Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual page 979

To prevent route flaps from happening before a defect has been outstanding for
a longer period than would be expected for an Automatic Protection Switching
(APS) cutover
To reduce the number of interface transitions
NOTE: On M Series and T Series routers with Channelized SONET IQ PICs and
Channelized SONET IQE PICs, the SONET defect alarm trigger
is not supported.
When you apply a "down" hold time to a defect, the defect must be present for at
least the hold-time period before the interface is marked down. When you apply an
"up" hold time to a defect, the defect must remain absent for at least the hold-time
period before the interface is marked up, assuming no other defect is outstanding.
When you configure hold timers and the interface goes from up to down, the interface
transition is not advertised to the rest of the system until the interface has remained
down for the hold-time period. Similarly, when an interface goes from down to up,
the interface transition is not advertised until the interface has remained up for the
hold-time period.
To configure hold timers, include the
interface-name sonet-options trigger defect]
[edit interfaces interface-name sonet-options trigger defect]
hold-time up milliseconds down milliseconds;
The time can be a value from 1 through 65,534 milliseconds.
When you configure defect hold times, you should note the following:
You can configure an up hold time, a down hold time, or both.
Each interface on a SONET/SDH PIC controls certain aspects of the SONET/SDH
overhead. For example, when you configure an OC48 PIC to be nonconcatenated,
four interfaces are created. Each interface has its own path overhead. However,
all four path interfaces share the same physical, section, and line overhead. This
means the following:
Each interface s path trigger configuration is honored.
The physical, section, and line trigger configuration for the primary interface
( so-fpc/pic/slot:0 ) is applied to all four interfaces.
Therefore, if you configure the
LOS trigger, when an LOS event occurs, all four interfaces remain up until the trigger
expires, and then all four interfaces are marked down.
The hold timers on the SONET/SDH defects are applied in addition to any other
hold timers you configure on the interface. For example, if an interface is up
and you configure a SONET/SDH trigger down hold time of 100 milliseconds and
an interface down hold time of 250 milliseconds, when the SONET/SDH defect
occurs, the SONET/SDH trigger timer starts. After 100 milliseconds, assuming
Chapter 61: Configuring SONET/SDH Interfaces
hold-time statement at the
hierarchy level:
interface to have a hold time for the
so-fpc/pic/slot:0
Configuring SONET/SDH Physical Interface Properties
hold-time statement
[edit interfaces
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