Extreme Networks WM-4T1i manual Monitoring T1 Physical Link, Loopback

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Configuring the T1 Physical Link

Monitoring T1 Physical Link

T1 devices have a built-in facility designed for troubleshooting the physical link, called loopback. The T1 link can also be monitored using show commands to display the current configuration of the link, any alarms on the link, link statistics, and link errors.

Loopback

The T1 device can be set up to loopback, that is, return a transmitted signal back to the sender so it can be compared with the original. There are several different types of loopback available to test different parts of the device and the line, specified in the T1 standards.

Local T1 Port

Remote T1 Port

Data in

Data out

Data out

Data in

Framer

Framer

Data with framing

Figure 2-1:Normal operation of T1 link

XM_010

During normal operation of a T1 link, as the local data stream enters the framer, the appropriate framing bits are inserted into the data, and the framed signal is transmitted to the remote end. At the remote end, the process is reversed as the framing bits are discarded and the data stream is passed to the remote system.

Loopback can be enabled on the near-end or the far-end of the link. The near-end loopback modes are controlled directly by the hardware on the near-end. Far-end loopback modes require the cooperation of the far-end hardware. A message is sent to the far-end to cause it to enter a far-end loopback mode. When loopback is enabled on a T1 port, the green port LED will blink.

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WM-4T1i Module Installation and User Guide

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Contents WM-4T1i Module Installation and User Guide Page Contents Index Index of Commands Preface IntroductionConventions Text ConventionsRelated Publications Viii WM-4T1i Module Installation and User Guide Installing the WM-4T1i Module OverviewInstalling the WM-4T1i Module Ports and Connectors WM-4T1i Module LEDs1WM-4T1i Module LEDs LEDInstalling the WM-4T1i Module Software Use image primary secondary Configuring the T1 Physical Link Configuring T1 Physical linkAlarms Cable lengthFacility Data Link Clock SourceLinecoding FramingInband Loopback Detection 1T1 Port Configuration Commands Yellow AlarmsT1 Port Configuration Commands Data Data out Framer Data with framing Monitoring T1 Physical LinkLoopback Data Data out Framer Framer Data outFar-End Loopback Modes 5Remote line loopback mode 6Remote payload loopback modeT1 Port Monitoring Commands 2T1 Port Monitoring Commands2T1 Port Monitoring Commands Configuring the T1 Physical Link Configuring PPP and Mlppp Multilink PPP and Multilink Groups Configuring a PPP/MLPPP Link AuthenticationEncapsulation PPP User AccountsPPP/MLPPP Configuration Commands 1PPP/MLPPP Configuration CommandsPPP/MLPPP Configuration Examples Configuring a Bridged PPP/MLPPP Link Example2PPP/MLPPP Show Commands Monitoring PPP/MLPPP LinksSwitch Configuring a Routed PPP/MLPPP Link ExampleSwitch #1 2IPCP multilink example Index NumericsPAP Index of Commands Ii Index of Commands