We are attempting to use copper to fiber Black Box transceivers to connect to a remote site (3560). The transceiver can be powered by PoE or an AC adapter. We are attempting to use both, with the AC as a back-up. Is this the best option? or is PoE extremely reliable? If we should have redundant power, are there any commands where the switch would err-disable the port, but then immediately re-establish the port?
PoE is as reliable as the switch that provides it - so from a risk point of view there are a bunch of things to look at, such as UPS, dual-power supplies, dual supervisors (if applicable), etc. The line card (or port) itself which supplies PoE is always going to be a single point-of-failure. You have to weigh up the cost of providing resilience (in this case the local AC supply to the convertor) with the cost of downtime.
If it's easy to hook it up to an external supply then it's probably a no-brainer but if you need to rewire a whole building to get a power socket then it's a much harder decision.
Regarding the last point about err-disabling, I'm not quite sure what you're after there, could you elaborate?
PoE can put the port into err-disable, just like port security. With port security, you have several options after the rouge MAC address is discovered, but there doesn't seem to be as many options for err-disable caused by PoE issues.
I guess the bottom line is: is it worth the effort to resolve this problem, or should we just go single-power-source from the switch?
Is the concern that a glitch in the inline power causes the port to err-disable? I wouldn't rule this out but I'd say it's unlikely. However, most Cisco switches (apart from low end ones) have some kind of auto-recovery facility that will auto-enable the port after a configured amount of time (the 3560 can do it on a cause basis).
If the link is so important that you can't afford it to be unavailable then you'll have a backup link - adding dual power to a single link just won't buy much.
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...