桌面和移动网站，相同的网址，如何相互链接？

Question

We are in the process of getting a mobile version of our site up and going. For various reasons we are investigating the "same URL, different content" structure via User Agent detection. No problems there, we're comfortable setting a cookie depending on UA settings and using this cookie to determine what content/css/etc to use.

The problem is though, we want to provide a link back to desktop version from the mobile page, and vice versa. We don't want to just link to the homepage, but to the same page, just in the other environment.

We were thinking about making the links contain a $_GET parameter

<a href="....html&mob=1">...</a> //mobile page, user wants desktop, AND
<a href="....html&mob=2">...</a> //desptop page, user wants mobile

Then in our prepend we would check for the $_GET parameter, if found, depending on it's status, to set or unset our cookie, and then do a redirect to the HTTP_REFERRER (the same page as they were just on).

The question is though, does anyone know how this will affect SEO/bots?

Is there a best practice for serving different content on the same url, AND have a link to the other version.

Any input would be greatly appreciated. Thanks in advance!

UPDATE - OUR CODE FOR DETECTING MOBILE USERS AND THEIR CHOICE

// First page load, redirect if mobile
if(!isset($_SESSION['mobile'])){
    // SCRIPT SOURCED FROM: http://code.google.com/p/php-mobile-detect/
    include_once(INCL_PREP . "lib/Mobile_Detect.php");
    $detect = new Mobile_Detect();
    // if mobile device, but NOT tablet (they handle desktop versions just fine!)
    if ($detect->isMobile()  && !$detect->isTablet()) {
    $_SESSION['mobile'] = 1;
    $redirectURL= ...; // code removed for sake of space and relevancy
    header("location:$redirectURL");
}else{
    $_SESSION['mobile'] = 2;
}
// Get the $_SESSION['mobile'] status by the $_GET parameter
if($_GET['mobile'] == "on"){
     $_SESSION['mobile'] = 1;
}else{
        $_SESSION['mobile'] = 2;
}

So, the mobile version has $_GET a get parameter, and using this and $_SESSION we can auto redirect on page load, and they can also swap between the mobile and desktop version without a problem.

Thanks to the input people.

Answer 1

'Technically' you're not using the "same URL" - query string variants are actually treated as different URLs by search bots.

If you're trying to manage different URLs for mobile/desktop users and want to ensure that Google "sees" the right version, then read the following resource: https://developers.google.com/webmasters/smartphone-sites/details

Half way down is the explanation on how to use the rel="alternate" and rel="canonical" for exactly the scenario you are describing.