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New Member

3560 connected to 2960S stack native and voice vlan issues

We have a 2960S stack which has a 3560 (leaf node, not routing) plugged into it.  When the 3560 gets unplugged from the 2960S stack, anything on the voice vlan on the 2960S stack starts to act funky, such as calls are only heard on one side or phones can’t get DHCP.  Also when that 3560 switch is unplugged, anything on the 2960S stack which has the command “switch port trunk native vlan 193”, which are our APs, causes anything on vlan 193 to act up as well.  We have found that if we connect the 3560 and plug anything into an access port on vlan 193 on the 3560, it causes everything on the 2960S stack to work fine.  The strangest thing is that when we remove the 3560 from the environment, it breaks what is still in place, the 2960S stack, even though no traffic is routed through the 3560 and the 3560 does nothing of any significance besides provide layer 2 access.

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New Member

I forgot to mention versions

I forgot to mention versions of code on these switches.

2960S stack - 12.2(55)SE7

3560 - 12.2(35)SE5

Hall of Fame Super Gold

3560 - 12.2(35)SE5

3560 - 12.2(35)SE5

I'd be upgrading the IOS for the 3560 to something more recent before doing any more troubleshooting.  


For 3560, I'd recommend 12.2(55)SE9.

What is the status of the

What is the status of the spanning tree on these switches for the affected VLANs? Is there something in STP causing funnies, every time you unplug the switch? Also perhaps config outputs can give us an understanding of the setup, in order for us to assist more.

Please rate useful posts & remember to mark any solved questions as answered. Thank you.
New Member

Nothing is showing up in the

Nothing is showing up in the logs regarding STP when the issue occurs.  Let me work on getting configs.

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