$re = '/^(?:\D)*(?:(\d{1,3})\/)?(?:(\d{1,3})\/)?(\d{1,3})\/(\d{1,3})$/im';
$str = '1/1/1
XDSL 1/1/1/1
XDSL Port 1/1/1/1
Port 1/1/1/1
Anytext 1/1/1/1
XDSL 1/1/1
XDS 1/1
1/1/1/1
ABC 1/1';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php