QoS for voice traffic

[Inge_Suzzy]

How can i configure QoS without using voice vlan? not all of my switches support it.
It is simple?

I only have 2 vlans, my ports are hybrid, vlan assigned for ip telephony is tagged and vlan for data is untagged.
Lately we have problems of dropping calls, i don't think it's a qos factor, but my client think that's the problem

the models that i have 4800G, 4500G

[Michael A. McKenney]

You could put the phones on their own switch off a separate port of a router or firewall.  You don't need a highend switch.  A simple 1 Gbps switch would do since most voice traffic is 56kbps.  

[manuel.bitzi]

The best way is to priorize the whole vlan. i.e.:

traffic classifier MatchAny operator and
 if-match any
#
traffic behavior SetVeryHigh
 remark dscp cs6
 remark dot1p 7
 remark local-precedence 7
qos policy PrioVeryHigh
 classifier MatchAny behavior SetVeryHigh
#
qos vlan-policy PrioVeryHigh vlan 9 inbound

br

Manuel

[Inge_Suzzy]

thank you, I will try that configuration

And last question, I did an investigation regarding this fact of qos, I found that switches has a default qos treatment, I captured some traffic of a mirrored port on a switch, to see if the packets were prioritized, and I see that all packets of telephony says 0xb8 DSCP 0x2e and all traffic of data says 0x00 DSCP 0x00 and search this and found that it's the correct treatment for an IP Telephony scheme.

My question is this, When is necessary implement some technic of qos?

Is it necessary when you have a segmented LAN, without restrictions of bandwidth or some policy of use?

[Michael A. McKenney]

You use QoS on Voice, when the phone calls are choppy or dropping due to connectivity issues.  On slow internet connections, I usually put the IP phones on their own switch.   A inexpensive switch is less expensive than wasting time on QoS rules or configuring an isolated VLAN. 

[manuel.bitzi]

Hi Inge

the voip packets are marked with DSCP 46 by the phone, but the switch will not care about this. activate "qos trust dscp" on each switchport. that will help.

br

Manuel

[Inge_Suzzy]

But on the manual says that, by default mode 4800G and 4500G has 802.1p precedence trust mode, for tagged packets, its 802.1p value is used to map to local and drop precedence and for untagged packets, the port priority is used to map to local and drop precedence and the por priority is the default.

And it's extrange for me that calls are drop even when there are no other traffic, I do that test on night,

And this command has to be configure and all switches and ports,on the LAN, is it?

 I know  qos it's  required for voip but if i have switches that work on giga the end devices work at giga and a call consume 80kbps, and the data transfer is also over kbps, and the lan  it's not rate limiting and the switches have a very good througput, i do not understand very well when to use qos, I think it could be the problem if also the end users access youtube, share autocad doc's or something that consume a great amount bandwidth, but that doesn't happen.

Even the simplest network has to had qos and not only vlan segmentation, it doesn't matter the switch capacity, is it?

Why if it is so necessary, it is not enable by default =s

[Michael A. McKenney]

No traffic?  I bet a network scanner would find SQL, Email, DNS, and other traffic on your network.   On my A5800 switches, my 5 IP phones are in the trusted VLAN with my users and servers.  No issues.  Switch performance can handle all the traffic and not drop a packet. 

QoS and Voice VLAN are necessary because a drop packet on a computer is no issue.  It just resends.  A dropped packet on a phone is detected as a hang up.  At home, my Sprint Airave device for my cell phone has QoS priority 1 on my Dlink router so I don't drop my calls.  Airave is a mini cell tower that routes my calls over my internet connection back to a Sprint NOC. 

You have two choices. 

1.) Create a separate VLAN for phones only and put the network cable to your phones on this VLAN.  Keep it isolated from the other VLANs.  

2.) Install an inexpensive switch to handle the phones.

My phone vendor usually just puts in a separate switch for VIOP.  This way you just plug and play.  No need to program a VLAN or QoS.  It is isolated.   Any old switch would probably due. 

[Vince-Whirlwind]

" calls are drop"

You mean the call ends? That's not a VoIP issue. VoIP uses a connectionless protocol so packets are fire-and-forget. If voice packets fail to reach the other end you get call quality issues but you do not get calls dropping.
If calls are dropping, that would indicate a signalling problem, and/or a problem with the call controller.

[Vince-Whirlwind]

---

@michael a. McKenney wrote:

  A dropped packet on a phone is detected as a hang up.   

---

This is incorrect. A dropped voice packet has no effect whatsoever on call setup or tear-down.

Using a seperate switch is also not very good advice - some telephony providers do this because their knowledge of networking is very poor and they don't know how to manage two VLANs. The net effect is double the infrastrucutre, inefficient use of structured cabling, inefficient use of power and rack space.

The OP already has two VLANs, and the endpoints are already adding the correct DSCP value to the VLAN tags.
As per previous advice, just add the qos trust command to the interfaces.

Voice quality issues: check our your QoS.
Calls dropping: nothing to do with your network - flick the problem to the telephony provider.

[JNuttall]

I Had an issue with the Snom 300, handsets.

The Provider and the, deveopers were blaming the PBX and the network, untill i proved that the calls were being droped by the SIP Protocol on the fact the recever switches were faulty. once we RMA ed the handsets we didnt have any issues what so ever.

the sip protocol, and there are others for signaling requires an explicit hang up, loss of data packets wont drop the call.

[KalebSturgill]

I know this is an old topic, but I would like some help with a problem I am having with my HP 5130 EI

Here is the version information....

____________________________

HPE 5130-48G-PoE+-4SFP+ (370W) EI JG937A with 1 Processor
BOARD TYPE: 5130-48G-PoE+-4SFP+ EI
DRAM: 1024M bytes
FLASH: 512M bytes
PCB 1 Version: VER.B
Bootrom Version: 145
CPLD 1 Version: 002
Release Version: HPE 5130-48G-PoE+-4SFP+ (370W) EI JG937A-3115-US

_______________________________

I tried applying the same config you recommended to make a whole vlan a priority and the policy is showing failed when I use a "if-match any" in my traffic classifier.

See the output below of the display qos vlan-policy 30

display qos vlan-policy vlan 30
Vlan 30
  Direction: Inbound
  Policy: PrioVeryHigh
    Classifier: MatchAny (Failed)
      Operator: AND
      Rule(s) :
        If-match any
      Behavior: SetVeryHigh
        Marking:
          Remark dscp cs6
          Remark dot1p 7
          Remark local-precedence 7

On the classifier line it is showing "MatchAny(Failed)"

Do you know why this would be showing as failed? I even tried removing and readding the policy and re-applying it and it still comes back as failed.

Thank you for your help.

[KalebSturgill]

I found from the logs it was saying there was a conflict in the remark.

I removed the local precendence remark 7 and now it is applying successfully.

Thank you