Configuring Slow Packet Forwarding Engine Alarm
On an M Series, an MX Series, or a T Series router, the Packet Forwarding Engine might not send a resource acknowledgment message to the Routing Engine within a predetermined time of 360 seconds. This delay in receiving resource acknowledgment could be due to a slow or stuck Packet Forwarding Engine on the M Series, MX Series, or T Series router, or on one of the LCCs connected to a TX Matrix, TX Matrix Plus, or TX Matrix Plus router with 3D SIBs.
Starting with Junos OS Release 13.2R1 (also applicable in Junos OS Releases 12.1R6, 12.2R5, 12.3R3, 13.1R2 and later), to display the issue as an alarm in the show chassis alarms command output and to append the alarm to the system log messages file, you must enable the slow Packet Forwarding Engine alarm on the router.
The following sections provide more information about the slow Packet Forwarding Engine alarm:
- Enabling Slow Packet Forwarding Engine Alarm
- Disabling Slow Packet Forwarding Engine Alarm
- Verifying That the Alarm Output and System Log Messages Are Updated
Enabling Slow Packet Forwarding Engine Alarm
To enable the slow Packet Forwarding Engine alarm, perform the following steps:
 | Note: By default, the slow Packet Forwarding Engine alarm is disabled. |
- In configuration mode, go to the [edit chassis] hierarchy level:[edit]user@host# edit chassis
- Enable the slow Packet Forwarding Engine alarm by configuring
the slow-pfe-alarm statement.[edit chassis]user@host# set slow-pfe-alarm
Disabling Slow Packet Forwarding Engine Alarm
To disable the slow Packet Forwarding Engine alarm, perform the following steps:
- In configuration mode, go to the [edit chassis] hierarchy level:[edit]user@host# edit chassis
- Disable the slow Packet Forwarding Engine alarm by deleting
the slow-pfe-alarm statement.[edit chassis]user@host# delete slow-pfe-alarm
Verifying That the Alarm Output and System Log Messages Are Updated
Purpose
To verify that the output of the show chassis alarms operational mode command and the system log messages file are updated with the slow Packet Forwarding Engine alarm when:
- The slow-pfe-alarm statement is enabled in the [edit chassis] hierarchy.
- The Packet Forwarding Engine resource acknowledgment is not received by the Routing Engine within a predetermined time of 360 seconds.
Action
To check the output on an M Series, MX Series, or a T Series router:
- Verify that the alarm is displayed in the output of the show chassis alarms operational mode command.
show chassis alarms
user@host> show chassis alarms1 alarms currently active Alarm time Class Description 2013-02-05 01:12:33 PST Minor Potential slow peers are: XDPC2
For field descriptions, see show chassis alarms.
- Verify that the alarm is appended to the system log messages
file.
/var/log/messages – ... Alarm set: RE color=YELLOW, class=CHASSIS, reason=Potential slow peers are: XDPC2 ... Minor alarm set, Potential slow peers are: XDPC2
To check the output on a TX Matrix, TX Matrix Plus, or a TX Matrix Plus with 3D SIBs router:
- Verify that the alarm is displayed in the output of the show chassis alarms operational mode command.
show chassis alarms
user@scc> show chassis alarmsscc-re0: -------------------------------------------------------------------------- 9 alarms currently active Alarm time Class Description 2013-02-06 00:45:46 PST Minor Potential slow peers are: LCC1 LCC0 ... lcc0-re0: -------------------------------------------------------------------------- 4 alarms currently active Alarm time Class Description 2013-02-06 00:44:51 PST Minor Potential slow peers are: GFPC4 GFPC3 ... lcc1-re0: -------------------------------------------------------------------------- 4 alarms currently active Alarm time Class Description 2013-02-06 00:45:44 PST Minor Potential slow peers are: GFPC10 ... lcc2-re0: -------------------------------------------------------------------------- No alarms currently active lcc3-re0: -------------------------------------------------------------------------- No alarms currently active
For field descriptions, see show chassis alarms.
- Verify that the alarm is appended to the system log messages
file.
... Alarm set: RE color=YELLOW, class=CHASSIS, reason=Potential slow peers are: LCC0 LCC1 ... Minor alarm set, Potential slow peers are: LCC0 ... Alarm set: RE color=YELLOW, class=CHASSIS, reason=Potential slow peers are: GFPC4 GFPC3 ... Minor alarm set, Potential slow peers are: GFPC4 GFPC3 ... Alarm set: RE color=YELLOW, class=CHASSIS, reason=Potential slow peers are: GFPC10 ... Minor alarm set, Potential slow peers are: GFPC10
Meaning
The output of show chassis alarms operational mode command and the system log messages file are updated as expected when the slow Packet Forwarding Engine alarm is enabled and when the Packet Forwarding Engine resource acknowledgment is not received by the Routing engine within a predetermined time of 360 seconds.
