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Wireless Issues when making a VoIP call using a Linksys PAP2 and an Apple Airport Extreme Router


Hey Everyone!

Thought I’d post this little technical issue to my blog in hopes that someone else in the world has had the same issue I’m having right now and perhaps share their solution :)

I have a Linksys PAP2 VoIP adapter (Firmware version 1.00.22) plugged into an Ethernet port on my Airport Extreme (Gig-E). I also have another Airport Extreme setup as a repeater in my home theater.

When I use my VoIP phone, my wireless clients internet connectivity slow to a crawl. While doing a ping to my gateway (10.0.1.1) I can see my response times become pretty erratic ranging form 50ms to 1600ms, with about 15% of the requests timeout.

I setup the PAP2 VoIP device with a static IP (10.0.1.5) and set it as the default host. My theory at the time was that since it was being NAT’d, the inbound UDP traffic was being transmitted across and flooding my wireless network.

This doesn’t seem to have fixed the problem. I experience this wireless slowdown on both my PC (Dell Precision laptop) and my Mac (PowerBook, MacBook) wireless clients.

Both my AirPort Extreme base stations are running the latest version of the firmware (7.2.1, I believe) and this issue does not happen to wired clients on my primary base station (where the PAP2 is plugged in).

Has anyone else experienced this problem or have any idea what could be happening? I’m hoping I’ll be able to locate a solution somewhere, but so far I haven’t found any resources online that would help.

Thanks!

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This entry was posted on December 15, 2007, 1:42 PM and is filed under Hardware, Internet, Networking. You can follow any responses to this entry through RSS 2.0. You can leave a response, or trackback from your own site.

  1. #1 by Mike on December 27, 2007 - 1:31 PM

    I suspect that the high packet rate of a VoIP call (20ms intervals for RTP) is chowning the wireless chipset on the airport. This is pretty easy to test, you can simulate a VoIP packet rate using a laptop on the wireless and then doing some simple ping tests to compare.

    # ping -i 0.02 -c 500 -q [router_ip]

    Most wireless AP’s are NOT capable of handling the high packet rate of VoIP calls. If you have SIP / QoS functionality turned on the Airport, I would turn it off. Anything that requires some sort of packet inspection is just going to slow down the packets. Hope that helps.

    Cheers!
    Mike

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