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[EX] New PoE interfaces go down when more than 4 PoE+ devices are connected with lldp power negotiation enabled

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Article ID: KB35604 KB Last Updated: 02 Apr 2020Version: 1.0
Summary:

Newly added PoE ports are going down after connecting more than 4 PoE+ devices in a EX2300-C with Link Layer Discovery Protocol (LLDP) power negotiation enabled.

Symptoms:

This scenario has default configuration on the switch, PoE power management set to class, and lldp/lldp-med enabled on all interfaces.

The user connected 6 PoE+ devices to EX2300-C and there are plenty of power budge but the interface ge-0/0/9 and ge-0/0/10 which connected to PoE+ devices are down. The error on port is shown below:

user@router > show poe interface
Interface    Admin       Oper    Pair/Mode  Max        Priority       Power          Class
             status      status  status     power                     consumption
 ge-0/0/0    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/1    Enabled      ON     2P/AT      25.5W(L)   Low            8.4W            4
 ge-0/0/2    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/3    Enabled      ON     2P/AT      25.5W(L)   Low            8.2W            4
 ge-0/0/4    Disabled    Disabled 2P/AT     0.0W       Low            0.0W           not-applicable
 ge-0/0/5    Enabled      ON     2P/AT      25.5W(L)   Low            8.4W            4
 ge-0/0/6    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/7    Enabled      ON     2P/AT      25.5W(L)   Low            8.6W            4
 ge-0/0/8    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/9    Enabled     OFF     2P/AT      30.0W      Low            0.0W           not-applicable <-- This interface is OFF
 ge-0/0/10    Enabled     OFF     2P/AT      15.4W      Low            0.0W          not-applicable <-- This interface is OFF

 ge-0/0/11    Enabled     OFF     2P/AT      15.4W      Low            0.0W          not-applicable

  
{master:0}
user@router > show poe interface ge-0/0/9
PoE interface status:
PoE interface                :  ge-0/0/9
Administrative status        : Enabled
Operational status           :  OFF
Operational status detail    : Static Mode Exceeded Power Limit <-- Error
FourPair status              : Disabled
Power limit on the interface : 30.0W
Priority                     : Low
Power consumed               : 0.0W
Class of power device        : not-applicable
PoE Mode                     :   802.3at
 
{master:0}
user@router > show poe interface ge-0/0/10
PoE interface status:
PoE interface                : ge-0/0/10
Administrative status        : Enabled
Operational status           :  OFF
Operational status detail    : Static Mode Exceeded Power Limit <-- Error
FourPair status              : Disabled
Power limit on the interface : 15.4W
Priority                     : Low
Power consumed               : 0.0W
Class of power device        : not-applicable
PoE Mode                     :   802.3at
 
user@router > show poe controller
Controller  Maximum   Power         Guard    Management   Status        Lldp
index       power     consumption   band                                Priority
   0        146W      33.80W          0W     Class        AT_MODE       Disabled
 
{master:0}
user@router > show chassis power-budget-statistics
fpc 0:
-------------------------------------------------------------------------
            PSU 0    (JPSU-170W-AC       )           :     170 W   Online
            Power redundancy configuration           :     N+0
            Total power supplied by all online PSUs  :     170 W
            Base power reserved                      :      24 W
            Total power allocated for PoE            :     146 W
            Total PoE power consumed                 :      33 W
            Total PoE power remaining                :     113 W

 

Rebooting the switch does not resolve the issue. The port would turn on briefly after the switch reboot, but it goes down again.

Cause:

On the EX2300-C-12P platform, the PoE ports are going down after the total PoE consumed power exceeds 124W but not reaching the maximum power 146W. The issue results in the PoE device going down.

Solution:

The maximum PoE power for Platform EX2300-C-12P is 124W, not 146W. Refer to the technical documentation on Power over Ethernet (PoE) Ports.

As per the maximum PoE power value, this behavior is expected. The PoE max value in the output of 'show poe controller' and 'show chassis power-budget-statistics' will to be updated to 124W instead of 146W on fixed version.

This issue is resolved in the following Junos OS releases:

  • Junos:18.1R3-S10
  • Junos:18.2R3-S3
  • Junos:18.3R3-S2
  • Junos:19.2R2
  • Junos:19.3R3
  • Junos:19.4R2
  • Junos:20.1R2
  • Junos:20.2R1

Workaround:

Disable the power-negotiation for lldp using the below command:

set protocol lldp interface all power-negotiation disable

 When LLDP power negotiation is disabled:

user@router > show poe interface
Interface    Admin       Oper    Pair/Mode  Max        Priority       Power          Class
             status      status  status     power                     consumption
 ge-0/0/0    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/1    Enabled      ON     2P/AT      30.0W      Low            7.8W            4
 ge-0/0/2    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/3    Enabled      ON     2P/AT      30.0W      Low            5.8W            4
 ge-0/0/4    Disabled    Disabled 2P/AT     0.0W       Low            0.0W           not-applicable
 ge-0/0/5    Enabled      ON     2P/AT      30.0W      Low            5.6W            4
 ge-0/0/6    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/7    Enabled      ON     2P/AT      30.0W      Low            5.6W            4
 ge-0/0/8    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable
 ge-0/0/9    Enabled      ON     2P/AT      25.5W(L)   Low            4.6W            4  <-- This interface is UP
 ge-0/0/10    Enabled     ON     2P/AT      15.4W      Low            2.2W            3  <-- This interface is UP
 ge-0/0/11    Enabled     OFF     2P/AT      15.4W      Low            0.0W           not-applicable

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