Route and Pagination

In your example, is tag the controller and page method?

In that case you need to add one more argument to router code - $2 to get page number

PHP Code:

$route['tag/(:any)/(:num) = 'tag/page/$1/$2'; 


And controller class:

PHP Code:

class Tag extends CI_controller
{
    public function page($tag = false, $page = 1)
    {
        // ... your code here
    }
}