How do you change who is the master switch in a 3750 stack

[didentx01]

We have 2 3750 24 port fiber switches in a stack and we would like to change the member to become the master. Both are running the same IOS and they are alive on the network. I read that you can change the who becomes the master by setting the priority number higher on the member, which we did. However this requires a reboot of the member to take effect. Is there a way to force this without having to reboot? One other note, both switches in stack have a single gig connection that goes to the core (6500). One gig link is blocked due to spanning-tree and this is on the member that we want to become the master. Will this cause an issue.          

[allan.thomas]

Hi,

Unfortunately as you already know reloading the switch member is the only way for the switch priority to take effect and force a re-election of the master. If you have redundant paths to your core it doesn't make a difference which uplink is blocking, traffic will transit the backplane from one member to the other and forward accordingly. If you have only one core 6500 which both uplinks from the stack connect back to you might want to consider using port channel to utilise both uplinks?

Regards
Allan

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[didentx01]

Thanks! Unfortunately, we do not have access to the core at all but the access switches my group does. The group that put in these switches thought it would better to have a gig link from each switch in the stack go back to the core and let one of the link be blocked like spanning-tree suppose to. So if I have already set the priority on the member switch to 10, reboot the master, the member will become the master and the master the member, when it comes back up. Since spanning-tree is blocking the interface on the member switch, once the master is re-booted, the member gig interface to the core will start forwarding after about a minute.

[allan.thomas]

Hi,

The uplink from the master may still not necessarily be the forwarding uplink as you will have two equal cost paths to the designated root bridge the single 6500 in the case, thus you may find it necessary to increase the port cost on either the uplinks to obtain the desired results.

Regards
Allan

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