From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Tue Feb 03 2004 - 16:33:37 GMT-3
> >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.
This is especially true with dot1q tunneling. Leaving the native
VLAN untagged can result in traffic that was meant to be tunneled leaking
into the transit network. You can use the global command "vlan dot1q tag
native" to ensure that the native VLAN gets a tag.
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
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