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Troubleshooting tips for 3750X Stack power feature

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Introduction

Cisco Stackpower technology is a new feature introduced in the Cisco catalyst 3750-X series switches that aggregates all of the available power in a stack of switches and manages it as one common power tool.

The catalyst 3750X has two power supplies per system which allows the power load to be split between them. This system increases the maximum power per port to 30 Watts to meet the POE+ standard (802.3at). Wih POE+, a 48 port system would need 1440 Watts to provide 30 Watts per port per powered device. Systems with few powered devices might require only one Power Supply in which case second Power Supply can provide one-to-one redundancy for active Power Supply.

A power stack can not contain more than four switches and Power Supplies of these switches can be managed as one large Power Supply that provides power to all switches. In this way, any faulty Power Supply in a single switch can be replaced without taking that switch offline.

Stack Power also allows deployment of expandable Power System, XPS 2200 to create large power pools. This system forms a star topology which shares power with up to 9 switches and provides improved reliability, availability and efficiency.

See Stack Power in action video which demonstrates the Stack Power feature of catalyst 3750X switches. 

Requirements

There are no specific requirements.

Troubleshooting tips

One of the most common issue seen with Stack Power feature is that even when the switches are in stack, the stack topology is still standalone which means that the power sharing feature has not started yet. The commands used to see this issue and correct it are:

show stack-power is the command which is used to check whether the feature has started or not. When we don't have any issues, the output would be something like:

Switch# show stack-power
Power stack name: Powerstack1
Stack mode: Power sharing
Switch 1:
Power budget: 206
Low port priority value: 17
High port priority value: 16
Switch priority value: 2
Port A status: Not shut
Port B status: Not shut
Neighbor on port A: 0022.bdcf.ab00
Neighbor on port B: 0022.bdd0.4380

 

And, in cases when we don't have this feature started yet we will see something like:

Switch# show stack-power
Power stack name: Powerstack-1
Stack mode: Power sharing strict
Stack topology: Standalone
Switch 3:
Power budget: 1063
Low port priority value: 22
High port priority value: 13
Switch priority value: 4
Port 1 status: Shut
Port 2 status: Shut
Neighbor on port 1: 0000.0000.0000
Neighbor on port 2: 0000.0000.0000

 

These ports 1 and 2 are power ports and should be enabled for use of power sharing feature. These ports can be enabled by using following command in EXEC mode:

switch#stack-power switch 3 port 1 enable

switch#stack-power switch 3 port 2 enable

Please note that these commands are to be issued in EXEC mode. One very common mistake is to type these commands in global configuration mode.

%PLATFORM_STACKPOWER-4-UNDER_BUDGET:

This message is observed even when the power supplies looks OK otherwise.This message is also observed in cases when we have just got the power feature started by enabling power ports.

There are few options available to overcome this issue:

1. .Power cycle not reload the switch which is issuing these messages (like switch 2 in above error message)

2.  Put the particular switch or all the switches in stack in standalone mode, this can be done by issuing following command:

Switch(config)#stack-power switch 
Switch(config-switch-stackpower)#standalone

Once this is done, wait for 60-90 seconds and see if the error message goes away. Once the error message ceases, put the switch/switches out of standalone mode by using "no standalone" command.

%PLATFORM_STACKPOWER-4-PRIO_CONFLICT:

There is no specific troubleshooting for this issue however, certain guidelines can be followed to avoid such situations:

You can configure priority of a switch and of a powered device. This priority determines which switch/port will shut down first in case of power shortage. You can configure three priorities per system (switch):

1. The system (switch) priority.

2. Priority of high priority POE ports.

3. Priority of low priority POE ports.

On any switch, the switch priority should be lower than the priority of POE ports and the high priority values must be set lower than the low priority values. It is recommended that you configure different priority values for each switch and its high priority and low priority ports. This limits the number of devices shut down at a time during loss of power. If you try to configure same priority values at different switches, the configuration will be allowed but you will receive an error message.

The default priority ranges, if none are configured, are 1-9 for switches, 10-18 for high-priority ports, and 19-27 for low-priority ports.

Troubleshooting examples

Example 1:

Problem Description:

After configuring stack “mode redundant”, power redundancy through stack-wise not working

Symptoms:

An Error Message:

%PLATFORM_STACKPOWER-4-REDUNDANCY_LOSS: Switch 2's power stack lost redundancy and is now operating in power sharing

mode

Switch3750-X#show stack-power
Power stack name: Powerstack1
Stack mode: Redundant
Stack topology: Standalone
Switch 2:
Power budget: 1663
Low port priority value: 22
High port priority value: 13
Switch priority value: 4
Port 1 status: Shut
Port 2 status: Connected
Neighbor on port 1: 0000.0000.0000
Neighbor on port 2: f866.f25a.7d00

 

Output of the command “show stack power” shows the port status as “Shut”

Output of the command "show environment power"

Switch3750-X#sho env power

SW     PID                                       Serial#             Status           Sys Pwr    PoE    PwrWatts
-----    -------                                   --------------         ---------------   --------------- ------   --------------
1A    C3KX-PWR-715WAC        AAAAAAAA0F4       OK              Good     Good      715/0
1B    Not Present

 

Troubleshooting Steps

  1. Redundancy is configured however the power stack ports are shut
  2. Enable all power stack ports by command “stack-power switch [number] port [number] enable”

Switch3750-X#stack-power switch 2 port 1 enable

Example 2:

Problem Description:

Getting the following error message on a 3750X switch stack.

%PLATFORM_STACKPOWER-4-PRIO_CONFLICT: Switch 3's power stack has conflicting power priorities
Lets see at the output of show stack-power
Power stack name: Powerstack-1
Stack mode: Power sharing
Switch 1:
Power budget: 1646
Low port priority value: 22                                                  
High port priority value: 13
Switch priority value: 3
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: c84c.75b7.4300                                              
Neighbor on port 2: 5475.d096.cc00                                              Switch 2:
Power budget: 1646
Low port priority value: 22                
High port priority value: 13
Switch priority value: 5
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 5475.d096.cc00
Neighbor on port 2: 5475.d071.ea80
Switch 3:
Power budget: 1646
Low port priority value: 21
High port priority value: 12
Switch priority value: 4
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: c84c.75b7.4300
Neighbor on port 2: 5475.d071.ea80
The output above shows that the switch 1 and 2 are configured with same priorities.


Troubleshooting Steps:

 Change the switch 1/2 high & low priority value to some other number and do a "wr mem" in the privilege mode.
For example:

Conf t
Switch(config)#Stack-power switch 2
Power-priority high 11
Power-priority low 23Switch(config)#Exit 
Switch#wr mem

 

Related Information

Comments
Cisco Employee

Nice document to understand stack power feature and good troubleshooting tips.

Cisco Employee

Thanks for lliking it!

Regards,

Pulkit

Beginner

Excellent ,

%PLATFORM_STACKPOWER-4-UNDER_BUDGET: solved my issue

Beginner

Nice article!

Beginner

Hi

I have a stack switch with 8 switches 3750 and one of stack member be restarted!

this happen several times

what is reason this problem?

Community Member

Very useful also for 3850s.

%PLATFORM_STACKPOWER-4-REDUNDANCY_LOSS: Switch 2's power stack lost redundancy and is now operating in power sharing - Solved my issue

Beginner

I have a 3 3750X switches that I am trying to get StackPower to work.  I am not able to run any stack-power commands, like "stack-power switch ____" or "show stack-power".  It isn't in IOS help either.  The article says that there are no requirements for this, but has anyone else had this issue?  Am I missing something?  Thanks.

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