stackpower: stacked more than four switches

[jaheshkhan]

Today when I console  one of our client's stacked switch, i found the following logs generating:

*Feb 9 07:27:06.336: %PLATFORM_STACKPOWER-3-INVALID_TOPOLOGY: Invalid power stack topology observed by switch 2. More than four switches are connected in ring topology
*Feb 9 07:27:06.342: %PLATFORM_STACKPOWER-3-INVALID_TOPOLOGY: Invalid power stack topology observed by switch 1. More than four switches are connected in ring topology
*Feb 9 07:27:06.342: %PLATFORM_STACKPOWER-3-INVALID_TOPOLOGY: Invalid power stack topology observed by switch 4. More than four switches are connected in ring topology
*Feb 9 07:27:06.342: %PLATFORM_STACKPOWER-3-INVALID_TOPOLOGY: Invalid power stack topology observed by switch 3. More than four switches are connected in ring topology

What will happen if one switch powered off in this case?

I found five 9300-48 switches are data and power stacked. Ring topology is used. 

As per cisco document, only 4 switches must be used for Ring topology.

In that case, I want to change it.

Here are my concerns.

5 switches together will be data stacked

im now planning 3 switches will be stackpowered usingring topology and rest two switches separately powerstacked.

can we they co-exist together in this way? 

Are stackpower hotswappable? do I need to shutdown switches before rearranging the powerstack cables as mentioned above?

[balaji.bandi]

Switch can be stacking up to 8 (some says 9 - but never tested 9th one) - 8 is sure testing and working

Switch Stacking and Power Stacking Guidelines

Up to four switches can be configured in a StackPower stack using the StackPower connector at the rear of the switch. However, with XPS-2200, you can configure up to nine C9300 switches in a StackPower stack. Currently, C9300X switches do not support XPS-2200.

below guide help you how to stack and stack power cable. :

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9300/hardware/install/b_c9300_hig/b_c9300_hig_chapter_010.html

Persinally i will take maintenance window and re-arrange (to be safe , rather a sorry).

[jaheshkhan]

kindly note we cannot buy new XPS-2200 at the moment.

I was asking about with 5 switches what all changes I can do in this case?

hotswappable is possible or not?

maintenance downtime window required or not?

whether 5 data stack swithches and 3 powerstack and 2 powerstack can co exist or not?

[balaji.bandi]

Hope you have not read the document which have sent.

A switch power stack can include a maximum of four switches in a ring topology and nine switches in a star topology

I was asking about with 5 switches what all changes I can do in this case?  - adding to stack or stackpower ? stack power above answers your question.

hotswappable is possible or not?   -  Power stack cable  - i would advise always power of stack and connect.

maintenance downtime window required or not?  - yes my advise maintenance window required. (until you want to take chance)

whether 5 data stack swithches and 3 powerstack and 2 powerstack can co exist or not?   - Data stack can be up to 8, as per my testing only 4, you looking to have that single stack that option (i never tested) and i do not belive that work. since maximum is only 4 as i mentioned tested.

Hope that clarifies.

[jaheshkhan]

I have already read that document.

my question is that whether the same 5 datastacked switches can powerstacked  as 3 switches and 2 switches separately?

rest i understand powerstack we will do in the shutdown maintenance window. still I wish to know whether any other tried  to rearrange powerstack cable without shutdown ? i thinks this only cisco can answer. most of the end users will never take risk on this matter.

[Joseph W. Doherty]

I'm not current on 9K switch stacks, but on earlier series, data ring and stack ring, I recall (?), would work as you desire.  I.e. stack of 5 for data and stack of 3 and 2 for power.

Also on the earlier switches, some has a wattage limitation on the power cables (not well documented), i.e. you might not be able to power another switch via the the power cables.  This limitation also meant you had to be careful how you populated power supply modules, such that, failure of a single power supply unit could be supported by the power stack.

[jaheshkhan]

is powerstack hot swappable? do we need to shutdown whole switch ring to rearrange powerstack??

[Joseph W. Doherty]

"is powerstack hot swappable?"

Don't know for sure, but as a guess, I would suspect they are hot swapable.

"do we need to shutdown whole switch ring to rearrange powerstack??"

Again, don't know for sure. But if they are hot swapable, you shouldn't need to shut down the whole stack.

BTW, to your question to @balaji.bandi, i.e. "maintenance downtime window required or not?", even if not required (i.e. you can hot swap), any changes, especially like this one, should be performed when an unplanned outage would have the least impact.  That doesn't, though, always required a "scheduled downtime", just "scheduled maintenance"; not the same thing.

[Leonardo Pena Davila]

Hello   jaheshkhan, 

my question is that whether the same 5 datastacked switches can powerstacked  as 3 switches and 2 switches separately?

Yes, multiple power stacks are possible within a single StackWise stack.  For example, a StackWise data stack of eight switches can be configured into two StackPower stacks of four switches. Up to eight switches can be part of a power stack in star topology.

A Stackwise data stack of 6 switches can be configured into two StackPower of 4 and 2 switches:

A new switch can join an established power stack without service interruption - StackPower cables are hot-insertable.

Example

SW-9300-16A#show stack-power budgeting
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 Ring 5720 58 1304 4358 4 8 < ----
Powerstack-15 SP-PS Ring 2860 36 600 2224 2 4 < -----

Power Stack PS-A PS-B Power Alloc Avail Consumd Pwr
SW Name (W) (W) Budgt(W) Power(W) Pwr(W) Sys/PoE(W)
-- -------------------- ----- ----- -------- -------- ------ -----------
1 Powerstack-1 715 715 1408 326 1082 122 /29 < ----- Powerstack-1 (just a name)
2 Powerstack-1 715 715 1438 326 1112 118 /27
3 Powerstack-1 715 715 1408 326 1082 109 /29
4 Powerstack-1 715 715 1408 326 1082 111 /28
5 Powerstack-15 715 715 1412 300 1112 109 /18 < ----- Powerstack-15 (just a name)
6 Powerstack-15 715 715 1412 300 1112 106 /19
-- -------------------- ----- ----- -------- -------- ------ -----------

Enter the following commands on the Switch-Active to turn on the stack-power ports:
#stack-power switch 1 port 1 enable
#stack-power switch 1 port 2 enable
#stack-power switch 2 port 1 enable
#stack-power switch 2 port 2 enable
...

You can also configure a switch connected in a power stack to not participate in the power stack by setting the switch to standalone power mode using the command below. This mode shuts down both Cisco StackPower ports.

9300-STACK#conf t

Enter configuration commands, one per line. End with CNTL/Z.

9300-STACK(config)#

9300-STACK(config)#stack-power switch 1

9300-STACK(config-switch-stackpower)#standalone

On any switch, the switch priority must be lower than port priorities. and the high priority value must be set lower than the low priority value.
it is recommended that you configure different priority values for each switch and for its high priority ports and low priority ports.
This limits the number of devices shut down at one time during a loss of power. If you try to configure the same priority value on different switches in a power stack,
the configuration is allowed, but you receive a warning message.

HTH 

Leonardo 

[jaheshkhan]

thanks. thats a very good explanation in this regard.

In my case all switches are stack-powered together which is wrong. 

So I need to re arrange cables without shutting it down. thats what I preferred. Connections are given below:

SW1 port 1 connected to SW2 port 1

SW1 port 2 connected to SW3 port 1

SW3 port 2 connected to SW5 port 1

SW4 port 1 connected to SW2 port 2

SW4 port 2 connected to SW5 port 2

Planning as below:

SW1, SW2 and SW3 should be stack-powered

Current stackpower setup

SW4 and SW5 should be stack-powered.

In this case do I need to disable stack-power per port or put the switch in standalone powermode without shutting down whole switch?

[Leonardo Pena Davila]

Hi   jaheshkhan,

As I mentioned before, Stack-Power cables are hot-insertable. You should define in a diagram how are you going to connect your  Stack-Power then you can swap the stack-power  cables.  (e.g.. SW 3 port 2 should go to sw 4 port 1 and so on)

HTH

Leonardo