Michael, Sorry but you are wrong. Trunks are schizophrenic. Access layer ports know the vlan they are in. (switchport access vlan 5). Trunk ports can be in dozens or hundreds of vlans. So the question is....since the trunk can't be in let's say 500 vlans at the same instant in time, what vlan does it default to. What is the native vlan. If you set the native vlan on a trunk to be 90, then when no traffic is being carried, it will think it is in vlan 90. However, if something from vlan 40 hits the trunk interface, spanning tree will enable the trunk to know if it is allowed to carry that traffic. If so, the traffic will cross the trunk and the trunk will 'be' vlan 40 for that instant. This is layer 2 traffic. vlan 40 can only cross vlan 40 trunk. Vlan 95 can only cross vlan 95 trunk. It can't cross vlan 1 or if the native vlan is 3, it can't cross vlan 3. For an instant, trunks can be whatever vlan they need to be provided they are configured for that vlan. Jim
Message: 8 Date: Sat, 5 Mar 2011 00:24:17 -0500 From: Michael Smith <[email protected]> To: <[email protected]> Cc: [email protected], [email protected] Subject: Re: [OSL | CCIE_RS] (ccie_rs)_native_vlan Message-ID: <[email protected]> Content-Type: text/plain; charset="iso-8859-1" Well I know that spanning tree is layer 2 not layer three I was just making a comparison. I'm basically saying that all switch management traffic is sent over the native vlan which is by default 1. And OSPF sends out information to 224.0.0.5. It was probably a terrible comparison but I'm just trying to figure out a way to say basically the native vlan is what the switches send traffic out on. _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
