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SONET APS Question

  • From: Gary Tam <gtam@lanterncom.com>
  • Date: Thu, 6 Jun 2002 20:11:55 -0400

Title: SONET APS Question
This is an MPLS issue and should be not concerned with this forum.
 
To answer your question, first of all, the K1/K2 is capsulated on the STS-1 Line Overhead. So
both the working and protection paths will receive K1/K2 in normal condition. Secondary,
it is up to the protection scheme and mode to decide whether to revert back to the working
line or not when the working line becomes healthy again. If it is revertive and working path state
changes from fail to ok, traffic will be switched back to the working path after a wait-to-restore 
period.  If it is non-revertive, of course it will not.  So if the working is healthy, traffic is on
the protection path and and the protection path is faulty, traffic will switch back to the working
path for sure.
-----Original Message-----
From: Nakum, Vimal [mailto:vnakum@iPolicyNet.COM]
Sent: Thursday, June 06, 2002 6:09 PM
To: 'mpls@uu.net'
Subject: SONET APS Question


Hi,

In SONET standards, it is mentioned that K1/K2 bytes carry APS Protocol bytes on protection line when signal degrade happens on working line. Suppose after some times, working line becomes up. Now, when signal degrade happens on protection line, how link switches back to working line ? Does working line carries K1/K2 bytes, indicating switchover to working line  or  both ends assume that now transfer will be on working line ?

Thanks,

Vimal Nakum