VOIP phones and qos

carl_townshend · ‎01-29-2008

Hi all, when using say siemens voice phones, do they mark the dcsp or 802.1p tag ? and can switches nowadays read both ?

mchin345 · ‎02-04-2008

I think it depends upon your QOS setings and device implementaion. You can configure the switch to trust or override the traffic priority assigned by a IP phone.

carl_townshend · ‎02-12-2008

ok, so does the switch look at the dscp header? does it treat this as a tagged packet as i believe tagged means 802.1q, whereas the dscp header is in the ip payload part of the packet, so would the switch still treat this as a tagged packet .

please explain

carl_townshend · ‎02-17-2008

can anyone clarify on this

royalblues · ‎02-18-2008

Yes.. the new range of L2 switches are capable of reading the DSCP bits

Phone by defualt can set both the DSCP as well as the 802.1p values. You can configure your port to trust either the Cos or DSCP

DSCP is preferred as it would be end to end while with COS you would require COS-DSCP mapping

HTH

Narayan

b_ferguson · ‎05-30-2008

Carl,

Did you get your QoS setup properly for Siemens' phones. I have a customer with Siemens phones and can't seem to find documentation of the dscp values for the phones. Any help would be greatly appreciated.

Thanks,