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Monitor T1 Interfaces

 

By monitoring T1 interfaces, you begin the process of isolating T1 interface problems when they occur.

To monitor your T1 interfaces, follow these steps:



Display the Status of T1 Interfaces

Purpose

To display the status of T1 interfaces.

Action

Use the following Junos OS command-line interface (CLI) operational mode command to display the status of T1 interfaces:

Sample Output

user@host> show interfaces terse t1*

Meaning

This sample output shows the status of both the physical and logical interfaces. See Table 1 for a description of what the output means.

Table 1: Status of T1 Interfaces

Physical Interface

Logical Interface

Status Description

t1-1/0/0

AdminDown

Link Up

t1-1/0/0.0

Admin Up

Link Down

This interface is administratively disabled and the physical link is healthy (Link Up), but the logical interface is not established. The logical interface is administratively enabled (Admin Up), but is down because the physical link is disabled.

t1-1/0/1

Admin Up

Link Down

t1-1/0/1.0

Admin Up

Link Down

This interface is not functioning between the local router and the remote router because both the physical and logical links are down (Link Down). The interface is not administratively disabled because both the physical and logical links are up (Admin Up).

t1-1/0/2

Admin Up

Link Up

t1-1/0/2.0

Admin Up

Link Up

This interface has both the physical and logical links up and running.

t1-1/0/3

Admin Up

Link Down

 

The physical interfaces is added to the configuration, but the logical link is not configured.



Display the Status of a Specific T1 Interface

Purpose

To display the status of a specific T1 interface when you need to investigate its status further.

Action

To display the status of a specific T1 interface, use the following Junos OS CLI operational mode command:

Sample Output

user@host> show interfaces t1-1/1/0

Meaning

The first line of the sample output shows the status of the link. In this example, the first line shows that the physical link is down. If the first line shows that the physical link is up, the physical link is healthy and can pass packets. If this line shows that the physical link is down, the physical link is unhealthy and cannot pass packets. Also, the output shows loss of frame (LOF) and loss of signal (LOS) alarms active. Any active alarm or defect can cause the interface to be down.



Display Extensive Status Information for a Specific T1 Interface

Purpose

To display extensive status information about a specific T1 interface.

Action

To display extensive status information about a specific T1 interface, use the following Junos OS CLI operational mode command:

Sample Output

user@host> show interfaces t1-1/1/0 extensive

Meaning

The sample output shows where the errors might be occurring. Look at the active alarms and active defects for the T1 interface and investigate the T1 media accordingly. See Checklist for T1 Alarms and Errors for an explanation of T1 alarms.



Monitor Statistics for a T1 Interface

Purpose

To monitor statistics for a T1 interface.

Action

To monitor statistics for a T1 interface, use the following Junos OS CLI operational mode command:

Sample Output

user@host> monitor interface t1-1/0/0

Meaning

The sample output shows that the T1 interface is enabled but the link is down. The bps value is in bytes per second and not bits per second. To calculate bits per second, multiply the bps value by 8.

The monitor command checks for and displays common interface failures, indicates whether loopback is detected, and shows any increases in framing errors. Use information from this command to help to narrow down possible causes of an interface problem.

Note

If you are accessing the router from the console connection, make sure you set the CLI terminal type using the set cli terminal command.

Table 2 lists additional problem situations and actions to help you further diagnose a problem.

Table 2: Problem Situations and Actions

Problem Situation

Action

Framing errors are increasing.

Check the frame checksum sequence (FCS), scrambling, and subrate configuration.

Framing errors are increasing, and the configuration is correct.

Check the cabling to the router and have the carrier verify the integrity of the line.

Input errors are increasing.

Check the cabling to the router and have the carrier verify the integrity of the line.

Note

We recommend that you use this command only for diagnostic purposes. Do not leave it on during normal router operations because real-time monitoring of traffic consumes additional CPU and memory resources.