Configuring Auto QoS Cisco 4506 - For access vlan

[ITexpert]

Hello Guys,

My Panasonic VoIP  phones does not support the cdp or lldp, so i just connect that phones in Access vlan.

this is my config :

int g3/42

switchport mode access

switchport access vlan 14

exit

I want to configure QoS for this vlan , Purpose of doing this is to get Phones traffic more priority than other traffic.

Thanks

[Georg Pauwen]

Hello,

below is a sample configuration for voice QoS for non-Cisco phones:

Switch# conf t
Switch(config)# int range fa0/0-18
Switch(config-if-range)# mls qos trust dscp
Switch(config-if-range)# auto qos trust
Switch(config-if-range)# priority-queue out
Switch(config-if-range)# spanning-tree portfast
Switch(config-if-range)# end

[ITexpert]

Hello George,

According to my knowledge, we have to classify , mark, put policies to accelerate traffic. There is something cos value at L2 and DSCP L3 value which differentiate the traffic to pass from queues so these things will work. 

which value cos or dscp value my phone traffic will get to prioritize ?

Does both ingress and egress traffic get prioritize ?

How I will verify the QoS, In times of congestion.

I even dont know what cos values my phones are giving to packets. Panasonic manuals do not define anything about it.

Thanks

[Georg Pauwen · Accepted solution]

Hello,

the 4500 only let's you police when you use class maps, which is not a good idea when it comes to voice traffic. So you are left with queue and buffer tuning, which is pretty much the same that auto qos does for you.

The Panasonic phones have to my best knowledge all DSCP defaults at 0, which means you can set them as you like. If you set RTP to DSCP 46 and SIP to 24, you should be fine with the config I posted earlier. You can verify what you have configured with the command 'show qos interface interface-id'

[ITexpert]

Hello Guys,  @Richard Burts @Reza Sharifi @paul driver  @Deepak Kumar @Peter Paluch

As my phones are in access vlan, because they dont support lldp or cdp. so Voice traffic is not tagged.

So which command i will use to mark their traffic(RTP) for dscp 46.  Please explain with commands ?

After marking the port traffic with dscp 46,  I just have to use the previous mention commands ?

Thanks

[Georg Pauwen · Accepted solution]

Exactly. You have to manually mark the voice traffic as mentioned, then use the commands as indicated...

[ITexpert]

Hello George @Georg Pauwen

After configuring this commands (auto qos voip trust,  qos dscp 46, qos trust dscp )on one of the phone port , I got this info 

213-FF-SW-02-EHGNA#sh qos interface g5/23
QoS is enabled globally
Port QoS is enabled
Administrative Port Trust State: 'dscp'
Operational Port Trust State: 'dscp'
Trust device: none
Default DSCP: 46 , Default CoS: 0
Appliance trust: none
Tx-Queue Bandwidth ShapeRate Priority QueueSize
(bps) (bps) (packets)
1 31250000 disabled N/A 260
2 31250000 disabled N/A 260
3 33000000 33000000 high 260
4 31250000 disabled N/A 260

Is it the Ideal ?

Now how to verify that this high priority is carried by trunk ports till firewall ?

Do we need to implement any commands at trunk port ? 

Thanks

[Joseph W. Doherty]

BTW, 4500 QoS features vary per supervisor.

"I want to configure QoS for this vlan , Purpose of doing this is to get Phones traffic more priority than other traffic."

Priority where (vs. other traffic)?

If your VoIP devices always have their own edge port, and if all your traffic is on the 4506, you likely don't need to prioritize the VoIP traffic. If your VoIP traffic shares links/ports with other traffic, that's where you may need QoS. Also BTW, since your VoIP phones don't use CDP or LLDP, ideally you should try to validate that it's a phone using the VoIP edge port, or if that's not possible, you can at least insure the port doesn't accept more than a VoIP phones maximum bandwidth.

[ITexpert]

Hello @Joseph W. Doherty 

I dont have any other device on edge device but and my phone is only device which is connected in access mode to port.

lets say 4506 have 200 devices out of which 40 phones are connected, so i just want that phones traffic when passing through the trunk port exit first as compared to other traffic and also enters first when it arrives on trunk port .

then also same thing from core switch to firewall.

please advice ?

Thanks

[Joseph W. Doherty]

". . . so i just want that phones traffic when passing through the trunk port exit first as compared to other traffic . . ."

Alright, for that you insure QoS is enabled, queues are defined with different priorities, one usually setup with PQ for real-time traffic like VoIP bearer and traffic is directed to the correct queue (often based on DSCP markings). (Cisco's SRND QoS v4 manual, has examples for different platforms, 4500s might be included).

". . . and also enters first when it arrives on trunk port ."

That's rarely done. Not all platforms support it. Even those that do, it may not work as you hope. Generally you prioritize on "other side's" egress.