I can't answer your question about the default DSCP value without lab-ing it, but as to the second part: yes, it's generally a good practice to either pick a bogus/dummy VLAN for your native, or to apply the command "vlan dot1q tag native" to force it to apply a tag even on the native VLAN.
If you need the native VLAN untagged, like to present a potential trunk port as an access port for untagged hosts, then "trust cos" might be inappropriate. Like you I would expect the DSCP to default to zero, but maybe someone else has the answer... -Geoff On Tue, May 19, 2009 at 11:20 AM, Matthew Huff <[email protected]> wrote: > I have a question about QOS trust between two 6509 switches connected via a > L2 802.1Q trunk with multiple VLANs. If the port is set to "trust cos", what > does the internal DSCP value get set for native frames since their isn't a > COS field? I would assume the internal DSCP value would be set to the default > or normally zero. Do most people then set the native VLAN to a unused VLAN so > that native packets have internal DSCP values set? Or do most use "trust > dscp"? If so, what do people use "trust cos" for? > > > > ---- > Matthew Huff | One Manhattanville Rd > OTA Management LLC | Purchase, NY 10577 > http://www.ox.com | Phone: 914-460-4039 > aim: matthewbhuff | Fax: 914-460-4139 > > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
