A problem we have around the shop is patch cords in unknown condition. No information is kept about any used cord, except maybe its length. Is it still good? Can it support gigabit speeds, 10/100, or should it be relegated to the dust bin? Good commercial cable certifiers are expensive, so we looked around for something cheaper. The really cheap ones are not very good.
We finally found this handheld device, called the
Real World Certifier, which has been remarkably useful for its cost. It's small and easily portable; great for field testing. It just uses an electrical signal, not actual packets, but for most of our needs, that's enough. We use it all the time for certifying used or home-made cables, determining lengths of coiled cables (without rolling them out on the floor!), troubleshooting suspect cables, tracing cable routes, etc.
Inexpensive and extremely handy. Highly recommended.
-Ken
[Disclaimer: I hope this doesn't sound too much like a shill. It's a recommendation for a little-known product which we find quite useful. I have no affiliation with the manufacturer, except as a satisfied customer.]