From: NET HE (he_net@hotmail.com)
Date: Tue Feb 03 2009 - 23:23:20 ARST
I used ethereal to decode the layer 2 traffic in a trunk.
1)for a trunk with default vlan 1 as native
DTP/PAGP/VTP/CDP has no vlan tag with LSAP 0XAAAA, CST (IEEE STP) has no vlan
tag with LSAP 0x4242, pvst+ vlan 1 has vlan 1 tag with lsap 0xaaaa, etc.
2)for a trunk with vlan 100 as native
DTP/PAGP/VTP/CDP has no vlan tag with LSAP 0XAAAA, CST (IEEE STP) has no vlan
tag with LSAP 0x4242, pvst+ vlan 100 has vlan 100 tag with lsap 0xaaaa, etc.
So basically, to my understanding, not allowing native vlan is just to stop
native vlan's pvst+ and traffic. It doesn't affect CST, DTP, PAGP, VTP, CDP.
Best Regards, Net (Xin) He > Date: Wed, 4 Feb 2009 11:16:07 +1100> Subject:
Re: Trunking question 'switchport trunk allowed vlan'> From:
dale.shaw@gmail.com> To: all.from.nj@gmail.com> CC: mcnever@gmail.com;
sadiqtanko@gmail.com; ronnie.angello@gmail.com; ccielab@groupstudy.com> > If
you've got the inclination, I'd like to know what a protocol> analyser says
about CDP (etc.) frames when you:> > a) change the native VLAN from 1 to
something other than 1 (do they> egress the port with a tag of 1, or no tag
and therefore in the> non-VLAN1 native VLAN?)> b) tag the native VLAN (do they
egress the port untagged, or if> they're tagged, are they tagged 1 or with the
non-VLAN1 native VLAN?)> > cheers,> Dale> > On Wed, Feb 4, 2009 at 10:18 AM,
ALL From_NJ <all.from.nj@gmail.com> wrote:> > Hello Team,> >> [...]> > Any
suggestions for additional 'learning-tests'? Thanks Jason and others> > for
the questions and discussions ...> > > Blogs and organic groups at
http://www.ccie.net> >
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