Untagged VLAN on Trunk Port - help please

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Mar 30th, 2010
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Hi folks.

I need to configure a port on a 3750E to support the following:

The port will connect to an Outreach Quad switch, and on the switch I will have 1 x 1130 LAP and on IP device. The Outereach switch is apparantly invisible to VLANS, and will forward both tagged and untagged traffic.

I need the port on the 3759 to accept traffic from the AP and allocate it to one VLAN and allocat the other IP device to another VLAN.

I am looking at sub interfaces (  the 3750 does not support them, i don't thnk) or SVI, or some other methid.

Please would anyone help and advise.

Many thanks,


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Giuseppe Larosa Tue, 03/30/2010 - 06:14
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Hello Neil,

unless the IP device can be configured to use a vlan tag (for example this happens wit VMware instances) both devices will be in the native vlan.

you cannot use subinterfaces on the C3750 so probably your only way to accomodate IP addresses in two different IP subnets is to use ip address secondary under an SVI interface

interface vlan 1

ip address

ip address secondary

this can do the trick

Hope to help


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