I don't think I have ever seen this happening when I have used Wireshark to view the traffic:
It starts from 192.168.0.2 and loops to 192.168.0.255, then starts it all over again, endlessly.
Is this normal? Or my router just got crazy?
It's not your router; most likely this is some computer on your network (whether it's yours or some other box's is hard to tell from the context) using the Simple Service Discovery Protocol (SSDP). The purpose of this protocol is:
It's like walking into a large, dark room and yelling, "Anybody home"?
However, the frequency of this could be a problem if it is happening ridiculously often. Try and measure how much bandwidth this is occupying, if you can. If it's happening many times per second, you should probably care. Or if it's occupying a lot of bandwidth or slowing down your network, you should probably care.
Some routers use such periodic ARP queries to detect which IP addresses are in use on the network – for displaying a device list, or for excluding IP addresses of statically-configured devices from the DHCP pool.