typical config access port:
switchport mode access
switchport access vlan 5
switchport voice vlan 10
mls qos trust cos
mls qos trust device cisco-phone
mls qos vlan-based
config on vlan
int vlan 10
mls qos trust dscp
remap cos3 to DSCP x
remap cos 5 to DSCP 46
Q1) Will every cisco-phone 79xx automatically tag signalling traffic to cos 3 (skinny, H323,... dunno)and voice traffic to cos 5?
2) Or is it dependent on the cisco model
3)Or is class-map with ACL needed to classify signaling traffic and mark them in a policy map to cos 3? If yes, are there ACL templates for this
4) I've read this in callmanager guide for CCM 5.1
Cisco SIP phones get their DSCP information from the configuration file that gets downloaded to the device. The DSCP setting is for the device; whereas,
the SCCP phones can get the DSCP setting for a call.DSCP values get configured in the Enterprise Parameters Configuration window, and in the Cisco Unified CallManager Service Parameters Configuration window.
5)So this means for SIP phones: they'll use the DSCP value for voice and signalling as configured in the CCM? True/false
6) what means this part? whereas,
the SCCP phones can get the DSCP setting for a call.
Thank you very much!! I've no voice experience.
The CIPC will send out the correct values also, where this falls down obviously is if the PC is connected to the back of an IP phone as the 79XX phone declassifies all PC traffic.
So assuming the PC with CIPC is not going into the back of a phone the vlaues the CIPC application send out will be the correct COS values
no you should not need to use ACLs the trust cos should be sufficient and set the mapping as stated.
If you have a sniffer such as wireshark you can use this to confirm what DSCP values are being sent between phones.
But in summary the switch should forward the tags without problem (I assume its a Cisco)
1 and 2. Yes the phone tags the packets as required. COS 3 for signalling and COS5 for the voice stream. It is the same for all Cisco models as far as I know
3. You will ususally need to reclassify the packet where it hits a layer 3 or router junction. The layer 2 switches should forward the the tags and should also remap the cos-to-dscp values. (unless its the entry level 2950)
A show mls qos cos-to-dscp maps or similar should show you how they are mapped.
There should be no need for you to remap on the switch expect for the COS3 value. Old Cisco kit used to use DSCP value 26, the latest IPT kit uses DSCP value 24. I always remap this as the switch IOS is still programmed for the 26.
mls qos map cos-dscp 0 8 16 24 32 46 48 56
As for ACLs at the L3 junction the MLS qos should support this if not then you can use LLQ config to reclassify. Here is some config I have on a WAN router between 2 sites that also supports VC
class-map match-all VOICE-RTP
description VOIP Bearer Traffic
match access-group name VOICE
class-map match-all VOICE-CONTROL
description VOIP Control Traffic (SCCP, H225, H254, MGCP)
match access-group name CONTROL
class-map match-all VIDEO-CONF
description Video Conference Traffic
match access-group name VIDEO
description Set DSCP for VOIP Control, ICCS and Bearer Traffic
priority percent 33
set ip dscp ef
set ip dscp cs3
set ip dscp af41
ip address X.X.X.X 255.255.255.0
no cdp enable
service-policy output VOIP-QOS
ip access-list extended CONTROL
remark Match VoIP Control Traffic
permit tcp any any range 2000 2002
remark H323 Fast Start
permit tcp any any eq 1720
remark H323 Slow Start
permit tcp any any range 11000 11999
remark H323 MGCP
permit udp any any eq 2427
ip access-list extended VIDEO
remark Match Video Streaming Traffic
permit ip any any dscp cs4
permit ip any any dscp af41
ip access-list extended VOICE
remark Match the UDP ports that VoIP uses for Bearer Traffic
permit udp any any range 16384 32767
5. From my understanding yes they will use the same value most likely COS5 they recive this instruction from the config file downloaded from the Callmanager
Hope this Helps