Most of us know WWNs as 64-bit WWNs, written as 16 hexadecimal digits. The knowledge that there are different formats of WWNs and that there are also 128-bit WWNs is not quite as well known. In this article, therefore, the different formats of WWNs are briefly presented.
The basic structure of 64-bit WWNs looks like this:
+---+----------------+ |NAA| NAME | +---+----------------+ 4-bit 60-bit
The 4-bit NAA (Network Address Authority) field specifies the type of address and the format of the address.
There are a number of different possibilities for the 60-bit NAME field.
1. Format 1 Address (NAA = 0001)
+---+--------+------------------------+ |NAA|Reserved| 48-bit IEEE MAC Address| +---+--------+------------------------+ 4-bit 12-bit 48-bit
In the Reserved (12-bit) field, all bits must be set to 0!
Example:
1 000 00507605326d (To clarify the format, the fields are separated by spaces)
2. Format 2 Address (NAA = 0010)
+---+---------------+-----------------------+ |NAA|Vendor Assigned|48-bit IEEE MAC Address| +---+---------------+-----------------------+ 4-bit 12-bit 48-bit
The 12-bit “Vendor Assigned” field can be used arbitrarily by the manufacturer.
Example:
2 001 00507605326d (To clarify the format, the fields are separated by spaces)
3. Format 3 Address (NAA = 0011)
+---+-----------------+ |NAA|Vendor Assigned | +---+-----------------+ 4-bit 60-bit
The field “Vendor Assigned” (60-bit) is assigned arbitrarily by the manufacturer. Thus, this type of address is not unique worldwide and therefore usually not found in practice.
Example:
3 0123456789abcde (To clarify the format, the fields are separated by spaces)
4. Format 4 Address (NAA = 0100)
+---+---------+--------------+ |NAA|Reserved | IPv4 Address | +---+---------+--------------+ 4-bit 28-bit 32-bit
The “IPv4 Address” (32-bit) field contains a 32-bit IPv4 address.
Example for IP 10.0.0.1:
4 0000000 0a000001 (To clarify the format, the fields are separated by spaces)
5. Format 5 Address (NAA = 0101)
+---+-------+-----------------+ |NAA| OUI | Vendor Assigned | +---+-------+-----------------+ 4.bit 24-bit 36-bit
The OUI (24-bit) field contains the 24-bit IEEE-assigned ID (Organizational Unique ID).
The field “Vendor Assigned” (36-bit) can be assigned arbitrarily by the manufacturer.
Example:
5 005076 012345678 (To clarify the format, the fields are separated by spaces)
6. Format 6 Address (NAA = 0110)
Format 6 addresses are 128-bit addresses and are often used for LUNs on the SAN.
+---+-------+---------------+-------------------------+ |NAA| OUI |Vendor Assigned|Vendor Assigned Extension| +---+-------+---------------+-------------------------+ 4.bit 24-bit 36-bit 64-bit
The OUI (24-bit) field contains the 24-bit ID assigned by the IEEE.
The field “Vendor Assigned” (36-bit) can be arbitrarily assigned by the manufacturer.
The field “Vendor Assigned Extension” (64-bit) can also be assigned arbitrarily by the manufacturer.
Example:
6 005076 012345678 0123456789abcdef (To clarify the format, the fields are separated by spaces)
7. IEEE EUI-64 Address (NAA=11)
In the case of this address format, the NAA field is shortened to only 2 bits, where NAA is 11.
+---+-------------+---------------+ |NAA|OUI shortened|Vendor Assigned| +---+-------------+---------------+ 2-bit 22-bit 40-bit
The “OUI shortened” field (22-bit) is a 22-bit shortened version of the IEEE-assigned 24-bit ID.
(The two least significant bits of the first byte are omitted and the remaining 6 bits are shifted 2 bits to the right to make room for the two NAA bits.)
The field “Vendor Assigned” (40-bit) can be arbitrarily assigned by the manufacturer.
These types of addresses are often used in the area of virtualization, e.g. when it comes to NPIV (N_Port ID Virtualization).
Example:
c05076 0123456789 (To clarify the format, the fields are separated by spaces)