switch stack

[suthomas1]

Hello All,

Please help me on how to stack together 3 3750 or 3650 switches. What are the configuration steps involved.

Does the configuration done on master sync by itself to the slaves once the stack is created.

Thanks in advance

[manju.cisco]

Hi,

Yes, the switch automatically sync itself with other switches on stack.

Have these checks before hand.

Make sure all your switches should have same IOS versions in it to boot. You can check this by booting it up as standalone switch and checking the version of it. If incase the versions are different on each switch then you will not be able to stack properly, you will see msg as version mismatch.

Keep a local copy of an IOS and push it to the switches from your laptop or tftp individually.

Power OFF your switches.

Then make sure you interconnect your switches with stack cables properly.

Then power on the switch which you want to make as master switch.

And then power on the rest of switches one by one.

Regards,

Manjunath

[suthomas1]

Thanks Manju for the reply.

So, if i power on Switch 1 , configure it with vlans etc, i do not need to explicity do the same on Switch2&3?

Also , stacking is determined by which switch comes first. Which means there is no specific command to enable stacking or choosing master role.?

In that case, what happens if master switch fails.

[ranraju]

Hi,

There is no specific command to enable stacking. But you can choose a master switch by assigning it a priority. Command for that would be "switch stack-member-number priority new-priority-value" - highest priority value that you can assign is 15, and stack member with priority 15 would likely become the master when the switches reload.

If the master switch fails, all the switches will reload and there would be an election again, switch with highest priority would come up as the master.

Each switch will have a copy of the configurations of the whole switch. So if you create a vlan, that information is with all the switches in the stack. Also, when you setup a stack of switches, it would be considered as a single switch and it also behaves like one. You cannot configure each switch in the stack by logging into it individually, but you can run some limited show commands on them when they are in the stack. All the configurations are done on the master.

Hope this helps, and answers your queries.

Regards,

Ranganath

(TAC)

[manju.cisco · Accepted solution]

Yes, when you power on Switch 1 and then configure it.....then there is no necessary to configure Switch  2 & 3.

Switch 1's config will be called as master config and the same will be pushed to Switch 2 & 3 also.

So whatever the configs you have in Switch 1 will also be present in Switch 2 & 3 automatically.

Yes, stacking is determined by which switch ONLY IF all the swithces have same stack priority. If any switch which has higher priority than other switches will become master even after if it is powered up at last.

Command to change switch priority will be switch stack-member-number priority priority-value

Incase of master switch failure, anyone of the slave switches(if priority is same among them) will become master or else new election happens and higher priority switch will be elected as master and it will have the same configs as the previous master configs. So you will still be able to manage the stack switches.

However, the ports connected to previous master switch shall remain down

So if you have critical servers connected to this stack switch, either use one cable to each stack switch from the server and configure it as ether channel, so that if one stack switch fails, you will still have connectivity thorough other stack switch.

Thanks,

Pls rate helpful posts.

[suthomas1]

thanks again. If in this case my 3 stacked switches are to be connected to the Core-comprising of 2 6509's, how would that be best done.

thanks.