Think about it -- are they really provisioning two circuits, leaving one available as a backup? Of course not!

I think you missed on of my points, which was APS on the trib side of the ADM, only a small mention of APS on the network side. If you can't figure out whether you've two circuits sitting there you've got bigger problems...

This may be a useful feature for voice circuits, where most of the capacity sits idle most of the time. It's worse than useless for data.

Again, I think you're missing the application wrt it residing on the trib side of the ADM -- to protect against router failures -- continuing to use the same network portion (i.e. the expensive portion) of the connection.

APS was designed to protect against the failure of the electronics for a single fiber in a cable. Often, a dozen other circuits are "protected" by a single APS. It's a ripoff.

Perhaps in your experience, though I can argue quite the contrary, especially when your company owns the the transmission facilities. Though again, I was referring primarily to local protection against router failure on the trib side of the ADM.

Of course, the usual failure mode is backhoe fade, not electronics. In which case, that APS circuit was cut along with the rest.

Of course, backhoes don't normally work inside PoPs, which is the application of APS I was referring to. Routers do fail though (often more than links), and APS has been demonstrated to work relatively well for protecting against such failures.

For transoceanic links, diverse APS is even more unlikely, and unless you are paying serious money, you won't be a priority over the other hundred customers that are sharing that APS circuit.

Not on the trib side, when protecting against router failures.

Diverse links _are_ the only _real_ protection. You might even get what you pay for.... And in the short term, you at least get twice the bandwidth

Again, APS w/two local links to an ADM sufficiently protect against a local router failure. -danny