[c-nsp] Switch Port Question

[Pete Templin]

On 1/24/11 7:48 PM, Aaron Riemer wrote:

[snip]

> Obviously this is not the case. Therefore my question is what determines if
> a port is physically "UP"? What physical checks are done by the switch port
> and how does it determine if media is attached? Is a frame received over the
> fibre initially which brings the port up but a subsequent failure will go on
> undetected?

Port "up" (for many forms of Ethernet, newer technologies 
notwithstanding) is unilateral: if port is receiving properly-formatted 
pulses, port is up.  Unfortunately, "properly-formatted" has a very 
small definition in the Ethernet world.  TDM technologies (DSx, OCx) 
have better alarm capabilities integrated into "properly-formatted", and 
therefore provide a more complete end-to-end status (partially because 
of their point-to-point nature).

I miss working with TDM.

pt