Solved: QoS Question

angel-moon · ‎09-30-2015

Hello,

I have run into a 3rd party SIP phone and had a questions about QoS. These phones mark packets with Class Selector 3 (CS3) decimal 24. If I am using AutoQoS on the switches and standard QoS that recognizes Cisco Voice Packets with their tagging are the packets from these phones going to be given priority just like the Cisco phones? My preliminary research indicated that they will but I wanted to be sure.

Thanks. All replies are rated.!

Mark Malone · ‎09-30-2015

Hey If you want to be certain you could mark the port the phones connected into rather than allowing the source device set the marking, that's fine for Cisco as we know they are ef46 and will be prioritized but you want to make sure that any phone on the network gets this priority as its rtp traffic , I would say your good but I would confirm with a span session on the actual sip phone and see what exactly hes sending, you should see more than call signalling

with layer 2 ports autoqos or mls usually you trust the port with either mls qos trust dscp/cos or auto qos trust dscp/cos depending what your switch supports and let the phone mark from source as recommended , in your case you could also try make the port set the marking for these phones like mls qos cos 5 then on your uplink have mls qos trust dscp as your switch will re-map cos-dscp usually with this once mls qos is enabled globally ..mls qos map cos-dscp 0 8 16 24 32 46 48 5

dscp 24/26 which is cs3 or af31 is only call signalling you need to still make sure its prioritized with EF, if you wireshark the port the SIP phone may already be sending that too

anyway this doc may help you it has some good examples

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/qos/configuration_guide/b_qos_152ex_2960-x_cg/b_qos_152ex_2960-x_cg_chapter_011.html#d25414e745a1635

View solution in original post

Mark Malone · ‎09-30-2015

Hey If you want to be certain you could mark the port the phones connected into rather than allowing the source device set the marking, that's fine for Cisco as we know they are ef46 and will be prioritized but you want to make sure that any phone on the network gets this priority as its rtp traffic , I would say your good but I would confirm with a span session on the actual sip phone and see what exactly hes sending, you should see more than call signalling

with layer 2 ports autoqos or mls usually you trust the port with either mls qos trust dscp/cos or auto qos trust dscp/cos depending what your switch supports and let the phone mark from source as recommended , in your case you could also try make the port set the marking for these phones like mls qos cos 5 then on your uplink have mls qos trust dscp as your switch will re-map cos-dscp usually with this once mls qos is enabled globally ..mls qos map cos-dscp 0 8 16 24 32 46 48 5

dscp 24/26 which is cs3 or af31 is only call signalling you need to still make sure its prioritized with EF, if you wireshark the port the SIP phone may already be sending that too

anyway this doc may help you it has some good examples

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/qos/configuration_guide/b_qos_152ex_2960-x_cg/b_qos_152ex_2960-x_cg_chapter_011.html#d25414e745a1635