(Another) VLAN question...

Unanswered Question
Apr 5th, 2009
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Say you have this config (found on internet browsing)...

interface FastEthernet0/19

description AP1120G-Gnd

switchport access vlan 50

switchport trunk encapsulation dot1q

switchport trunk native vlan 50

switchport trunk allowed vlan 50,51

switchport mode trunk

switchport nonegotiate


How can this work, having an access port and trunk on same port? A trunk port will allow all VLAN, but this is pruned to only let VLANs 50 and 51 through, but then why the sw ac vl 50 cmd?

Again, this is just someones config I found on internet, so it might be incorrect.

Thx again

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Overall Rating: 5 (1 ratings)
lamav Sun, 04/05/2009 - 11:07
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I can fully understand why you are confused. One normally configures a port to be an access port or a trunk port. This is configured as both.

The reason that this is done is to have a deterministic failure scenario in the event that the port stops trunking. If the port ceases to trunk properly, it will automatically place itself in vlan 1. This configuration is meant to force into vlan 50 instead.




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