Questions about switch stacking

[Alexander Simbun]

Hello all,

I have a few questions regarding switch stacking;

1. Is it possible to stack two different switch models (WS-C3850-48T & WS-C3850-48U) using data stack cable and power stack cable?
2. Do I need to manually upgrade the firmware on each standby switch before forming a stack with the master switch?
3. During the forming of switch stacking, I need to reboot those switches for the changes to take effect. Do I need to reboot all the switches or only those standby switches?

Thank you very much in advance.

Alex.

[Leo Laohoo · Accepted solution]

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@Alexander Simbun wrote:

Is it possible to stack two different switch models (WS-C3850-48T & WS-C3850-48U) using data stack cable and power stack cable?

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Yes.  Both units must be running the same IOS-XE version. 

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@Alexander Simbun wrote:

Do I need to manually upgrade the firmware on each standby switch before forming a stack with the master switch?

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Yes.  

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@Alexander Simbun wrote:

During the forming of switch stacking, I need to reboot those switches for the changes to take effect. Do I need to reboot all the switches or only those standby switches?

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No.  DO NOT connect the stacking cables if the switch members still have power.  Make sure the switch members have NO POWER before connecting the stacking cable.  

[balaji.bandi · Accepted solution]

1 - yes that works

2 - same IOS upgrade is good to stacking

3. you need select Master or slave based on the switch number and priority, make sure device off before connecting stack cables is the suggested method.

Look at the stacking document :

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/hardware/installation/guide/b_c3850_hig/b_c3850_hig_chapter_010.html

[Joseph W. Doherty · Accepted solution]

#1 In general, for Cisco stackable switches, you can mix and match all models in the same series, and sometimes the same "family".  However there are exceptions.  You should review the corresponding documentation for the switches in question.  (BTW, as the other posters have already noted, I believe the answer is also yes for those two particular switches.)

#2 Depends whether it differs from what the existing stack is using.  Also, some stackable switches allow "minor" differences between stack members.  (NB: the "safe bet" is to use the same IOS image and license on all member switches.)  Also BTW, some devices have other firmware revisions, separate from the main IOS, which may require, in some situations, manual updating.  (NB:  switches requiring a firmware update, for a particular IOS, that IOS will often "auto update" the firmware when you update to that IOS.)

#3 Often no reboot is necessary.  Generally the only "requirement" is the to-be-added switch is powered off when making  stack connections.  Once connected, just power it on.  Depending on the switch series, you can sometimes even "pre-configure" its ports before adding it to the stack.  (I.e. when powered on, it immediately is a functional member of the stack.)