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Community Member

4006 layer 3 and native Vlan

With reference to Alonza-Garza's conversations (4006 RSM question WS-X4232-L3), I'm also trying to set up a Cat4006 (in a test area) with a layer 3 supy card (separate card) and I'm confused why there needs to be a 'native' Vlan for management purposes only. I understand from the documentation about certain types of traffic needs to be processed in software (as apposed to hardware), but is this native Vlan purley for management traffic between the layer 2 and 3 cards and therefore would NOT be extended out to the user ports? Sorry, if this is a basic question, but this is the first time I have come across this term. Appreciate some explantion if anyone can help. Thanks in anticipation.

regards, Mark

2 REPLIES
Community Member

Re: 4006 layer 3 and native Vlan

The DOT1Q specification forces you to choose a native VLAN and it shouldn't be used for production, only management. I believe all trunks transport multiVLAN traffic over the native VLAN therefore the virtual trunks to the layer 2 switch use the native VLAN. That's my story and I'm sticking with it..

Community Member

Re: 4006 layer 3 and native Vlan

Just ran into same scenerio. I'll start with a quote from a Layer 3 install guide. "You must configure a subinterface as a native VLAN for each physical interface, otherwise the main interface (g3 or g4) will be assigned a native VLAN of 1. If the native VLANs do not match on both sides of the connection, packets will be lost." When configuring for multiple VLANs across the same interfaces, the "native" VLAN here signifies which VLAN is the Management VLAN- a requirement for any switch. And we know VLAN 1 is always the default Management VLAN. Basically yes, it's for management info passed between the L2 and L3 backplanes.

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