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New Member

Adding an additional switch and making it a stack.

I currently have Cisco 3750G which is currently live and active and fully populated and only have remote access.

I have an additional same switch which I would like to stack. My initial plans were to have 2 GIbit etherchannels, but I came across the option to Stacks both switch with each other.

When I do a show switch on the live switch its set as a Member:

Switch/Stack Mac Address : 081f.f30f.1c80

                                          H/W   Current

Switch#  Role   Mac Address     Priority Version  State

----------------------------------------------------------

*1       Master 081f.f30f.1c80     1      0       Ready

When I do a show switch on my new switch this is the output shown:

Switch/Stack Mac Address : d824.bd89.9800

                                           H/W   Current

Switch#  Role   Mac Address     Priority Version  State

----------------------------------------------------------

1       Member 0000.0000.0000     0      0       Provisioned

*2       Master d824.bd89.9800     1      0       Ready

I would like to add the new switch to the stack without losing the config for the switch which is live.

I understand that the highest priority of the switches becomes the Master but as the live switch is Priority 1, would chancing this affect the switches config, or would it lose connection at all?

Also when I plug in the new switch and it reboot how do I ensure it becomes the slave without rebooting the live switch?

The cables on the switch do they have to go to port1 on the live switch and port 1 on the new switch or can they be port 1 and port 2?

Thank you.

19 REPLIES

Re: Adding an additional switch and making it a stack.

Hi

the trick here is:

- give the master switch priority 15.

- give the new switch prio 1 (or lower than 15)

- connect the new switch with stack cables.

- power the new switch up.

This way you will still have your config

Now that you already connected it, it can get tricky.

I d try to configure the prioirities now thats in stack: 15 for the master and like 13 for the new switch

Then save your config

Reload the stack

Check your config

As for the cables, i assume you mean stack cables.

Stack cable from switch 1 goes from stackport 1,  to switch 2, stackport 2

Stack cable from switch 2 goes from port 1,  to switch 1, port 2

Good luck

New Member

Re: Adding an additional switch and making it a stack.

Hi,

Once I have the new switch installed with the priority 1, is there any reason I would change it to 13. I am only ever going to have a total of two switched stacked.

Also if change the priority on the live switch which is currently one, would this cause any affects to the devices/host connected or would the switch have to reboot?

I only have one stackwise cable, would I still connect it the same way? As I only have one cable would it be better to use etherchannel, as then I would have failover?

Thank you.

New Member

Re: Adding an additional switch and making it a stack.

Also to add, I don't understand what they mean by a provisioned switch?

New Member

Re: Adding an additional switch and making it a stack.

Hi,

Have you checked that if both siwtches have the same IOS ?

New Member

Adding an additional switch and making it a stack.

Hi,

"I only have one stackwise cable,  would I still connect it the same way? As I only have one cable would it  be better to use etherchannel, as then I would have failover?"

You have to use 2 stack cable's.

New Member

Adding an additional switch and making it a stack.

Yes both switches are running the same IOS.

I only have one stackwise cable therefore I guess I would not be able to use this, and would use etherchannel.

Could someone please help with the following questions:

Once I have the new switch installed with the priority 1, is there any reason I would change it to 13. I am only ever going to have a total of two switched stacked?

Also if change the priority on the live switch which is currently one, would this cause any affects to the devices/host connected or would the switch have to reboot?

Cisco Employee

Re: Adding an additional switch and making it a stack.

There is no reason for you to change the priority to the pther switch to 13, you can keep 1 if you like. Also changing the priority of the stack master switch wont affect anything your service, dont worry at all

Sent from Cisco Technical Support iPhone App

New Member

Adding an additional switch and making it a stack.

Thanks Diego,

I will increase the live switch which I want to be the master to 15.

I have read the document about the provisied switch, I have configure the second switch just with SSH access and a IP address, how do I ensure that the the live switch config is not lost when the member is joined to the master?

Adding an additional switch and making it a stack.

John

Two stack cables are not needed but recommended:

- stack cable redundancy

- 32 Gbps backplane in case of two stack cables; 16 Gbps backbone with one stack cable

the procedure to add a second switch

while the active switch is powered on:

1) mount the second switch (no configuration is needed on the second switch)

2) connect the stack cable

3) power on the second switch

4)monitor via the console port of the active switch

*when the second switch is booted*

#show switch  ! this will show all the switches in the stack+ configured priority

#show interface status !you'll see the new ports of the second switch (2/0/x)

All the ports of the second switch are unconfigured.

With provisioning is meant --> configure an extra switch on the existing stack, while it's not connected yet via

switch

The second switch don't have to preconfigured

I think you should start with the first method and outside business hours. Normally this task is done without outage but for your first time, take no unnesarry risks

Don't bother about the switch priorities. Make sure the IOS version is the same

New Member

Adding an additional switch and making it a stack.

Thanks,

IOS version are the same.

I have only configure the basics on the new switch hostname and ip address and its on its way to the site.

If I don't set the switch priorites when there is a power outage I don't want the new switch to become the master.

Adding an additional switch and making it a stack.

No configuration is required on the new switch. The new switch will download the configuration from the other switch.

You'll end up with 2 physical switches which form together 1 logical switch

1 logical switch means - 1 mgmt IP, 1 ...

it's not wrong to configure switch 1 priority 15

If possible/available:

-connect power cable switch 1 to power circuit 1 ; power cable switch 2 to power circuit 2

-check also for cross-stack etherchannel for uplink redundancy in case 1 switch reboots

HTH

please rate helpfull posts

New Member

Adding an additional switch and making it a stack.

Hi Davy,

Thanks for all your help.

The problem is that I have already configure the switch and one of my team member is going to install the switch and there is no way I can wipe the config.

Is it ok to follow your steps when the switch is pre-configured, one the switch joins the stage I don't care it is wiped?

Adding an additional switch and making it a stack.

best practice/recommended is to start with a /wr erase

When you add a switch to a stack, the stack master automatically changes the configuration of the new switch. The master switch revises the new member switch port numbers to conform to the current port numbering sequence in the stack. Any existing port-level configuration in the newly-added switch is automatically cleared or updated.

As I said before - always good to perform in a maintenance window-

HTH

please rate helpfull posts and let us know how it went

New Member

Adding an additional switch and making it a stack.

Hi,

I have a live switch which has the following IOS:

Cisco IOS Software, C3750 Software (C3750-IPSERVICES-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1)

ROM: Bootstrap program is C3750 boot loader

BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(25r)SEE4, RELEASE SOFTWARE (fc1)

System image file is "flash:c3750-ipservices-mz.122-35.SE5/c3750-ipservices-mz.122-35.SE5.bin"

cisco WS-C3750G-24TS-1U (PowerPC405) processor (revision F0) with 118784K/12280K bytes of memory.

The switch which I want to add as a member is:

Cisco IOS Software, C3750 Software (C3750-IPSERVICES-M), Version 12.2(50)SE5, RELEASE SOFTWARE (fc1)

ROM: Bootstrap program is C3750 boot loader

BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(44r)SE8, RELEASE SOFTWARE (fc1)

System image file is "flash:c3750-ipservices-mz.122-50.SE5/c3750-ipservices-mz.122-50.SE5.bin"

cisco WS-C3750G-24TS-1U (PowerPC405) processor (revision J0) with 131072K bytes of memory.

Would these be able to join the stack or would the new switch need a downgrade?

Thanks

Adding an additional switch and making it a stack.

Switches with different major Cisco IOS software versions usually have different stack protocol versions. Switches with different major version numbers are incompatible and cannot exist in the same switch stack.

A downgrade of the new switch is needed

HTH

please rate helpfull posts

New Member

Adding an additional switch and making it a stack.

Thanks,

I am about to install the switch, the live switch has a default command which says something along the lines of switch 1 provision ws-3560g-ts etc...

The problem is that before I sent the switch to be installed by the enginner, I changed the switch number to 2, there the switch to be stacked is showing itself as number 2, would this affect the switch 1 provision ws-2560g-ts command to the live switch?

Hall of Fame Super Gold

Adding an additional switch and making it a stack.

I am about to install the switch, the live switch has a default command which says something along the lines of switch 1 provision ws-3560g-ts etc...

I hope this is a type-o.  A 2560G/3560G?

New Member

Adding an additional switch and making it a stack.

The switch is a 3560 which has Gigibit ports.

Do I need to change the switch 1 provision... to switch 2 provision on the live switch, as I've changed switch to be stacked to switch 2?

Hall of Fame Super Gold

Adding an additional switch and making it a stack.

3560 do NOT support stacking.

3560 will support an ancient form of "stacking" called switch clustering.

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