This software updates : System/Library/Extensions/IONetworkingFamily.kext/Contents/PlugIns (module) AppleBCM5701Ethernet.kext

If you're worried about it not working then backup the AppleBCM5701Ethernet.kext file before updating by navigating to the IONetworkingFamily.kext, control clicking and showing the package contents, then going to the AppleBCM5701Ethernet.kext and option copying it to the desktop prior to installing the update.

You can check if your system is using this in the first place by looking in system profiler>extensions, and seeing if AppleBCM5701Ethernet.kext is Loaded. If you system is working and then you update and it fails, check if this is loaded before posting a bug, then just revert by copying the previous version back (you may need to kill your ethernet connectin to do this, but that's the file you need).