Related Documentation
- M, T Series
- List of Common SONET Alarms and Errors
- Displaying SONET Alarms and Errors
- Locating Most Common SONET Alarms and Errors
- Locating Loss of Signal Alarms
- Locating Alarm Indication Signal Alarms
- Locating Remote Defect Indication Alarms
- Locating Remote Error Indication Line Errors
- Locating Bit Error Rate Alarms
- Locating Payload Label Mismatch Path Alarms
- Locating Loss of Pointer Path Alarms
- Locating Unequipped Payload Alarms
Locating Phase Lock Loop Alarms
Problem
The phase lock loop (PLL) alarm occurs when the PLL cannot lock on to a timing device, and indicates a possible hardware or network timing problem.
Solution
To display SONET alarms and errors, use the following Junos OS CLI operational mode command:
Sample Output
user@host> show interfaces so-1/1/1 extensive [...Output truncated...]
Active alarms : PLL
Active defects : PLL
SONET PHY: Seconds Count State
PLL Lock 26 0 PLL Lock Error
PHY Light 0 0 OK
SONET section:
BIP-B1 0 0
SEF 0 0 OK
LOS 0 0 OK
LOF 0 0 OK
ES-S 0
SES-S 0
SEFS-S 0
SONET line:
BIP-B2 0 0
REI-L 0 0
RDI-L 3 3 OK
AIS-L 0 0 OK
BERR-SF 0 0 OK
BERR-SD 0 0 OK
ES-L 0
SES-L 0
UAS-L 0
ES-LFE 0
SES-LFE 0
UAS-LFE 0
SONET path:
BIP-B3 0 0
REI-P 0 0
LOP-P 0 0 OK
AIS-P 0 0 OK
RDI-P 0 0 OK
UNEQ-P 0 0 OK
PLM-P 0 0 OK
ES-P 0
SES-P 0
UAS-P 0
ES-PFE 0
SES-PFE 0
UAS-PFE 0
[...Output truncated...]
Meaning
The sample output shows a PLL alarm lasting for 26 seconds. You must investigate the timing source to diagnose the problem. The timing source is derived from an incoming SONET circuit (when clock external is configured), or from the onboard Stratum 3 clock (when clock internal is configured). Internal clocking is the default for Juniper Networks routers.
The cause of the problem differs depending on the type of system board on the router. (See Table 1.) For example:
- On the M20 and M40 Internet router OC48-SM-IR PIC and the M160 Internet router OC192 board, the problem might be caused by the following:
- An out-of-tolerance clock coming from the far end, if clocking external is configured.
- An out-of-tolerance clock coming from the far end or a problem with the board being unable to lock on to its internal clock to derive the transmit clock, if clocking internal is configured.
- On OC3 and OC12 PICs, the PIC not establishing a lock to the onboard clock to derive the outgoing clock.
To further diagnose the problem, try the following:
- Configure clocking to external. If the alarm disappears, the board might not have locked to the internal clock used to derive the outgoing clock.
- Configure clocking to internal and make sure that a loopback fiber is plugged in. If the PLL alarm persists, it is most likely a hardware problem. However, you may not be able to determine if the direction is on the inbound or outbound side of the board.
Table 1 shows the location of the onboard clock on the various system boards of Juniper Networks routers.
Table 1: Location of the Onboard Clock
Router | System Board |
|---|---|
M5, M10, M20, and M40 routers | System Control Board (SCB), System and Switch Board (SSB), Switching and Forwarding Module (SFM), and Single Board Router (SBR) |
OC48-SM-IR PIC used on the M20 and M40 routers | Flexible PIC Concentrator (FPC) |
M40e and M160 routers | Miscellaneous Control Subsystem (MCS) |
T-series routing platforms | SONET Clock Generator (SCG) |
Related Documentation
- M, T Series
- List of Common SONET Alarms and Errors
- Displaying SONET Alarms and Errors
- Locating Most Common SONET Alarms and Errors
- Locating Loss of Signal Alarms
- Locating Alarm Indication Signal Alarms
- Locating Remote Defect Indication Alarms
- Locating Remote Error Indication Line Errors
- Locating Bit Error Rate Alarms
- Locating Payload Label Mismatch Path Alarms
- Locating Loss of Pointer Path Alarms
- Locating Unequipped Payload Alarms
Published: 2012-12-10
Related Documentation
- M, T Series
- List of Common SONET Alarms and Errors
- Displaying SONET Alarms and Errors
- Locating Most Common SONET Alarms and Errors
- Locating Loss of Signal Alarms
- Locating Alarm Indication Signal Alarms
- Locating Remote Defect Indication Alarms
- Locating Remote Error Indication Line Errors
- Locating Bit Error Rate Alarms
- Locating Payload Label Mismatch Path Alarms
- Locating Loss of Pointer Path Alarms
- Locating Unequipped Payload Alarms
