QoS Features In Small Routers

SOHO users like myself are unlikely to have high-end networking gear supporting their home office setups. My initial experience with VOIP over broadband involved using Vonage and a Linksys BEFSR-41 broadband router. At the time Vonage was the leading phone-over-broadband service and the BEFSR-41 was the leading SOHO router.

It helps to frame this up in time. I used Vonage back in 2002. At that time Vonage was providing customers with a Cisco ATA-186 analog terminal adapter as the device to bridge the network to a couple of FXS jacks. The ATA 186 was the very first widely deployed ATA.

Cisco ATA 186 Analog Terminal Adapter

The Cisco ATA 186 is a single function device. As such it had very basic networking features. It could assign DiffServ TOS tags but relied upon the upstream network devices to manage traffic priority. This is typical of many low cost ATA devices even today.

Some time later Vonage shifted to providing a Motorola ATA device. This new device had the added feature of inserting itself into your network between the router and the rest of the LAN. Positioned in this manner it could itself ensure that the VOIP traffic received priority. This type of hardware is now the more common way that consumer phone-over-broadband companies address the unknown network circumstances of their customers.

The combination of the ATA 186 and the Linksys BEFSR-41 ultimately proved troublesome. Actually, they worked well enough together, but any other network activity could potentially interfere with the VOIP traffic causing choppy sounding calls. This was especially likely to happen if I had Outlook connected to my employers VPN. Outlook could easily saturate the outbound side of the DSL and the VOIP calls would suffer. The BEFSR-41 simply provided no mechanism to prioritize one sort of traffic over another.

After suffering with this problem some time, I found that Linksys had released a new router with built-in QoS features, the BEFSR-81. Since I had been happy enough with the first Linksys device until the VOIP troubles I bought the newer one immediately.

Linksys BEFSR-81 router with QoS features

The BEFSR-81 provided two means of traffic management; by physical Ethernet port, or by TCP-IP protocol and port.

QoS settings menu for Linksys BEFSR-81 router

It was a simple matter to put the Cisco/Vonage ATA on port 1 of the router and assign that port the highest priority. This took care of my QoS issue as long as I used Vonage.

As to its internal workings, according to Linksys literature the BEFSR-81 provides, "QoS Capabilities Based on IEEE 802.1p and IP TOS/DS Greatly Reduces the Chance of Data Loss Based on Weighted Round-Robin (WRR)"

The port based QoS feature is a little too simplistic to effectively support an Asterisk server as it doesn't allow you to assign QoS to a range of ports as required for SIP media. You can see in the screen shot where I had this setup for SIP signaling (port 5060) and IAX2 (port 4569.)

There was a period where Linksys let firmware development for the BEFSR-81 lapse. At that point the current firmware release that I tried had a serious bug that caused the device to lock up with startling regularity. At the time Linksys didn't seem at all interested in providing a resolution even though the fault was well known on public forums like Broadband Reports. This motivated my eventual migration to m0n0wall.

It is interesting that the BEFSR-81 remains a current product as of December 2007. Its cost/feature combination makes it in some ways it is an ideal device for non-technical SOHO users.

Tags: m0n0wall, VoIP,

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