Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: WIS Loopbacks


The clause as it is currently written is not capable of
sending the AIS condition. Also, sending all ones or all
zeros doesn't require a full WIS transmit function.
This can simply be a conditional input to the PMA Service
interface. This allows the (one and only) transmit
function to continue to be used for generating the SONET
frame to be looped back to the WIS receive function.

Is it your recommendation that the WIS be modified to
include the capability of sending AIS (for loopback or
other indications? This was not voted on yesterday during
the WIS clause discussion so will have to be brought up
in front of P802.3ae this afternoon to become part of D2.0.


Tim Warland wrote:
> With respect to the proposed loopback mode for the WIS, it
> is currently defined that the WIS shall loop data received from
> the PCS layer through the WIS transmitter back to the WIS
> receiver to the PCS.  The question in today's WG was what
> to send over to the PMD.
> To clarify my suggestion, the PCS data received by the WIS would
> by forwarded to the PMD using the (one and only) WIS transmitter
> block.  However, some signalling would have to be imposed to
> ensure the far end was aware of a local loopback condition (likely
> the reason for the loopback and it is also probable that there would
> not be a far end in this condition).  I suggested the WIS could
> set an AIS condition in the SONET overhead which would
> signal the far end to ignore the data in the SPE. It may however be
> a requirement for the PCS layer or higher which called for the
> loopback to signal the far end for this condition.
> This is in contrast to the suggestion that the (one and only)
> transmitter
> block be configured to send all ones or all zeros to the PMA for
> it to figure out during a loopback condition.
> In addition (to throw it on the reflector) as far as I know, there is
> no test pattern available to test the WIS in osolation.  This nullifies
> the requirement to develop a WIS test pattern.
> Tim Warland
> Nortel Networks.

Benjamin Brown
2 Commerce Park West
Suite 104 
Bedford NH 03110
603-641-9837 - Work
603-491-0296 - Cell
603-647-2291 - Fax
603-798-4115 - Home Office