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Community Member

VoWLAN issues

I have 2 different SSIDs and on one I have applied WMM settings and profiles is platinium on WLC for that SSID. Some users using normal SSID and I am on 2nd for testing VoWlan through my laptop. I make a call through Cisco IP Communicator and after some time voice starts degrade. I enabled WMM ad hoc mode on my laptop and I suppose the should not be voice degradation in that circumstances. Any body has experience on deployement of VoWlan?

I have read the book  already so pls need experts opnions rather than books links.

16 REPLIES

Re: VoWLAN issues

what are your QoS settings? AP should be trust RSVP, WLC should be trust CoS, and all switch trunks CoS. from the WLC under the QoS config, the 802.1p should be set to 6.

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Community Member

Re: VoWLAN issues

We want to implement Cisco IP communicator for laptop user, so thay can use IP Communicator for call rather than hard phones. But as you know hard IP phones mark the appropriate COS value for voice but how I can check whether my laptop sending Voice packet as 802.11e marked to the AP. Any idea and pre implementation plan. By default laptop has only one que and send Wireless traffic using DIFS but WMM enabled clients 4 Queues and send Voice packets using AIFS.

Need expert opinions.

Community Member

Re: VoWLAN issues

WLC has Platinuim profile configured. Auto QOS trust is enabled on Switch interfaces. APs conncted to Access ports. and switch to WLCs are trunk ports.

Re: VoWLAN issues

As per your setup, you second WLAN doesn't have any WMM config, hence the data coming out of your laptop will not get VOICE QoS.

Thanks

NikhiL

Re: VoWLAN issues

Oh Qos... Where is Nick! Nick is the man when it comes to QoS.

Let me see if I can clarify a few things. And I'm 99% sure this is correct. QoS is one of those things that causes a lot of confusion because how frames are marked in the tunnel and how they relate to wired side and if its up or down stream.

Your client (laptop) still needs to mark its frames with the proper QoS markings (CoS). You could sniff the air and see what the frame markings are to and from the client. 

Simply configuring a WLAN as WMM (say voice for example) doesn't guarantee its marked as EF. It only says, that UP TO EF is allowed.

If your laptop marks your traffic as say best effort (silver) even though you have WMM enabled and your WLAN is marked as Platinum, your frames are still BE. Why, because that's what the client marked them as and the AP / WLC will trust accordingly.

Thats my understand ...

"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
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Re: VoWLAN issues

Piggy backing George, the lowest Qos value will be taken into consideration .

Thanks

NikhiL

Community Member

Re: VoWLAN issues

What I need is I am not sure that my laptop is marking voice packet or not, and I enabled Ad HOC mode WMM so is that enough to enable WMM Queing? How I can verify my laptop sendind Tagged packet with 802.11e, which tool will help me. I am using windows 7 enterprise and don't wana buy USB device based paket sniffer. Any idea you can give me.

Bronze

Re: VoWLAN issues

Did you configure the AP switch port to trust DSCP?

Community Member

Re: VoWLAN issues

Yes I did this too, I read the Cisco VoWLAN design document. I want to implement Cisco IP communicator based VOIP and video both so the users can do voice or video call within network but problem is just WMM enable is not enough when using laptops. Application must mark the appropriate DSCP value for VOICE and Video and the OS will be responsible to forward to wireless interface to send towards the AP.

What is my problem is I don't have any tool which can help me to figure out that my laptop is doing the required marking and how I can further verify that WMM is enabled on my windows 7 machine. Do any body have idea how can we test and implement IP communicator based VOIP in organization instead of useing hard cordless IP phones.

Community Member

Re: VoWLAN issues

You could use wireshark to sniff the packets, it is free and very easy to use.... Download it at www.Wireshark.org

I hope this help you

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Community Member

Re: VoWLAN issues

I actually has wireshark, but to capture wireless beacon frames through wireshark, It requires wireless USB device for windows machine. I dont have any other way to verify that is the Voice frame tagged properly for QOS over wireless medium.

VoWLAN issues

All you need to do is capture the WLC port(s)/Channel.  then you look at the header to find the ip address of the laptop.  There is a setting in there to allow you to see into the CAPWAP header(as long as you are not using DTLS encryption).

you will then be able to see the CAPWAP marking, as well as the inside packet mark, and see if the packet has QoS or not.

HTH,

Steve

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Community Member

VoWLAN issues

Can you explain this how I could do that?

Re: VoWLAN issues

under the preferences there should be an option for CAPWAP.  What you need to toggle used to be called swap frame control.,

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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
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