Hi, after looking into webmaster tools, i discovered that 3 of my websites suffered of a drop in traffic on the very same day (the 15th of november 2012). Those 4 websites were hosted on the same IP. I looked at penguin and panda updates i did not find anything. I looked into incoming links. One of the 3 websites did not receive any new incoming links. The only thing i noticed was those 4 websites had reciprocal links between each other. Some reciprocal links were site-wide links. However, the connections between them were logical I checked all my incoming links, i did not find any banned domains with no pagerank or no google results. Did someone face this kind of situation? For me, it is the proof of a cross-linking penalty. Furthermore, you can see on the webmaster tools graph that nothing special happened in the days following the drop.