Use Loopback Testing for Multichannel DS-3 Interfaces

This chapter describes using loopback testing to isolate Multichannel DS-3 interface problems. (See Table 53.)

Table 53: Checklist for Using Loopback Testing for Multichannel DS-3 Interfaces

Multichannel DS-3 Interfaces Loopback Testing Tasks	Command or Action
Diagnose a Suspected Hardware Problem with a Multichannel 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 name (t3-options | t1-options)] set loopback local show commit
Verify That the Interface Is Up	show interfaces (ds-fpc/pic/port:channel:channel | t1-fpc/pic/port:channel)
Clear Interface Statistics	clear interfaces statistics (t1-fpc/pic/port:channel | ds-fpc/pic/port:channel: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 (ds-fpc/pic/port:channel:channel | t1-fpc/pic/port:channel)
Ping the Channelized Interface	ping interface (ds-fpc/pic/port:channel:channel | t1-fpc/pic/port:channel) local-IP-address bypass-routing count 1000 rapid
Check for Interface Error Statistics	show interfaces (ds-fpc/pic/port:channel:channel | t1-fpc/pic/port:channel) extensive
Diagnose a Suspected Circuit Problem
Create a Loop from the Router to the Network
Loop the Entire T3 Interface towards the Network	[edit interfaces interface-name t3-options] set loopback remote show commit
Loop a Particular T1 Channel towards the Network	[edit interfaces interface-name 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 Multichannel DS-3 Interface.