULA. Consequently, if two organizations hit this page within the same second, with the same mac address to generate a ULA, they could have identical ULAs.
