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Add a "Fifth" Cisco switch into current "Four Stack-wise" Cisco Configuration

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Last Modified: 2018-04-27
I need to add a new Cisco switch to a current stack of 4 Cisco switches smoothly. I need to know the process. This is what i have:
1) New switch (turn on make sure it matches same ios version, same licenses and set priority to 1)
2) turn off switch
3) Connect new switch to the stack and properly wire cables. (as in the figure below)
4) Turn on new switch
5) wait 10 mins
6) do show switch (to ensure new switch is there). Below is my config.

sw-1#show switch
Switch/Stack Mac Address : 38ed.18ac.xxxx - Local Mac Address
Mac persistency wait time: Indefinite
                                             H/W   Current
Switch#   Role    Mac Address     Priority Version  State
------------------------------------------------------------
*1       Active   38ed.18ac.xxxx     15     V05     Ready
 2       Standby  38ed.18c0.xxxx     1      V05     Ready
 3       Member   5006.04c6.xxxx     1      V04     Ready
 4       Member   38ed.18da.xxxx     1      V05     Ready
sw1#show license right-to-use usage
 Slot#  License Name     Type     usage-duration(y:m:d)  In-Use  EULA
-----------------------------------------------------------------------
 1      ipservices     permanent    2 :6 :24               yes   yes
 1      ipservices eval evaluation   0 :0 :0                no    no
 1      ipbase         permanent    0 :0 :0                no    no
 1      ipbase eval    evaluation   0 :0 :0                no    no
 1      lanbase        permanent    0 :0 :0                no    no
 1      apcount eval   evaluation   0 :0 :0                no    no
 1      apcount        base         0 :0 :0                no    no
 1      apcount        adder        2 :6 :24               yes   yes

 Slot#  License Name     Type     usage-duration(y:m:d)  In-Use  EULA
-----------------------------------------------------------------------
 2      ipservices     permanent    2 :6 :24               yes   yes
 2      ipservices eval evaluation   0 :0 :0                no    no
 2      ipbase         permanent    0 :0 :0                no    no
 2      ipbase eval    evaluation   0 :0 :0                no    no
 2      lanbase        permanent    0 :0 :0                no    no
 2      apcount eval   evaluation   0 :0 :0                no    no
 2      apcount        base         0 :0 :0                no    no
 2      apcount        adder        2 :6 :24               yes   yes

 Slot#  License Name     Type     usage-duration(y:m:d)  In-Use  EULA
-----------------------------------------------------------------------
 3      ipservices     permanent    2 :6 :13               yes   yes
 3      ipservices eval evaluation   0 :0 :0                no    no
 3      ipbase         permanent    0 :0 :0                no    no
 3      ipbase eval    evaluation   0 :0 :0                no    no
 3      lanbase        permanent    0 :0 :0                no    no
 3      apcount eval   evaluation   0 :0 :0                no    no
 3      apcount        base         0 :0 :0                no    no
 3      apcount        adder        0 :0 :0                no    no

 Slot#  License Name     Type     usage-duration(y:m:d)  In-Use  EULA
-----------------------------------------------------------------------
 4      ipservices     permanent    2 :6 :24               yes   yes
 4      ipservices eval evaluation   0 :0 :0                no    no
 4      ipbase         permanent    0 :0 :0                no    no
 4      ipbase eval    evaluation   0 :0 :0                no    no
 4      lanbase        permanent    0 :0 :0                no    no
 4      apcount eval   evaluation   0 :0 :0                no    no
 4      apcount        base         0 :0 :0                no    no
 4      apcount        adder        2 :6 :24               yes   yes
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Sr. Network Engineer
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Commented:
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Author

Commented:
LVL12, my current config is as below. Also i changed my power connection. Please advise if this is the final draw.
sw-1#show switch
Switch/Stack Mac Address : 38ed.18ac.xxxx - Local Mac Address
Mac persistency wait time: Indefinite
                                             H/W   Current
Switch#   Role    Mac Address     Priority Version  State
------------------------------------------------------------
*1       Active   38ed.18ac.xxxx     15     V05     Ready
 2       Standby  38ed.18c0.xxxx     1      V05     Ready
 3       Member   5006.04c6.xxxx     1      V04     Ready
 4       Member   38ed.18da.xxxx     1      V05     Ready
Stack-Wise-cisco-new.jpg

Author

Commented:
I was planing to put the new switch with priority of 1 as i see that the Standby by has 1, and all other two members has 1. i want to keep it like that. what is the down side?
atlas_shudderedSr. Network Engineer
CERTIFIED EXPERT

Commented:
Sorry so long getting back to you Faustino.  Regarding the new JPG, yes, your planned configuration is correct.

Regarding priority.  Generally, priority is used to control which switch next takes the master roll in the event of a primary master failure.  To the best that I have been able to determine over the years there is not specified need to number the stack members from a raw operational perspective.  That said, I can tell you that there is general agreement that controlling master election through renumbering is community recommended for a couple of reasons.  First, you generally want the master to contain only access links and no uplinks.  In the event that the master fails, the idea is that a new master will be elected and access will be lost for those attached end users of the failed unit but with no impact to the overall stack.  Anecdotal I know but it does make some degree of sense.  Second, by controlling election and priority of the switches in the stack, should you have a failure, the task of identifying the problematic device is eased.  Without numbering, you will need to determine the device MAC of each switch via CLI and compare that against the MAC labels of each device to determine which is which.  If you number and therefore control the priority of the switches in the stack, you can then add external labeling to match, kick-starting the troubleshooting process.  Again, anecdotal I know but it is actually helpful from experience.  Not all failures result in a power down scenario and having to first eliminate the good from the bad before actual troubleshooting can cost in terms of MTR and stress.

Hope that helps.

Author

Commented:
LVL12. Thanks a lot. Good. Fair. can i change the priority number to look like below, without affecting production. Does a reboot is required after that? can i  do it before adding the new SWITCH?  let me know. Thanks.  Please provide commands example.

SWITCH       PRIORITY
SWITCH-1      15
SWITCH-2      14
SWITCH-3     13
SWITCH-4     12
SWITCH-5      11
atlas_shudderedSr. Network Engineer
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Commented:
Changing priority doesn't require a reboot.

SWITCH#show sw
Switch/Stack Mac Address : cc5a.5338.2580
                                           H/W   Current
Switch#  Role   Mac Address     Priority Version  State 
----------------------------------------------------------
*1       Master cc5a.5338.2580     15     4       Ready               
 2       Member cc5a.5338.4e80     11     4       Ready               
 3       Member cc5a.5338.3080     13     4       Ready
!
!
!
SWITCH#conf t
!
!
!
SWITCH(config)#sw 2 priority 11
Changing the Switch Priority of Switch Number 2 to 11
Do you want to continue?[confirm]
New Priority has been set successfully
!
!
!
SWITCH(config)#end
SWITCH#wr mem
SWITCH#exit

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