Numbers: FC World Wide Names (WWNs)

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)