Techie,
It was my understanding that 300' would be the cutoff. I would expect that even if we are close we will just have less bandwidth. Witch compaired to what is going on now would be a hughe improvment.
ob
If the link fails, it won't be a "just have less bandwidth" failure--it will fail by having a high error rate, which results in dropped packets, which results in end-to-end retransmissions. This is a Very Bad Thing(tm).
However, 285' shouldn't be a problem. As techie pointed out, the maximum length of a 100 megabit Cat5 segment is 100 meters, or around 330'. Assuming that the everything is installed properly, that should work with no problem.
Using Cat6 cable will probably provide you a bit of extra insurance, but isn't really necessary, because the connection is designed to operate flawlessly across 100m of Cat5 cable.
To expand a bit on one of techie's comments, 100m is a hard limit for a half-duplex link. This is because of the "slot time" built into the Ethernet retransmission algorithm. If you make the length longer than that, you will have collisions that aren't detected, resulting in lost packets. Full duplex, on the other hand, doesn't use use the collision detection and backoff algorithm, so there isn't a hard limit as there is with half-duplex. So one can stretch beyond the 100m spec, but it is definitely not recommended practice.
I note that normally hubs are half-duplex, and switches are full-duplex.
techie, I agree that fiber isn't a bad idea between buildings. However, the original Ethernet installation at PARC saw around a 90V difference in ground potential from one end of the coax to the other, so we specified something like 2000V isolation in the coupling transformers when we wrote the standard. This isolation was carried over into the BaseT specs. So there really shouldn't be any problem using copper between two buildings, unless there might be more than 2000V difference in ground potential between the buildings. (In which case you have much, much larger problems to worry about...)
