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New Member

7921 constantly dropping off the network

Currently running a 7921 pilot with 10 users (90 more phones waiting to be deployed) using WiSM 4.0.206 with approx 70 1010/1020 airespace ap's. Professional Site Survey.

The problem I have is the 7921 constantly drops off the network, saying things like 'leaving service area' or just periodically re-registering with call manager. I also have issues of 1 way audio.. but i think the main issue is the continual dropp off of the clients. I have tried the 7921 profile in many different ways, a-only, a-preferred, b-g only etc but still experience the problem!

The strange thing is I have 7920 working perfectly on the same wLAN..! I did however experience similar issues during the early firmware. I think 4.0-03-01 resolved 90% of the issues..

anyone any ideas?

  • Wireless IP Voice and Video
30 REPLIES
Cisco Employee

Re: 7921 constantly dropping off the network

Currently the AP1000 series 2.4 GHz radio has some issues sending beacons at the expected intervals. CSCsj02690

The 7921 uses beacons for connectivity status, where 7920 only uses probe responses from scanning.

If wanting to use AP1000, would advise to use 5 GHz.

Ensure arpunicast is also disabled, where proxy arp will be enabled. Can dow "show network" to check.

See 7921 Deployment Guide for more info @

http://www.cisco.com/univercd/cc/td/doc/product/voice/c_ipphon/english/wip7921/7921dply.pdf.

New Member

Re: 7921 constantly dropping off the network

Hi Michael

Many thanks for your reply, I'll look into the arpunicast and proxy arp items later. With regards to 5 GHz - we still experience the the exact same issues... I must admit, a couple of recent comments relating to the 1000 series ap's radios concern me!

Cisco Employee

Re: 7921 constantly dropping off the network

Have you tried with the AP1130 or AP1240?

New Member

Re: 7921 constantly dropping off the network

Unfortunately not. I may look into purchasing a couple of AP's however I would prefer not to go down that route if at all possible!

Cisco Employee

Re: 7921 constantly dropping off the network

I would suggest to open a TAC case to assist validating your deployment first.

New Member

Re: 7921 constantly dropping off the network

wie have the same exactly the same problem with cisoc 7921 phones (AP1020). Meaning that the phones are periodically re-registering with the call manager.

The point is, like you say, that the 7920 is working perfectly on the same environment.

We do have opened a cisco case (prio 2)but until know no result, exapt some recomendation abaut QoS;-)

so let us please stay in contact util we get red of this issue...

Cisco Employee

Re: 7921 constantly dropping off the network

What is the case #?

For now, would recommended to use 5 GHz only with AP1000 platform.

New Member

Re: 7921 constantly dropping off the network

Sorry for the delay in getting back... I have an open case already although we don't seem to be making too much progress. Just constant traces which are difficult to take as it requires (some) downtime... I'm at a loss to explain the issue, even when using 5GHz only we stil have exactly the same problem.

Cisco Employee

Re: 7921 constantly dropping off the network

If you are having issues w/ 5 GHz, then you must be encountering something different.

Would ensure your deployment is inline w/ the 7921G Design Guide.

Maybe you can try to disable WMM and see if that helps, especially if QoS markings are not preserved to the WLAN.

Can check the 7921 web page to see if DSCP markings are correct or not.

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