> > yes but I guess the question is why? What is the function of the Native
> > Vlan that requires it to be not dot1q encapsulated. Does Cisco just opt
> > for it or is there a logical reasoning behind it... spanning tree seems to
> > ring a bell but am not sure what about spanning tree requries it to be
> > dot1q encapsulation.
>
> Yes. Spanning tree is it. The IEEE spec permits a single unencapsulated
> instance of spanning tree to protect the topology against loops. The
> STP packets are _not_ encapsulated. They run on the the unencapsulated
Well but I think there have been a lot of enhancements after that like
PVST i.e. Per Vlan Spanning Tree. i've seen instances where a vlan trunk
is blocking for one vlan but active for another depending on the topology.
In this scenario BPDU's are local for that vlan broadcast domain
indicating they pare tagged. No other vendor seems to have a concept of
native vlans but Cisco, as soon as you tag/untag a vlan to a port in fdry
or extreme you lose all the default vlan associations to it.
> vlan. There are a few other control packets that must run on the
> unencapsulated lan. Half/full duplex negotiation cannot be encapsulated.
> 802.1x port athentication must also run native. I think flow control
> must also run on the default vlan -- if you believe in L2 flow control.
>
Well auto neg dont' dosen't really communicate via ethernet
frames so its independent of vlans but i think i see what you are
saying, Cisco proprietary DTP could probably make of the Native Vlans.
Nimesh.
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