This one shouldn't take a moderator, your DSM-510 is trying to join a few multicast groups. I will throw a link to the wiki on multicast at the bottom of this post. Long story short it is trying to join a couple of common multicast group, one I recognize offhand as being the group for "all network devices" and you should see your Windows PCs will cause the same message. This only applies to addresses in the range of 224.0.0.0-239.255.255.255 which are all the small number of repeat messages.
As for the other addresses I can tell you that they are Chinese IPs belonging to a organization call CNC group you can use the APNIC whois (link below) to check them out for yourself. Near as I can tell they are a Chinese ISP. As for why the DSM-510 is pinging them, could be a number of reasons, it wouldn't freak me out terribly, for all I know this is how they are checking for firmware on this device is a ping with a payload in the echo indicating update available. After all isn't D-Link suppose to be a Taiwanese company (backed up by the fact that the investor relations portion of their site will take you to financial statements saying they are in Taiwan)?
On second thought I have a better question why is your router blocking outbound pings?
http://en.wikipedia.org/wiki/Multicast
http://wq.apnic.net/apnic-bin/whois.pl