Blueyonder Broadband connection oddities

I hope ive posted this in the correct place...

I have just downgraded from 1meg to 512k cable service here in the UK.

I noticed that my Belkin router is continously blocking an IP address that is coming from my ISP (Ive monitored whilst filesharing, http downloading, doing nothing and its a continous barage (attempted DOS blocked every 3/4 s)), Blueyonder... did a traceroute and I get the same IP address, yet my real IP address to the internet is different... I assume its a shared connection, does'nt worry me, as my blueyonder has no caps/limits on this service, but wondered if this is better/worse/no different for security and also any implications to my filesharing activities, as thats the only compromise i have in my router (forwarded port).