If you have ip helper on router interface, the router forwards the packet to the ip address specified. The above port by the way is used for netbios. Router doesn't generate the packets, it will forward only when you have ip helper turned on.
You can turn off specific ports though. check the ip helper documentation on CCO
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...