First and End MAC Address from OUI using PHP

September 19, 2022

To calculate the first and end MAC address from OUI using PHP, we use a formula that appends the hexadecimal values 00:00:00 and FF:FF:FF to the OUI, respectively. This formula works because the first three bytes of the MAC address correspond to the OUI, and the last three bytes can be any value from 00-00-00 to FF-FF-FF. Therefore, you can get first and last MAC address by appending the minimum and maximum values in last of OUI.

An OUI (Organizationally Unique Identifier) is a 24-bit number that uniquely identifies a vendor or manufacturer of network equipment. First three bytes represent the OUI (Organizationally Unique Identifier) and the last three are device identifiers. Network equipment vendors use OUI to ensure the uniqueness of MAC addresses across different networks.

First and End MAC Address from OUI

For example, if the OUI is 00-11-22, the first MAC address in the block would be 00-11-22-00-00-00, and the end MAC address in the block would be 00-11-22-FF-FF-FF. Network equipment vendors use these MAC addresses to identify network devices within their assigned block of MAC addresses.

PHP Code Example for

$prefix = '00:11:22';

$prefix = str_replace(':', '', $prefix); // remove any colons from the prefix
$prefix = str_replace('-', '', $prefix); // remove any hyphens from the prefix

// calculate the number of remaining digits after the prefix
$remainingDigits = 12 - strlen($prefix);

// generate the maximum MAC address by setting all remaining digits to 'f'
$maxMAC = $prefix . str_repeat('f', $remainingDigits);

// generate the minimum MAC address by setting all remaining digits to '0'
$minMAC = $prefix . str_repeat('0', $remainingDigits);

// format the MAC addresses with colons for readability
$maxMAC = implode(':', str_split($maxMAC, 2));
$minMAC = implode(':', str_split($minMAC, 2));

return array($minMAC, $maxMAC);

This code takes a MAC address prefix (e.g., 00:11:22) as input and calculates the first and last MAC addresses in the range. It assumes that the remaining digits in the MAC address range from 00 to ff, inclusive. The function returns the minimum and maximum MAC addresses as an array.

The first MAC address in the block is obtained by taking the OUI and appending the hexadecimal values 00-00-00.
The end MAC address in the block is obtained by taking the OUI and appending the hexadecimal values FF-FF-FF.

In summary, the first and end MAC addresses from an OUI can be calculated by appending the hexadecimal values 00-00-00 and FF-FF-FF to the OUI, respectively.