Monday, August 15, 2011

Configuring Stack Power, what they DON'T tell you

Hi Guys

So their is a guide to configuring Stack Power for 3750x's available at:
http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_58_se/configuration/guide/swstkpwr.html#wp1015591

However, to say it is incomplete would be an understatement. If you just read this document, it appears all you have to do is plug the power cables in and away it goes, this however is not accurate, and sometimes it can be a little flakely, so without further ado, please enjoy my guide on getting stack power configured:

Step 1.
Get all your switches powered up using their own power, stack them together as a data stack, The directions change a little bit if your not using a stack OR if you don't have enough power cables and want to just get a few switches up using only one power cable, Your directions are a little diffirent. Leave a comment if you need help.



Step 2.
So, first of all you need to issue a command like such:


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

If you look at this output, the key words are Port 1 Status: Shut and Port 2 Status: Shut

This means that the stack power is not turned on yet on those ports, to turn it on issue this command:


switch1#stack-power switch 1 port 1 enable
switch1#stack-power switch 1 port 2 enable

This will enable stack power across the ports, you need to do this on every switch in your stack, so for example:

switch1#stack-power switch 2 port 1 enable
switch1#stack-power switch 2 port 2 enable

and so on and so forth for each switch, now you should also ensure all your switches are part of the same Power Stack (each switch can belong to one power stack group)

#show stack-power

Power stack name: Powerstack-1

Stack mode: Power sharing strict
Stack topology: Ring
Switch 1:
Power budget: 343
Low port priority value: 21
High port priority value: 12
Switch priority value: 3
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca71.1c00
Neighbor on port 2: 44d3.ca70.0e00

Switch 2:
Power budget: 373
Low port priority value: 20
High port priority value: 11
Switch priority value: 2
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca71.1b80
Neighbor on port 2: 44d3.ca71.1c00

Switch 3:
Power budget: 343
Low port priority value: 22
High port priority value: 13
Switch priority value: 4
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca70.0e00
Neighbor on port 2: 44d3.ca71.1b80



the configuration to place them all in the same group like this is shown below:

stack-power stack Powerstack-1

stack-power switch 1
stack Powerstack-1
stack-power switch 2
stack Powerstack-1
stack-power switch 3
stack Powerstack-1

This will place all three switches into the same power stack.

Now finally, the next step is to configure any parameters we might want such as setting one switch to have a higher priority than the other.

So, every switch has a priority, the higher priority switches have there power shedded first (confusing i know)

within the switch, there are also high-priority POE ports and low-priority POE Ports, you set your high priority POE ports with a lower value and your low-priority ports with a higher value

Note that a switches priority must be LOWER than its own ports, you could also use these values to make it so that, lets say you had three switches, you could say if you need to shed power, shed power from the low-priority POE ports for switch 1 and 2 first, THEN if still not enough power just shut down switch 3, then if still not enough power shut down switch 2 then 1

so you can see you can really ensure that each switch has a particular priority and same for the ports

Here is an example



switch#show stack-power
Power stack name: Powerstack-1
Stack mode: Power sharing strict
Stack topology: Ring
Switch 1:
Power budget: 343
Low port priority value: 11
High port priority value: 10
Switch priority value: 1
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca71.1c00
Neighbor on port 2: 44d3.ca70.0e00

Switch 3:
Power budget: 343
Low port priority value: 15
High port priority value: 14
Switch priority value: 3
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca70.0e00
Neighbor on port 2: 44d3.ca71.1b80

Switch 2:
Power budget: 373
Low port priority value: 13
High port priority value: 12
Switch priority value: 2
Port 1 status: Connected
Port 2 status: Connected
Neighbor on port 1: 44d3.ca71.1b80
Neighbor on port 2: 44d3.ca71.1c00

In this example, low priority ports on switch 3 are shed first, then the high priority ports

then on switch 2, low priority ports are shed first, then high priority

then on switch 1, low priority ports are shed first, then high priority

Finally, if enough power is not available with all POE ports turned off, switch 3 is turned off first, followed by switch 2, then switch 1


However, in the example above we have enough power to power all three switches with one power supply

25 comments:

  1. While the docs are not explicit, and it is somewhat assumed, but can you hot swap switches to the Stack Power? Going by your article here, it would seem so, but again nothing I have read says that is the case.

    Thanks!

    ReplyDelete
  2. Hi Peter,
    Thank you for putting together this article, it is great !! I do have a question though, when you refere to high priority ports and low priority ports once the metric is defined, it is also required to tell the switch which ports are high and low priority. i.e. i like to haver gi1/0/1 on high and don't care about g1/0/24 (low priority)...? is there a command for this at the interface level...?

    regards,

    Ivan V

    ReplyDelete
  3. Nice article. I'm getting the following error on my 3750 stack and have removed all stack power cables.

    %PLATFORM_STACKPOWER-4-REDUNDANCY_LOSS: Switch 3's power stack lost redundancy and is now operating in power sharing mode

    How can I remove this error. Again, there is no stack power cable in the physical set up.
    I've tried disabling the powerstack ports (1,2) but it didn't help.

    Thanks,
    Charlie

    ReplyDelete
  4. I should clarify that I do not want stack power configured. Just need the error to go away.

    thanks,
    Charlie

    ReplyDelete
  5. @Ivan
    interface gigabitetherent1/0/1
    power inline port priority high
    interface gigabitetherent1/0/24
    power inline port priority low

    @Charlie
    may be if you tray:
    stack-power switch 1
    standalone

    BR,
    Goose

    ReplyDelete
  6. what happens when the two switches in a stack has same power priorities?
    would that effect? or will it work in a similar way?

    ReplyDelete
  7. What happens when you pull out all the cables and a nuclear explosion goes off?

    ReplyDelete
  8. I am having a problem here, I can't see all the switches in the same power stack. ho I can do that.
    below error showing when issue the commands:
    " stack-power stack Powerstack-1
    stack-power switch 1
    stack Powerstack-1
    stack-power switch 2
    stack Powerstack-1
    "

    please advise

    ReplyDelete
  9. the error showing is"

    %Switch 2 is neither present nor provisioned in the stack

    the output of the show stack-power is below:

    show stack-power
    Power stack name: Powerstack-1
    Stack mode: Power sharing
    Stack topology: Ring
    Switch 1:
    Power budget: 190
    Low port priority value: 21
    High port priority value: 12
    Switch priority value: 2
    Port 1 status: Connected
    Port 2 status: Connected
    Neighbor on port 1: 24e9.b384.ec00
    Neighbor on port 2: 24e9.b384.ec00

    ReplyDelete
  10. How to cable two switches?

    ReplyDelete
  11. What is the correct way to cable two switches with stackpower cables. One cable stack one to stack one. Or one cable stack one to stack two. Or two cables stack one to stack one. And stack two to stack two. Or two cables stack one to stack two and stack two to stack one. And what is the difference if there are several correct options.

    ReplyDelete
  12. Another sound like very good allocation about Configuring Stack Power and hopefully whatever you have shared here seems to me very outstanding and I would like to know more about such input. Thanks dude :)

    ReplyDelete
  13. I've been getting the PLATFORM_STACKPOWER-4-REDUNDANCY_LOSS alerts forever. Looks like even if you don't use stackpower, your switch stack is configured for stackpower. Each switch is basically in its powerstack group with a unique power stack name. The only way to turn off that annoying alert is to do a show stack-power detail, and see which switch is running in redundant mode, then change the stack mode on that powerstack group.

    show stack-power detail
    Power Stack Stack Stack Total Rsvd Alloc Unused Num Num
    Name Mode Topolgy Pwr(W) Pwr(W) Pwr(W) Pwr(W) SW PS
    -------------------- ------ ------- ------ ------ ------ ------ --- ---
    Powerstack-1 SP-R Stndaln 350 160 190 0 1 1
    Powerstack-11 SP-PS Stndaln 350 160 190 0 1 1
    Powerstack-3 SP-PS Stndaln 350 160 190 0 1 1

    Power stack name: Powerstack-1
    Stack mode: Redundant
    Stack topology: Standalone
    Switch 2:
    Power budget: 190
    Power allocated: 190
    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

    Power stack name: Powerstack-11
    Stack mode: Power sharing
    Stack topology: Standalone
    Switch 1:
    Power budget: 190
    Power allocated: 190
    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

    Power stack name: Powerstack-3
    Stack mode: Power sharing
    Stack topology: Standalone
    Switch 3:
    Power budget: 190
    Power allocated: 190
    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

    (config)#stack-power stack Powerstack-1
    (config-stackpower)#mode ?
    power-shared Power shared mode
    redundant Redundant mode

    show stack-power
    Power Stack Stack Stack Total Rsvd Alloc Unused Num Num
    Name Mode Topolgy Pwr(W) Pwr(W) Pwr(W) Pwr(W) SW PS
    -------------------- ------ ------- ------ ------ ------ ------ --- ---
    Powerstack-1 SP-PS Stndaln 350 160 190 0 1 1
    Powerstack-11 SP-PS Stndaln 350 160 190 0 1 1
    Powerstack-3 SP-PS Stndaln 350 160 190 0 1 1

    ReplyDelete
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  21. Thank you for posting this information! We named the powerstack as [Site_VLAN#]; however, the show stack-power output still references the default Powerstack-1 name. Can this be configured to match the custom name? Also, when viewing the output on a stack with a standalone and a stack, the standalone shows up as Powerstack-11. How are the powerstacks numbered by the system and why does a named power stack still show up as the default name? Can you help, please?

    ReplyDelete
    Replies
    1. I can help you.but I don't know if power stack use power cord

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