The next level up from a personal home network is a Small Office Home Office (SOHO) network. The requirements change from a purely experimenter, low VoIP usage to one where the end user is expecting a higher quality of service (QoS). The end user wants a reliable voice connection at all times, basically because they are running a business from home and require a professional appearance. The budget is still low so some compromises are taken.
The SOHO is an interesting situation as there are a number of choices available with some that do not require hosting your own PBX:
Once, you reach the SOHO level, quality becomes an issue and the configuration and design of the network becomes of concern. Data traffic starts to interfere with the voice traffic causing poor audio quality, dropped calls and break-up. What can be done?
The first step is to identify the areas of the network where the bottlenecks are between data and voice traffic. The second step is to limit the traffic by separating the two as much as possible. Let's take a look at a typical SOHO network topology (drawing of the layout) which adds a separate Ethernet switch to provide more network connection than a standard wireless router.
Typical SOHO network
Congestion on the SOHO Network
The simplest and least expensive solution is to purchase another inexpensive Ethernet switch and separate the voice and data traffic. One switch for voice. and the other for data traffic. This moves the bottleneck to inside the wireless router where there are usually methods to set the priority of data and voice traffic.
Separate Voice and Data Ethernet Switches
A very important point is that even though there are two Ethernet switches, there is still only one network with one network address (ex. 192.168.1.0/24) that spans across both switches. This means that broadcast traffic from both switches will appear throughout the network.
Router Traffic Management
A lot of wireless routers provide traffic management and QoS through their web based GUI. The traffic management really only deals with outbound traffic. Priority can be given to voice protocols like SIP. The router recognizes the voice traffic and given the choice between sending out data or voice, it will send the voice first. Each router is different and its capabilities would need to be explored to see how it can manage traffic.
Aftermarket Router Firmware
There are several aftermarket router firmware upgrades that are both free open source and paid upgrades that can add more capabilities to your wireless router. The result is that your el-cheapo router gets a hit of steroids and provides features normally seen only on expensive enterprise class routers. One of these is DD-WRT which allows you to set priority based on the physical Ethernet port. You could set the port connected to the voice Ethernet switch as having priority over the data Ethernet switch's traffic. Aftermarket router firmware upgrades require a higher level of expertise and patience to get working correctly.
VLANs and QoS?
Instead of using two separate Ethernet switches, you can upgrade to a more expensive switch that features VLANs (virtual LANs). The physical switch is able to divide itself into virtual switches. These virtual switches appear as if they were separate physical switches as discussed previously and as separate networks with unique network addresses (ex. 192.168.1.0/24 and 192.168.2.0/24). QoS (Quality of Service) can be controlled and configured in both the switch and the router. This is a step up in cost and complexity and the network design is now moving closer to the Business Network.
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