Use Loopback Testing for SONET Interfaces

This chapter describes the steps for using loopback testing to isolate SONET interface problems. (See Table 29.)

Table 29: Checklist for Using Loopback Testing for SONET Interfaces

SONET Interface Loopback Testing Tasks	Command or Action
Diagnose a Suspected Hardware Problem with a SONET Interface
Create a Loopback
Create a Physical Loopback	Connect the transmit port to the receive port.
Configure a Local Loopback	`[edit interfaces` `interface-namesonet-options] set loopback local show commit`
Set Clocking to Internal	`[edit interfaces` `interface-name] set clocking internal show commit`
Verify That the SONET Interface Is Up	`show interfaces so-fpc/pic/port`
Clear SONET Interface Statistics	`clear interfaces statistics so-fpc/pic/port`
Check That the Received and Transmitted Path Trace Are the Same	`show interfaces so-fpc/pic/port` `extensive`
Force the Link Layer to Stay Up
Configure Encapsulation to Cisco-HDLC	`[edit interfaces` `interface-name] set encapsulation cisco-hdlc show commit`
Configure No-Keepalives	`[edit interfaces` `interface-name] set no-keepalives show commit`
Verify the Status of the Logical Interface	`show interfaces so-fpc/pic/portshow interfaces so-fpc/pic/port` `terse`
Ping the SONET Interface	`ping interface so-fpc/pic/port local-IP-address` `bypass-routing count 1000 rapid`
Check for SONET Interface Error Statistics	`show interfaces so-fpc/pic/port` `extensive`
Diagnose a Suspected Circuit Problem
Create a Loop from the Router to the Network	`[edit interfaces` `interface-namesonet-options] set loopback remote show commit`
Create a Loop to the Router from Various Points in the Network	Perform Steps 2 through 8 from Diagnose a Suspected Hardware Problem with a SONET Interface.