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.
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-powerPower stack name: Powerstack1Stack mode: Power sharingSwitch 1:Power budget: 206Low port priority value: 17High port priority value: 16Switch priority value: 2Port A status: Not shutPort B status: Not shutNeighbor on port A: 0022.bdcf.ab00Neighbor 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-powerPower stack name: Powerstack-1Stack mode: Power sharing strictStack topology: StandaloneSwitch 3:Power budget: 1063Low port priority value: 22High port priority value: 13Switch priority value: 4Port 1 status: ShutPort 2 status: ShutNeighbor on port 1: 0000.0000.0000Neighbor 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.
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:
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.
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.
After configuring stack “mode redundant”, power redundancy through stack-wise not working
An Error Message:
%PLATFORM_STACKPOWER-4-REDUNDANCY_LOSS: Switch 2's power stack lost redundancy and is now operating in power sharing
Switch3750-X#show stack-powerPower stack name: Powerstack1Stack mode: RedundantStack topology: StandaloneSwitch 2:Power budget: 1663Low port priority value: 22High port priority value: 13Switch priority value: 4Port 1 status: ShutPort 2 status: ConnectedNeighbor on port 1: 0000.0000.0000Neighbor 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 powerSW PID Serial# Status Sys Pwr PoE PwrWatts----- ------- -------------- --------------- --------------- ------ --------------1A C3KX-PWR-715WAC AAAAAAAA0F4 OK Good Good 715/01B Not Present
Redundancy is configured however the power stack ports are shut
Enable all power stack ports by command “stack-power switch [number] port [number] enable”
Switch3750-X#stack-power switch 2 port 1 enable
Getting the following error message on a 3750X switch stack.
%PLATFORM_STACKPOWER-4-PRIO_CONFLICT: Switch 3's power stack has conflicting power prioritiesLets see at the output of show stack-powerPower stack name: Powerstack-1Stack mode: Power sharingSwitch 1:Power budget: 1646Low port priority value: 22 High port priority value: 13Switch priority value: 3Port 1 status: ConnectedPort 2 status: ConnectedNeighbor on port 1: c84c.75b7.4300 Neighbor on port 2: 5475.d096.cc00 Switch 2:Power budget: 1646Low port priority value: 22 High port priority value: 13Switch priority value: 5Port 1 status: ConnectedPort 2 status: ConnectedNeighbor on port 1: 5475.d096.cc00Neighbor on port 2: 5475.d071.ea80Switch 3:Power budget: 1646Low port priority value: 21High port priority value: 12Switch priority value: 4Port 1 status: ConnectedPort 2 status: ConnectedNeighbor on port 1: c84c.75b7.4300Neighbor on port 2: 5475.d071.ea80The output above shows that the switch 1 and 2 are configured with same priorities.
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 tSwitch(config)#Stack-power switch 2Power-priority high 11Power-priority low 23Switch(config)#ExitSwitch#wr mem
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