[c-nsp] native vlan & tagged ?

[Jack Parks]

Comments inline...


On Fri, 4 Mar 2005 14:07:46 -0800, matthew zeier <mrz at intelenet.net> wrote:

> My goal is to have the IPMI on Vlan10 and have the server on Vlan10 and
> "something else" (whatever network the customer is on).   The IPMI BMC card
> doesn't understand trunking of dot1q.
> 

More specifically, it is the native vlan (untagged) that the IPMI
doesn't understand?

> Under Linux, this is no problem - eth0 can handle untagged frames and
> eth0.<vlan> can handle tagged frames.
> 
> Under Windows, the Intel driver doesn't appear to let me create an untagged
> interface (or if it doesn't I don't know how to do it).  My switch config
> looks like:
>

The "native vlan" is a throw back from the early ISL/.1q days.  It was
used to pass BPDU/CDP/etc. (if I remember correctly).  As suggested
earlier in the thread, tag all VLANs with "vlan dot1q tag native" or
remove "switchport trunk native vlan 10" from your config.

> interface GigabitEthernet0/17
>  switchport trunk encapsulation dot1q
>  switchport trunk native vlan 10
>  switchport trunk allowed vlan 10,170
>  switchport mode trunk
>  speed auto 10 100
>  no cdp enable
>  spanning-tree portfast trunk
> end
> 
> Is the any way to have vlan10 native but also tagged?  Or is there some
> other way to do this?

There is no reason to use/set the native vlan.  Typically, VLAN 1 is
the native vlan.  If you are using VLAN 1 and need to pass VLAN 1
traffic over a .1q trunk, then:
(a) use the "vlan dot1q tag native" command (*recommended)
(b) change the "native VLAN" to another VLAN id (one that you are not
using on the trunk)

In your case, since both Windows and Linux understand tagged frames,
the removal of "switchport trunk native vlan 10" from your interface
config should do the trick.