From: Peter van Oene (pvanoene@juniper.net)
Date: Tue Feb 03 2004 - 09:45:32 GMT-3
At 01:04 PM 2/2/2004, Bob Sinclair wrote:
>Danny,
>
>802.1Q is an IEEE standard. It can be downloaded free from the following
>link:
>
>http://standards.ieee.org/getieee802/802.1.html
>
>It is critical when using 802.1Q trunks that you are consistent with the
>native vlan. When you trunk non-Cisco switches running 802.1Q to Cisco
>Switches running PVST+, there is a common spanning tree running on the
>native vlan. Native vlan inconsistencies can result in bridging separate
>spanning trees together. Here is a link that offers more detail on this
>scenario:
As long as you tag all vlans, I don't think this is an issue. Leaving one
untagged is the risk.
>http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121t/121t3/dtbridge.htm
>
>HTH,
>
>Bob Sinclair
>CCIE #10427, CISSP, MCSE
>www.netmasterclass.net
>
>
>----- Original Message -----
>From: <Danny.Andaluz@triaton-na.com>
>To: <ccielab@groupstudy.com>
>Sent: Monday, February 02, 2004 12:37 PM
>Subject: 802.1q native vlan/router-on-a-stick
>
>
> > Hello, Group.
> >
> > What exactly is the native vlan used for?
> >
> > I've done practice scenarios where the native vlan is required to be
> > specified and others where this is not needed. Both ways work. So what
> > exactly is the purpose of the native vlan in 802.1q?
> >
> > For example, one setup would be where a router is routing for vlans 45 and
> > 34 and vlan 45 is configured as the native vlan on the router
>sub-interface
> > and the switchport. What is the difference between vlan 45 and vlan 34 in
> > this case? What traffic, if any, is sent on vlan 45 that is not sent on
> > vlan 34?
> >
> > Using the same scenario, I specify no native vlan on either interface and
> > traffic is still routed by the router for both VLANs.
> >
> > I tried to find an RFC for 802.1q and no luck. The Doc CD doesn't really
> > clear this up either.
> >
> > Thanks,
> > Danny
> >
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