Tuesday, 22 December 2009

QOS on the Linksys WRT54G

If you use VoIP on your LAN network and the WRT54G as your router, it is very important that you become familiar with its QOS settings to maximize your VoIP quality by giving VoIP top priority over other data traffic through your router on its way to your ISP and the Internet.

To get started, login with your PC's web browser from one of the WRT54G LAN ports.  Typically, you will use 192.168.1.1  IP address.  By default, the User Name is blank (empty) and password is "admin".  I have modified my personalized login to require a secure User Name and PW.  You may have done the same for yours.

Once logged-in to the WRT54G, you will find QOS settings on the "Applications and Gaming" tab.  Then, click on the QOS section to view QOS settings.

As can be seen on the WRT54G QOS page , there are numerous ways of implementing QOS for your LAN.

Here are some  comments on how I have set my router QOS settings:
  1. Be sure QOS is set to "Enable".
  2. Upstream Bandwidth setting:   I believe Auto is the default.  However, if you know what your Upload Bandwidth limit is, as set by your ISP, or if you have measured your upstream bandwidth through a speed test service, you may want to set your upstream to Manual and match the speed setting to your known maximum upload speed (Setting it slightly less than your limit or measured value is advisable).  The reason for this is to ensure that your router's QOS efforts aren't in vain only to have your ISP Modem cause your VoIP data to bottleneck because you are pumping out a faster upload data rate than your ISP allows.  In my case, I have set my router upload limit to be much lower than my ISP upload limit (my reasons are beyond the scope of this post).
  3. Device Priority:   You have the ability to specify the MAC address of specific Ethernet devices on your LAN to be given specified priority levels.  For example, if you were using an IP-Phone on your LAN, you could specify the MAC address of that phone to be given highest priority because it is carrying VoIP calls.  Or, as I have done, I specified the MAC addresses of Linksys SPA2102 VoIP ATA's that I use for my VoIP calls.  However, it could just as well been a Linksys PAP2T ATA or some other brand of VoIP ATA.
  4. Ethernet Port Priority:  Another way to give specific devices a high priority level is to prioritize traffic by Ethernet Port.  The WRT54G is a 4-port router and can prioritize each port according to your specified settings.  For example, if I had a PAP2T on port-1, I would assign that port a High Priority status.
  5. Application Priority:  You can also set priority of specific applications running on your LAN based on ports required by those applications.  For example, I have configured Skype to use port 39700.  Therefore, through Application Priority, I have given Skype running on port 39700 a high routing priority through the router.  I have also set priority for SIP ports 5060 - 5063.  This way, if I am using my 3CXPhone softphone on my PC, its opened SIP ports will also be given a high priority routing through the router.  And, also because I use Google Talk, I have given it priority on ports 5222 and 5223.
  6. Wireless QOS:  Because the WRT54G is also a wireless router, it supports QOS over the wireless link as well.  If the PC connecting wireless supports Wi-Fi MultiMedia (WMM) QOS, then you will want to set the WMM Support to Enable.  For example, I also run the  3CXPhone softphone  on my laptop and have WMM support enabled on the laptop wireless card too.
Whether on not you use the WRT54G router, I hope this post provided you with some useful insight of how QOS can typically be implemented through NAT-Routers for your LAN devices.