session是不能夸主机的，要在多个主机间公用，可以试用cookie，php中试用cookie方法如下：

setcookie('id', $id, time()+62208000, "/",".domain.name");
//otherwise won't work for the first time.
$_COOKIE['id'] = $id;

删除cookie：

setcookie('id', null, 1, "/", ".domain.name");
unset($_COOKIE['id']);

setcookie详解

更新 若需要设置多维的cookie(形如cookie[person][name], cookie[person][id], cookie[person][age])：

$array = array("person" => array("name" => "Ted","id" => 1));
$value = serialize($array);
set_cookie("person", $value);

读取时需要unserialize($_COOKIE['person']);