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Monitoring SONET Interfaces

 

This section includes the following information to assist you when troubleshooting SONET interfaces:

Checklist for Monitoring SONET Interfaces

Purpose

To monitor SONET interfaces and begin the process of isolating SONET interface problems when they occur.

Action

Table 1 provides the links and commands for monitoring SONET interfaces.

Table 1: Checklist for Monitoring SONET Interfaces

Tasks

Command or Action

Monitoring SONET Interfaces
  1. Displaying the Status of SONET Interfaces

show interfaces terse so*

  1. Displaying the Status of a Specific SONET Interface

show interfaces so-fpc/pic/port

  1. Displaying Extensive Status Information for a Specific SONET Interface

show interfaces so-fpc/pic/port extensive

  1. Monitoring Statistics for a SONET Interface

monitor interface so-fpc/pic/port

Monitoring SONET Interfaces

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

To monitor your SONET interface, follow these steps:

  1. Displaying the Status of SONET Interfaces

  2. Displaying the Status of a Specific SONET Interface

  3. Displaying Extensive Status Information for a Specific SONET Interface

  4. Monitoring Statistics for a SONET Interface



Displaying the Status of SONET Interfaces

Purpose

To display the status of SONET interfaces, use the following Junos OS command-line interface (CLI) operational mode command:

Action

user@host> show interfaces terse so*

Meaning

The sample output lists only the SONET interfaces. It shows the status of both the physical and logical interfaces.

For a description of what the output means, see Table 2.

Table 2: Status of SONET Interfaces

Physical Interface

Logical Interface

Status Description

so-1/0/0

Admin Up

Link Up

so-1/0/0.0

Admin Up

Link Up

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

so-1/1/1

Admin Down

Link Up

so-1/1/1.0

Admin Up

Link Down

This interface is administratively disabled. The physical link is healthy (Link Up), but the logical link is not established end to end (Link Down).

so-3/0/1

Admin Up

Link Up

so-3/0/1.0

Admin Up

Link Down

This interface is administratively enabled and the physical link is healthy (Link Up), but the logical interface is not established end to end (Link Down).

so-5/3/0

Admin Up

Link Down

so-5/3/0.0

Admin Up

Link Down

This interface has the physical link down and the logical interface is down also.



Displaying the Status of a Specific SONET Interface

Purpose

To display the status of a specific SONET interface when you need to investigate its status further, use the following Junos OS CLI operational mode command:

Action

user@host> show interfaces so-fpc/pic/port

Sample Output 1

The following sample output is for an interface with the physical link down:

Sample Output 2

The following output is for an interface with the physical layer up and the link layer down:

Meaning

In the first sample output, the first line of the sample output shows that the physical link is down. This means that the physical link is unhealthy and cannot pass packets. Further down the sample output, look for active alarms and defects. When you see this situation, to further diagnose the problem, see Displaying Extensive Status Information for a Specific SONET Interface to display more extensive information about the SONET interface and the physical interface that is down.

In the second sample output, the sample output shows that the link layer is down. This means that the logical interface is not established end to end. When you see this situation, to further diagnose the problem, see Monitoring Statistics for a SONET Interface to monitor statistics for the SONET interface and the logical interface that is down.



Displaying Extensive Status Information for a Specific SONET Interface

Purpose

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

Action

user@host> show interfaces so-fpc/pic/port extensive

Sample Output

user@router> show interfaces so-1/1/1 extensive

Meaning

The sample output details where the errors might be occurring. Error details include input and output errors, active alarms and defects, and media-specific errors. The SONET section, line, and path errors help narrow down the source of the problem.

If the physical link is down, look at the active alarms and defects for the SONET interface and troubleshoot the SONET media accordingly. SeeList of Common SONET Alarms and Errors for an explanation of SONET alarms.

Monitoring Statistics for a SONET Interface

Purpose

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

Action

user@host> monitor interface so-fpc/pic/port

Caution

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.

Sample Output

user@router> monitor interface so-1/1/1

Meaning

This output checks for and displays common interface failures, whether or not loopback is detected, and any increases in framing errors. Information from this command can help you 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.

The statistics in the second column are the cumulative statistics since the last time they were cleared using the clear interfaces statistics interface-name command. The statistics in the third column are the statistics since the monitor interface interface-name command was executed.

If the framing errors are increasing, verify that the frame check sequence (FCS) and scrambling configuration match on both ends of the connection. If the configuration is correct, check the cabling to the router and have the carrier verify the integrity of the line.

If the input errors are increasing, check the cabling to the router and have the carrier verify the integrity of the line.

If you are sending output keepalives but are not receiving any input keepalives, verify that the encapsulation and keepalive configurations match on both ends of the connection.

Table 3 lists and describes the SONET error statistics in the output for the monitor interface command. The output fields are listed in the order in which they appear in the output.

Table 3: SONET Error Statistics

Output Field

Output Field Description

Input errors

Sum of the incoming frame aborts and FCS errors.

Input drops

Number of packets dropped by the output queue of the I/O Manager ASIC. If the interface is saturated, this number increments once for every packet that is dropped by the ASIC’s random early detection (RED) mechanism.

Input framing errors

The number of packets that have FCS errors.

Policed discards

Frames that the incoming packet match code discarded because they were not recognized or of interest. Usually, this field reports protocols that the Junos OS does not handle.

L3 incompletes

Increments when the incoming packet fails Layer 3 (usually IPv4) sanity checks of the header. For example, a frame with less than 20 bytes of available IP header would be discarded and this counter would increment.

L2 channel errors

Increments when the software cannot find a valid logical interface for an incoming frame.

L2 mismatch timeouts

Count of malformed or short packets that cause the incoming packet handler to discard the frame as unreadable.

Carrier transitions

Number of times the interface has gone from down to up. This number should not increment quickly, increasing only when the cable is unplugged, the far-end system is powered down and up, or a similar problem occurs. If it increments quickly (perhaps once every 10 seconds), then the cable, the far-end system, or the PIC is broken.

Output errors

Sum of the outgoing frame aborts and FCS errors. Because output errors are rare, hardware problems, configuration, or software bugs might contribute to the cause of them. Use the output of the show interfaces type-fpc/pic/port extensive command for more details about which output errors are incrementing. Also, analyze the system or interface load to determine if those areas are contributing to the cause of the problem. If the problem persists, open a case with the Juniper Networks Technical Assistance Center (JTAC) at support@juniper.net or at 1-888-314-JTAC (within the United States) or 1-408-745-9500 (from outside the United States).

Output drops

Number of packets dropped by the output queue of the I/O Manager ASIC. If the interface is saturated, this number increments once for every packet that is dropped by the ASIC’s RED mechanism.

Verifying the Status of the Logical Interface

Purpose

To verify the status of the logical interface, use the following two Junos OS CLI operational mode commands:

Action



user@host> show interfaces so-fpc/pic/port

user@host> show interfaces so-fpc/pic/port terse

Sample Output 1

The following sample output displays the information for a logical interface that is up:

Sample Output 2

The following sample output displays the information for a logical interface that is down:

Meaning

In the sample output 1, the show interfaces command in sample output 1 shows that the logical link is up because there are no flags indicating that the link layer is down. The output for the show interfaces terse command shows that logical interface so-2/2/0.0 is up.

Both commands in sample output 2 show that the logical interface is down. The first command shows that the link layer, device, and destination route are all down. The second command shows that logical interface so-2/2/0.0 is down.