Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual page 975

For channel 0 on channelized interfaces only, you can include the
at the
setting configured for channel 0 applies to all channels on the channelized interface.
The
configuration of other channels. To configure loopbacks on individual channels, you
must include the
each channel. This allows each channel to be put in loopback mode independently.
For example, for DS3 channels on a channelized OC12 interface, the
loopback
configuration for channels 1 through 11. The SONET/SDH loopback configured for
channel 0 applies to all 12 channels equally. To configure loopbacks on the individual
DS3 channels, you must include the
for each channel. This allows each DS3 channel can be put in loopback mode
independently.
You can determine whether there is an internal problem or an external problem by
checking the error counters in the output of the
command:
Example: Configuring SONET/SDH Loopback Capability
To determine whether a problem is internal or external, loop packets on both the
local and the remote router. To do this, include the
cisco-hdlc
loopback local
level. With this configuration, the link stays up, so you can loop ping packets to a
remote router. The
PIC just before the data reaches the transceiver.
Configuring the SONET/SDH Path Trace Identifier
The SONET/SDH path trace identifier is a text string that identifies the circuit. If the
string contains spaces, enclose it in quotation marks.
By default, the JUNOS Software uses the router and interface names for the path
trace identifier. Depending on the router and interface names, the default path trace
[edit interfaces interface-name interface-type-options]
statement is ignored if you include it at this hierarchy level in the
loopback
channel-type-options loopback
statement is supported only for channel 0; it is ignored if included in the
user@host> show interfaces so-fpc/pic/port extensive
statements at the
statement at the
loopback local
[edit interfaces]
so-1/0/0 {
no-keepalives;
encapsulation cisco-hdlc;
sonet-options {
loopback local;
}
unit 0 {
family inet {
address 10.100.100.1/24;
}
}
}
Chapter 61: Configuring SONET/SDH Interfaces
statement in the configuration for
t3-options loopback
show interface interface-name extensive
no-keepalives
[edit interfaces interface-name]
[edit interfaces interface-name sonet-options]
statement causes the interface to loop within the
Configuring SONET/SDH Physical Interface Properties
statement
loopback
hierarchy level. The loopback
sonet-options
statement in the configuration
and encapsulation
hierarchy level, and the
hierarchy
905