Thats right I am how in the light. Great discussion ! I remember in the old days before cdp version 3 the phones had to have vlan trunk configured with native vlan for the pc vlan. But that is another story, but then it was clearer in what mode the phone was connecting. But it was terrible that you had to be carefull til filter out unneccesary vlans on all phone ports.
But thank you guys very much. Now I sense that there is danger to leave the phone in access vlan only if you don´t realize what will happen to tagging. regards. Kristjan -----Original Message----- From: Ralph Olsen [mailto:[email protected]] Sent: 16. ágúst 2011 18:11 To: Kristján Ólafur Eðvarðsson Cc: [email protected] Subject: Re: [OSL | CCIE_Wireless] Very basic wired phone QOS question Hi Kristján, The access vlan x and voice vlan y would be similar to do switchport trunk enca dot1q switchport trunk allow vlan x,y switchport trunk native vlan x So, the show inter trunk would not show the voice vlan "trunk" interface, but it sure is there. So you would trust cos on both the voice vlan config and the complete trunk port config. alternatively you could trust device cisco-phone if available. If the voice vlan config was not there no frames would be have the dot1q add-on and hence no COS field to trust. You would trust trust DSCP in that case. /Ralph 2011/8/16 Kristján Ólafur Eðvarðsson <[email protected]>: > I can´t believe that I am asking this but what the the heck :D > > A cisco phone connected to a switch. > > ! > switchport mode access > switchport voice vlan x > switchport access vlan x > ! > I have somehow considered the phone to send COS layer > 2 packets on the voice vlan because the phone is actually > trunking (after negotiating voice vlan with cdp) data and user vlan. > ! > However the port is in access mode (as it looks) and show int status shows > that clearly.. > ! > I have a question in my practice LAB that wants layer2 ports and interswitch > links to > trust cos and layer3 interfaces to trust DSCP. > ! > Am I not right to trust cos on the phone port ? > even though it seems access it is sending COS layer2 tags on the packets > right ? > > Another bonus question if the phone didn´t have the switchport voice vlan > but only a access VLAN it would sit on. Would that still be mls qos trust cos > ? > > regards. Kristjan > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
