Archive for November, 2007

tech: how to avoid clobbering your VoIP traffic with your PC

I have Vonage at home, and have been happy with it. Both it and my cable ISP have been remarkably reliable. The only issue I’ve run in to is my limited upstream bandwidth: although I have 5Mbs of downstream bandwidth, I have only 350kbs of upstream bandwidth. In the past if I’m doing a big upload with my PC and trying to make a phone call at the same time, I can hear the other person on the phone but they can’t hear me: my PC is sucking up all the upstream bandwidth and not leaving enough for the VoIP call.

Since Vonage provided me with an adapter (Motorola VT2442), and I already have a Linksys WRT54G for wireless access in my house, there is a pretty easy solution for this problem. It doesn’t require any extra hardware or software, just some configuration.

I think Vonage may claim that their adapter automatically throttles PC traffic while you are making a phone call, but that doesn’t work for me. So I’ve had to do the following.

First of all, connect the Vonage adapter directly to your ISP. If you have a cable modem or DSL adapter, connect the ISP ethernet to the Internet port on the Vonage adapter. If the Vonage adapter was the only adapter you had, this would be the default configuration.

Second, connect the Linksys adapter as a downstream device from the Vonage adapter. Connect LAN port 1 of the Vonage adapter to the Internet/WAN port of the Linksys adapter. Now you have 2 chained firewalls. Connect all your computers to the LAN ports of the Linksys adapter. Do not plug any ethernet devices into ports 2 through 4 of the Vonage adapter.

Third, go do a speed test to see what your upstream bandwidth is. A quick Google search should find some decent ones, such as SpeakEasy, DSL Reports, or Run the test and see what your upstream bandwidth is. Mine is around 350kbs. You may want to try more than one to find the maximum values.

Fourth, check the VoIP bandwidth. This is determined by your call quality setting. Logon to the Vonage web site, select “Features”, select “Bandwidth Saver” and look at which setting is selected: 30, 50, or 90kbs. This is how much bandwidth you need to reserve for your VoIP traffic. I have 90kbs selected, so I’ll reserve that a just a bit more: 100kbs.

Fifth, login to your Linksys management console. My Linksys device has QoS (quality of service) support. On this particular device, under the “Applications and Gaming” menu is a “QoS” menu. It has an entry titled “Limit Upstream Bandwidth”. Set it to the value of the upstream bandwidth from the test minus 100kbs. So I set mine to 250kbps. And I clicked the “Enable” button and used the “Manual” setting instead of “Auto”. Don’t forget to click “Save Settings”. If you don’t have this Linksys model, poke around the menus of the device you do have and see if it offers similar function.

So what this does is limit upstream bandwidth for all devices connected to the Linksys (ethernet and wireless PCs) to 250kbps, reserving 100kbps of upstream bandwidth for VoIP calls. Yes, this does limit PC upstream traffic to 250kpbs at all times, even when a VoIP call isn’t running, but this is a decent configuration for the cost.

Lastly, go do a speed test again and see what the upstream bandwidth is. It should be the value you set in the Linksys, i.e. 250kbps. Now you have a 100kbs reserve for your VoIP traffic.

tech tips marcelk 18 Nov 2007 No Comments

entertainment: full-length episodes of “Car Talk” now online!

I had been listening to the podcasts that had only “the call of the week” highlight, but now the entire hour-long episode is online for free from NPR. Woohoo! Not only can you learn about car repair, but you can laugh out loud while you do it. This is one of my favorite shows on radio. Thank you, NPR. No more having to schedule my Saturday around the scheduled airtime. I’ll have to increase my contribution to my local public radio station.

cool stuff that doesn't cost much &entertainment marcelk 11 Nov 2007 No Comments