3750G Stack Master reboot affects the traffic?

Unanswered Question
Aug 29th, 2010

Hi All,

We have two 3750G stacked switches. The server has two interfaces connected to each switch. When the master switch reboots, during the re-election approximately 40 seconds, I lost the ping to the server. When I rebooted the member switch, no ping was lost. Is there any way to configure 3750G not affect the traffic when the re-election happens? If no, I think unstacking them may solve the problem.

Thanks a lot for the help!


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Leo Laohoo Sun, 08/29/2010 - 15:21

Is there any way to configure 3750G not affect the traffic when the re-election happens?

Use the command "switch 1 priority 15".  This will tell the stack that switch 1 will always be the master and minimizing the boot time because master election has been statically configured.

Hope this helps and please don't forget to rate our useful posts.  Thanks.

hxmengmetro Sun, 08/29/2010 - 20:56

Thanks for quick reply. I set "switch 1 priority 2" and "switch 2 priority 1". But when I reboot switch 1, switch 2 take over as a master. When switch 1 came back, switch 2 is still master. It didn't act like what I thought. Is there anything I'm missing?



Nagaraja Thanthry Sun, 08/29/2010 - 21:19


When you have a master active in the stack, if the previous master comes

back up, it will not takeover the master role. It will become master (in

your setup) only when the current master goes down.



Leo Laohoo Sun, 08/29/2010 - 21:23

I set "switch 1 priority 2" and "switch 2 priority 1".

Awwww, that's nothing.  Default is "1" which means enable master stack election.  "15" means no election and switch is the master.
Nagaraja Thanthry Sun, 08/29/2010 - 16:22


Set priority for all switches in the order in which you would like them to

assume master role. In that way, when the master goes down, the other device

takes over right away. There will be a slight delay in learning routing

information but that should not affect layer 2 packet forwarding.

Hope this helps.



hxmengmetro Sun, 08/29/2010 - 20:58

Thanks for your thought. I'm observing the uplink to our main switch came down and up. During that time, uplink traffic is down for 30 seconds like. I haven't verified the layer 2 traffic. Our goal is just to make sure the layer 2 traffic is not affected. I will test it tomorrow. Thanks.



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