08-23-2023 11:51 AM
Hello, I feel like I am going crazy.
I have a PLC that is on VLAN 10, and production clients and label printers that are on VLAN 100.
Vlan 10 IP range is 172.18.XX.0 range
VLAN 100 is on 10.68.XX.0 range.
C2960 switch
Gi1/0/38 is connected to a smaller "dumb" switch, and the printers, clients, and PLC are connected to that.
If configuring Gi1/0/38 for VLAN 100
switchport access vlan 100
switchport mode access
I can of course ping things on the VLAN 100 network.
Same thing with VLAN 10
switchport access vlan 10
switchport mode access
What I am getting frustrated over is when I configure the interface as a trunk.
switchport trunk allowed vlan 10,100
switchport mode trunk
I am unable to ping any device. I have set the native VLAN (10), I have not put in the "allow" command and left it open as below from the show interfaces trunk command
XXXXXsw-80#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Gi1/0/38 on 802.1q trunking 10
Gi1/0/48 on 802.1q trunking 10
Gi1/0/49 on 802.1q trunking 10
Port Vlans allowed on trunk
Gi1/0/38 1-4094
Gi1/0/48 1,10,100-101,200,412,500,810
Gi1/0/49 1-4094
Port Vlans allowed and active in management domain
Gi1/0/38 1,10,100-101,200,412,500,810,900
Gi1/0/48 1,10,100-101,200,412,500,810
Gi1/0/49 1,10,100-101,200,412,500,810,900
Port Vlans in spanning tree forwarding state and not pruned
Gi1/0/38 100
Gi1/0/48 1,10,100-101,200,412,500,810
Gi1/0/49 1,10,100-101,200,412,500,810,900
I'm not sure what I am missing? I even went back to where the machine used to be connected to and gave it the same configuration that was on its other switch.
08-23-2023 12:29 PM
Are you configuring trunk between the 2960 and the " smaller "dumb"" ?
08-23-2023 01:09 PM
Gi1/0/38 is connected to a smaller "dumb" switch, and the printers, clients, and PLC are connected to tha
i don't think Dumb switch can understand dot1q - so you have limitation using as single VLAN as access port
08-23-2023 01:37 PM
What I am getting frustrated over is when I configure the interface as a trunk.
switchport trunk allowed vlan 10,100
switchport mode trunk
I am unable to ping any device.
From what you've earlier described, that's expected behavior. As @balaji.bandi notes, the dumb switch doesn't understand .1q tagged frames.
I have set the native VLAN (10), I have not put in the "allow" command and left it open as below from the show interfaces trunk command
Okay, after you do that, your dumb switch might allow VLAN 10 to work again, but VLAN 100 still won't work.
What native does, is remove that VLAN's frame tags.
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