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How to Troubleshoot Cisco 3750X Stack

Power Feature?
Cisco Stackpower technology is a 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 Cisco 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.

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
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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
2

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:
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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
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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#
————–

1A C3KX-PWR-715WAC
5

Status Sys Pwr PoE PwrWatts
————— ————— —— ————–

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
Let’s 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
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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

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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 23
Switch(config)#Exit
Switch#wr mem

It refers from www.cisco.com
More related:
Cisco StackPower
Cisco Catalyst 3750-X Series Switches
How to Activate Cisco Catalyst 3750-X and 3560-X Series Products?
Cisco IOS Software for Cisco Catalyst 3750-X and 3560-X Series Switches
How to Select the Right Power Supply for Cisco Catalyst 3750-X Series Switch?
More Cisco products and Reviews you can visit: http://www.3anetwork.com/blog

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