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Beginner

7921g and wlc 4404 oneway voice problem

Hi,

I have a metwork with 35 AP 1242 (only 2.4ghz band) and 30 7921g.

I'm using a WLC 4404 version 4.2.61 7921G version 1.1.1, CCME version 4.1, AP IOS 123-7JX.

The coverage seems to be good and also the overlap.

The problem is: some times casually and also not walking we lost voice (one way o both way) for 10 or more seconds the call is still active. I tried to improve roaming, I have enable WMM support, DTCP and all the features racomanded on the wlc docs. I have analised RF interfernce with wy-spy and not seems to be relevant interference. The AP profiles are all in pass (if you check on the WLC) I can ping the CCME with a PC on the WiFi VoiceVLAN.

It very stange and a can't find a solution because the problem is not localised in an area. It is more evident when we have a conversation between 2 wifi phones.

I can't find a way to solve the problem.

Thanks

31 REPLIES 31
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Another idea would be to set it up using the a radios 5GHZ and see if the same happens this will show if its interference. There are alot fewer interference sources for a than b/g.

Just a thought

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It seems a good idea.

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That is not true. The 7921 can tx up to 17 dBm (50 mW) for 802.11b and up to 16 dBm (40 mW) for 802.11g and 802.11a. Yes the 7921 supports DTPC, so will use the closest supported txp power per the client power advertised from the AP.

But if you are using max power on the AP, then the max would be 100 mW for 802.11b and 50 mW for 802.11g and 802.11a.

I believe you are getting confused with the 7920 phone, which is end of sale. It had a default tx power of 20 mW and didn't support DTPC until firmware version 1.0(8), so would have to manually configure the tx power higher if necessary (i.e. 50 or 100).

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Beginner

HI,

Is ARP caching enabled on the WLC?

Goen

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Hi I think is enabled but I con't understand where check.

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Depending on the version you are running: telnet/ssh to the controller do a show network (summary) and look for

ARP Unicast Mode.......... Enabled

in the newer versions (5, late 4) it seems to be hidden.

FYI there is also a new 7921 firmware load (don't think this will reslove your issue, but you could try it)

Goen

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Goen, are you sure about the "ARP Unicast Mode Enabled"?

According to the 7921G deployment guide, it should be disabled

---------- Snip from 7921dply.pdf---------

When configuring your access points, use these guidelines:

• Set the QoS policy to “Platinum”.

• Enable WMM to enable QoS and the ability to use U-APSD.

• Disable DHCP address assignment required.

• Ensure “Aggressive Load Balancing” is disabled

• Ensure ARPUnicast is disabled

• Disable Peer to Peer Blocking / Public Secure Packet Forwarding (PSPF)

• Ensure Client Management Frame Protection (MFP) is set to disabled or optional

• Enable “Symmetric Tunneling” if Layer 3 mobility is enabled

When using 802.1x authentication, it is recommended to implement CCKM.

Note: If you have clients from other regions that will attempt to associate with the WLAN, then ensure that World Mode

(802.11d) is enabled.

The SSID to be used by voice clients can be configured to only apply to a certain 802.11 radio type.

--------------- Snip end ------------------

Also, in the Enterprise Mobility Design Guide v4.1, Chapter 2, ARP paragraph, it is suggested to keep it disabled to avoid ARP broadcast storms, which can lead to a DoS situation. This was a vulnerability in earlier versions of the WLC software.

It is even suggested to enable DHCP required on the WLAN in order to prevent exploitation of such vulnerabilities, but I am not aware of the full impact of this setting, since it is against the 7921 deployment guide instruction.

Anyway, we experience similar problems, WLC 4402, 4.2.130.0, with 7921G running 1.2.1.

Michael

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Depending on the version you are running: telnet/ssh to the controller do a show network (summary) and look for

ARP Unicast Mode.......... Enabled

in the newer versions (5, late 4) it seems to be hidden.

FYI there is also a new 7921 firmware load (don't think this will reslove your issue, but you could try it)

Goen

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Hi "g.rienstra", that is an incorrect statement about ARPunicast. If proxy ARP is enabled then ARPUnicast is disabled as I have put into the 7921G Deployment Guide. If you enable this, it may cause problems. Also battery life for the 7921 will not be optimal (80 hrs vs 150 hrs with standard battery if no proxy ARP support on the AP).

The "config network arpunicast disable" has been removed in 5.1, so proxy ARP will always be enabled.

I would suggest to use 5.1.151.0 as this also has TCLAS support.

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oepsss.... You are correct. I was looking at an old system (config) from a customer using Polycom wireless phones. the this statement is applicable.

My apologies.

Goen

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Hi all,

I have the same problem:

- 98 pc. 1242 (2.4, 5GHz)

- 5 pc.7921G (CP7921G-1.1.1.LOADS)

- 2 pc. WLC 4404 (4.2.130.0) with LAG to the

switch

- CCME 4.2(0), IOS 124-11.XW6.bin

Could it be, that the LAG is trying to "balancing" the RTP-Stream?

Greets,

Norbert

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We seem to have solved our problem.

Make sure your QOS is set correctly.

Set your AP on the switch to auto duplex speed 100. On the WLC on the switch auto auto.

Good luck

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Hi I hope I'm quite near a solution of the original problem.

I changed the authentication type to wpa/TKIP + ccmk and It seems working well.

Before I was using dinamic WEP with LEAP.

Bye

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FYI....there are no known issues on the 7921G side in regards to 802.1x+WEP using LEAP. Ensure you are using version 1.2(1) for the 7921G. We recommend 4.2.130.0 or later for the WLAN controller, preferably 5.1.151.0.

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Hi,

I can't find this issue, can you tell us what's the bugID ?

Thks.

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