363-206-285
Maintenance Description
9-30 Issue 3 June 2001
The user can set a VT1.5 signal degrade threshold using the set-vt1 and
rtrv-vt1 commands at a drop node on a VT path protected ring. Similarly, the
user can set an STS-1 signal degrade threshold using the set-sts1 and rtrv-
sts1 commands at a drop node on an STS path protected ring. Note that
although previous equipage-based restrictions on the provisioning of these
parameters have been removed, the signal degrade threshold will only be active
on OLIUs that support it (22D-U, 22G-U/22G2-U, 27G-U/27G2-U, 22F2-U, 24G-U
and 29G-U).
Under normal conditions, both incoming SONET path signals to the switch
selection point are of high quality, and the signal can be selected from either ring.
A failure or a transmission degradation on one of the rings requires that the other
ring path be selected, and requirements specify that this path selection must
occur within 60 milliseconds after a hard failure condition. Figure 9-14(b) shows
how traffic is switched when a dual-fiber cut occurs. Ring releases provide
nonrevertive switching to minimize the impact on critical customer services by
giving the service provider control when, and if, the critical service should revert to
a particular ring. A manual path protection switching command allows switching
back to the original path for ease of ring maintenance. Refer to the switch-
path-vt1 or switch-path-sts1 commands in Section 11, "Commands and
Reports."
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