There can't be many network managers who haven't at some point found a stash of MP3s on their network. Whether they were downloaded legally or illegally - and it was probably the latter - they are taking up your storage space and they probably consumed your download bandwidth too.
That situation is going to get a whole lot worse as IP TV moves in. Streaming video can take huge amounts of bandwidth - as today's network admin is likely to discover every time there's a major sporting event - and if users decide to save stuff, it requires much more storage too.
Of course, for TV companies and other content providers, these are all challenges to overcome. Their target is of course the legitimate home user, and here's a couple of samples of what they are up to that could affect your networks over the next few months and years.
The heavy demands of video-on-demand
The big challenge for the media companies and content owners when it comes to video-on-demand (VoD) has been the cost of distribution, says Andrew Parker, the CTO of peer-to-peer (P2P) caching specialist CacheLogic.
He points out that if a song in MP3 format is 5MB and sells for 70p, that gives it a value of £140 per GB and makes it worth streaming. However, a 90 minute video on DVD is perhaps 3.5GB and costs £10 to buy, making it worth just £3 per GB - and rental rates are even lower, of course.
"DVDs are far more expensive to distribute than audio," he says. "It makes the economics of VoD much more questionable, and high-definition TV will make this problem even worse."
Plus, he adds, there is the hugely increased load on the Internet backbones that all this video represents, whether it is streamed from servers or shared using P2P technology.
Parker has an axe to grind, of course - his company has come up with VelociX, a DRM-capable caching system which it is offering as a service to content owners, allowing them to securely host copies of their DVDs and other content within ISP networks.
Whether VelociX takes off or not - and CacheLogic's ambition to become the iTunes of VoD is a pretty lofty one - it shows the way that things are going. Content is getting richer, and one way or another, the ISPs and content providers will find ways of getting it out there, onto your network and many others like it. And you are going to have to deal with that.
Next - watch TV anywhere
Meanwhile, your users are going to be finding more ways to load the LAN down. One of them could well be watching free TV - not streamed from the broadcaster or picked up from an aerial, but from their home systems.
USB TV tuners are pretty well-known now, and are capable of turning a PC into a personal video recorder (PVR), able to save TV to the hard disk and replay it later. Now, you can't even block their use by gluing up the USB sockets of your PCs - USB TV tuner manufacturer Hauppauge Digital has done a deal with a software developer called Orb Networks that allows live or recorded TV to be sent over the Internet to any web-capable device - even a PDA or mobile phone.
In an analogy with the time-shifting that video recorders made possible, Hauppauge's UK MD Yehia Oweiss calls this place-shifting. "Appointment TV is dying," he argues. "Place-shifting is the new frontier - watching recorded TV where you want it, and moving live TV out of the home."
The new system is called TV Anywhere, and uses the home PC to provide content, whether that be TV, audio or photos, which it streams out over broadband. Of course, it is limited by your upstream bandwidth, which for home broadband is almost always less than the downstream bandwidth, but Hauppauge claims that the Orb software adapts to both the speed available and the connecting device.
The admin strikes back
So what's going to stop this stuff from bogging down your network? Multicasting is fine if you're an ISP broadcasting films on the half-hour, or if the video in question is the chairman's weekly pep-talk to staff, but won't help much with ad-hoc rich media.
If you do want to let it through, or at least let some of it through and control the rest, a combination of bandwidth-shaping and P2P caching may be an option. Andrew Parker says that many P2P clients now include CacheLogic's Cache Discovery Protocol, CDP, allowing them to divert requests to a local store instead of out over the Internet.
He warns though that, for the moment, P2P caching is lots different from web caching. "Web caching has become a commodity, for example NetApp and Inktomi have stepped out of that business," he says. "P2P caching is extremely hard to do though. But we will still need it until there's better infrastructure world-wide."