Wired Intelligent Edge

Hi guys,

I am trying to set up QoS for voice VLAN in my Aruba switches. I know there are a lot of QoS options but it's quite confusing.

I have VLAN 40 for VoIP, and hard phones connected directly to switch ports, and they don't share those ports with PCs. PCs and laptops are connected to differents ports. What would be the way to configure my switches to prioritize the voice VLAN?

I have read some related HP switches posts, and I think the configuration would be something like this:

vlan 40

name "VoIP"

voice

untagged 1-10

Is this correct? I think I have to make the ports untagged because the phones are connected directly to the ports and don't share the ports with PCs, but I am not sure if in this way the phones tag the traffic or not.

What does the "voice" command exactly do?

Is there any other command I have to apply to enable QoS on the switches?

Regards,

Julián

If you want the voice vlan to forward the traffic based on QoS priority, you would tag the phone port to the vlan.  The switch would then forward all traffic that is received inbound at the received priority.

If they are untagged, the switch would forward all traffic on that vlan at normal priority.

Or you can change the priority of traffic on that vlan using the command "vlan <ID> qos priority <#>"

Hi Justin,

Let's say the phones tag the traffic. My configuration would be:

vlan 40

name "VoIP"

voice

tagged 1-10

What does the "voice" command exactly do?

Is there any other command I have to apply to enable QoS on the switches or it is enough with that configuration?

Regards,

Julián

Basically when you configure the vlan as a voice vlan, it can then separate the voice traffic from data traffic.  When you configure it as a voice vlan, the switch then will know that the vlan will be set aside for voip traffic and send that information via LLDP and CDP to voip supported devices.

By default, our switches have a queue mapping on the ports.  So when you tag the phone ports in the voice vlan, whatever priority the phone is "tagging" the traffic with, the switch will honor based on its bandwidth configuration.  You can verify the default config by running the command "show bandwidth output".

Ex:

Aruba-Stack-3810M(config)# show bandwidth output 1/20

Outbound Guaranteed Minimum Bandwidth Percentage

Port Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
------ ------ ------ ------ ------ ------ ------ ------ ------
1/20 2 3 30 10 10 10 15 20

If you desire the weighting to be different, there's a lot of commands to granularly set the qos either at the port or by traffic classifier/policy. 

To set at the port, we can adjust that at the vlan either by changing the queue weights or assigning all traffic on the vlan to a specific priority, like the command I shared earlier "qos priority #" or you can set by DSCP "qos dscp <value>" in the vlan.

Hi Justin,

Thanks for the interest. Then I understand we don't need any additional command to enable QoS on the switches as by default they have a queue mapping on the ports as you said.

Furthermore, with the "voice" command you say what VLAN ID the phones have to use to tag their. About the priority 802.1p value, does the "voice" command say any value to the phones to use or they put a priority value independently? If I remember well Cisco IP phones tag their traffic with priority 5 (EF) by default.

I have seen in the configuration guide the mapping is like this:

Then let's say the phones tag their traffic with priority 5, then based on your previous command "show bandwidth output 1/20", will the voice traffic get at least 10% of bandwitdh when there is congestion on the network?

Regards,

Julián

Yes, If you look at the queue config and the port queue weighting:

Aruba-Stack-3810M(config)# show qos queue-config

Egress Queue Configuration

Number of Queues : 8
Traffic Template : default-tcgt

802.1p
Queue Priorities
----- ----------
1 1
2 2
3 0
4 3
5 4
6 5
7 6
8 7

Aruba-Stack-3810M(config)# show bandwidth output 1/20

Outbound Guaranteed Minimum Bandwidth Percentage

Port Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8
------ ------ ------ ------ ------ ------ ------ ------ ------
1/20 2 3 30 10 10 10 15 20

Anything that comes in the switch with p5 is guaranteed to get 10% of the bandwidth by default.  That can be changed, but by default that's how it operates.  The voice command indicates to the switch that the vlan will be used for voip traffic and to send info to voip devices.

I forgot to post where you can find this in the manuals, it looks like you're already there, but just in case:

Voice VLAN info starts on page 48 of the Advanced Traffic Management Guide - https://support.hpe.com/hpsc/doc/public/display?docId=a00038722en_us

QoS info is later on page 249 in the same manual.

Hi Justin,

About this:

The voice command indicates to the switch that the vlan will be used for voip traffic and to send info to voip devices.

What kind of info is sent to the VoIP devices? I can't find the "voice" command anywhere, even in the guide. I have read that in HP Provision switches the voice command does the following:

- enables LLDP-MED
- sets 802.1p to 6
- sets DSCP to EF, and
- transmits the Vlan ID to the end device.

Do you know if that is correct? Does it apply to Aruba switches?

Thanks for your patience,

Julián

The voice vlan ID and port information is sent via LLDP or CDP to the voip devices.  The voice command designates the vlan as a voice vlan.

If you look at the LLDP-MED section of the management and config guide (pg 330 - https://support.hpe.com/hpsc/doc/public/display?docId=a00038741en_us), you can have those settings automatically applied by configuring it in the voice vlan.  You will still need to manually configure those settings in the voice vlan. 

By default, the voice vlan will honor whatever 802.1p bit is on the packet, if you need to change that, you can run the following command from the voice vlan context:

Aruba-Stack-3810M(vlan-40)# qos priority
0
1
2
3
4
5
6
7

This will set all traffic on the voice vlan to use the manually set priority bit.

With DSCP, by default, ef traffic will use p7:

Aruba-Stack-3810M(config)# show qos dscp-map

DSCP Policies

NOTE: The policies shown below are not currently enabled. Use the
'qos type-of-service diff-services' command to apply DSCP
policies to inbound traffic.

DSCP CodePoint DSCP Value 802.1p tag DSCP Policy name
-------------- ---------- ----------- --------------------------------
000000 0 0 cs0
000001 1 0
000010 2 0
000011 3 0
000100 4 0
000101 5 0
000110 6 0
000111 7 0
001000 8 1 cs1
001001 9 1
001010 10 1 af11
001011 11 1
001100 12 1 af12
001101 13 1
001110 14 1 af13
001111 15 1
010000 16 2 cs2
010001 17 2
010010 18 2 af21
010011 19 2
010100 20 2 af22
010101 21 2
010110 22 2 af23
010111 23 2
011000 24 3 cs3
011001 25 3
011010 26 3 af31
011011 27 3
011100 28 3 af32
011101 29 3
011110 30 3 af33
011111 31 3
100000 32 4 cs4
100001 33 4
100010 34 4 af41
100011 35 4
100100 36 4 af42
100101 37 4
100110 38 4 af43
100111 39 4
101000 40 5 cs5
101001 41 5
101010 42 5
101011 43 5
101100 44 5
101101 45 5
101110 46 7 ef
101111 47 5
110000 48 6 cs6
110001 49 6
110010 50 6
110011 51 6
110100 52 6
110101 53 6
110110 54 6
110111 55 6
111000 56 7 cs7
111001 57 7
111010 58 7
111011 59 7
111100 60 7
111101 61 7
111110 62 7
111111 63 7

To change the dscp value that the voice vlan would use, you would run the command, within the voice vlan context:

Aruba-Stack-3810M(vlan-40)# qos dscp
<000000-111111> The DSCP codepoint in binary format.
<0-63> The DSCP codepoint in decimal format.
af11
af12
af13
af21
af22
af23
af31
af32
af33
af41
af42
af43
ef
cs0
cs1
cs2
cs3
cs4
cs5
cs6
cs7

Does that help?

Hi Justin,

One more question, is the command "qos type-of-service diff-services" needed? According to my Aruba SE it is

https://community.arubanetworks.com/t5/Campus-Switching-and-Routing/ARUBA-SWITCH-AND-IP-PHONES/td-p/309405

Regards,

Julián

If you want the switch to prioritize QoS traffic based on DSCP rather than IP-Precedence, then yes.  By default it uses IP-Precedence.

Hi Justin,

But doesn't the switch prioritize traffic based on 802.1p rather than DSCP or IP-Precedence?

Regards,

Julián

Sorry for the misunderstanding, yes it proritizes based on .1p, so if you want it to do dscp, you would run that command.

"Basically when you configure the vlan as a voice vlan, it can then separate the voice traffic from data traffic."

This happens with any VLAN. When any VLAN is tagged end-to-end with a non default QoS value, it is treated differently than the default value traffic. Other than the LLDP expanded functions, is there ANY benefit to priority handling? Example:

VLAN 100 (voip): tagged on the access port, tagged on the uplink, QOS priority value customized on the switch to be higher than the data VLAN that is default.

VLAN 200 (voip): same as above, but with the "voice" classifier on the VLAN.

What is the difference here, if any, in relation to these two VLANs setup for voip traffic? It seems to me there is none, save for the expanded LLDP features enabled by the voice setting. Everything in Aruba documentation says to use the voice classifier for voip vlans, but it doesn't get into detail on what this actually does. I'm curious what the purpose of this even is.