Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

Locating ATM Alarms and Errors

 

List of Common ATM Alarms and Error

Purpose

To check Asynchronous Transfer Mode (ATM) alarms and errors on both ATM1 and ATM2 IQ interfaces.

Action

Table 1 provides links and commands for checking ATM alarms and errors.

Table 1: List of Common ATM Alarms and Error

Tasks

Command or Action

Displaying ATM1 and ATM2 Alarms and Errors

show interfaces at-fpc/pic/port extensive

See List of Common SONET Alarms and Errors.

See Checklist of Common T3 Alarms and Errors.

Displaying ATM1 and ATM2 Alarms and Errors

Purpose

The alarms and errors that appear on an ATM1 or an ATM2 IQ interface are identical. ATM alarms and errors are dependent on the ATM interface media. If the ATM interface is an OC3 or OC12 interface media, the media statistics are SONET statistics. If the ATM interface is a T3 interface media, the media statistics are T3 statistics.

For information on determining the type of ATM interface on your router, see Checklist for Determining ATM Interface Type.

Action

To display ATM alarms and errors, use the following Junos OS command-line interface (CLI) operational mode command:

Sample Output 1

user@host> show interfaces at-2/0/0 extensive

Meaning

Sample output 1 shows the error statistics for an OC3 ATM interface. SONET alarms and errors fall into three different areas of the output: section, line, and path. SeeList of Common SONET Alarms and Errors for information on SONET alarms.

Sample Output 2

user@host> show interfaces at-3/1/0 extensive

Meaning

Sample output 2 shows the error statistics for a T3 ATM interface. See Checklist of Common T3 Alarms and Errors for information on T3 alarms.

Table 2 describes the input and output errors that appear in the extensive output for an ATM interface.

Table 2: ATM Interface Input and Output Errors

Error

Description

Reason for Error

Input Errors

Errors

Sum of the incoming frame aborts and frame check sequence (FCS) errors.

 

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.

Invalid VCs

Number of cells that arrived for a nonexistent virtual circuit (VC).

 

Framing errors

Sum of ATM Adaptation Layer (AAL5) packets that have FCS errors, AAL5 packets that have reassembly timeout errors, and AAL5 packets that have length 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

Number of packets discarded due to the packets failing Layer 3 header checks.

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

Errors that occurred when the software could not find a valid logical interface for an incoming frame.

This counter increments when the software cannot find a valid logical interface for an incoming frame.

L2 mismatch timeouts

Count of malformed or short packets.

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

Output Errors

Carrier transitions

Number of times the interface went from down to up.

This number should not increment quickly and should increase 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 Physical Interface Card (PIC) is broken.

Errors

Sum of the outgoing frame aborts and FCS errors.

 

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.

Aged packets

Number of packets that remained in shared packet SDRAM for so long that the system automatically purged them.

The value in this field should never increment. If it does, it is most likely a software bug or possibly broken hardware.

Table 3 lists ATM media-specific alarms and defects that can render the interface unable to pass packets. When a defect persists for a certain amount of time, it is promoted to an alarm. Based on the router configuration, an alarm can ring the red or yellow alarm bell on the router or trigger the red or yellow alarm LED on the craft interface. For complete explanations of most of these alarms and defects, see Chapter 6 in GR-253, Synchronous Optical Network (SONET) Transport Systems: Common Generic Criteria.

Table 3: ATM Active Alarms and Defects

Alarm

Description

AIS

Alarm indication signal

AIS-L

Alarm indication signal (line)

AIS-P

Alarm indication signal (path)

BERR

Bit error rate

BERR-SD

Bit error rate defect–signal degrade

BERR-SF

Bit error rate fault–signal fail

EXZ

Excessive zeros

FERF

Far end receive failures

IDLE

Idle code detected

LCD

Loss of cell delineation

LCV

Line code violation

LOC

Loss of cell delineation

LOF

Loss of frame

LOL

Loss of light

LOP

Loss of pointer

LOS

Loss of signal

PLL

Phase-locked loop out of lock

PLCP_LOF

Loss of PLCP frame alarm

PLCP_YLW PLCP

Alarm at the remote end

PLM-P

Payload label mismatch

RDI

Remote defect indication

RDI-L

Remote defect indication (line)

RDI-P

Remote defect indication (path)

REI

Remote error indication

SEF

Severely errored frame

UNEQ

Unequipped

YLW

Remote defect indication (yellow alarm)