Use Loopback Testing For Channelized DS-3 Interfaces

This chapter describes using loopback testing to isolate Channelized DS-3 interface problems. (See Table 48.)

Table 48: Checklist for Using Loopback Testing for Channelized DS-3 Interfaces

Channelized DS-3 Loopback Testing Tasks	Command or Action
Diagnose a Suspected Hardware Problem with a Channelized DS-3 Interface
Create a Loopback
Create a Physical Loopback	Connect the TX port to the RX port.
Configure a Local Loopback	`[edit interfaces` `interface nam`e (`t3-options \| t1-options)] set loopback local show commit`
Verify That the Interface Is Up	`show interfaces t1-fpc/pic/port:channelshow interfaces t3-fpc/pic/port:channel`
Clear Interface Statistics	`clear interfaces statistics t1-fpc/pic/port:channel`
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 t1-fpc/pic/port:channel`
Ping the Channelized Interface	`ping interface t1-fpc/pic/port:channel local-IP-address` `bypass-routing count 1000 rapid`
Check for Interface Error Statistics	`show interfaces t1-fpc/pic/port:channel` `extensive`
Diagnose a Suspected Circuit Problem
Create a Loop from the Router to the Network	`[edit interfaces t1-fpc/pic/port:channel` `t1-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 Channelized DS-3 Interface.