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The VoIP vital signs

01 Feb 07

Performing a network health check - things to consider before deployment.
Businesses combining voice and data traffic are no longer breaking news - but make no mistake – integration can still be a major operation. Advantages are great, but work on the arteries of your client’s business demands thought, precision and care.
* Pre-op exam
For years companies have been accustomed to perfect clarity in their calls and slips – even a second’s disruption in an hour long conversation – may be interpreted as a serious flaw. An adequate ‘pre-op exam’ is vital.
This assessment should happen at the point of sale – before presenting a solution to a client – so patients know the cost before going under the knife.
Start at the beginning: assess satisfaction and experience with calls. Whilst a hard look at the network is essential, soft areas deserve attention too. What does the client want? Who is responsible? What domains are affected?
It is important to know the number of users, number of calls in peak periods and maximum possible at anytime. The resulting information can be used in a VOIP Call Flow Diagram - a plan showing bandwidth requirements.

* Finger on the pulse
Now to look at how the client’s system operates. The idea of VoIP assessment is to judge if existing networks are capable of delivering calls. Most are not designed to, so upgrades are usually necessary.
Take an inventory (configuration assessment) of all devices and review key parameters needed to support VoIP. Identify switches, routers, firewalls and links, and record configurations and firmware versions.
Monitor utilization of the network to verify capacity needed for additional VoIP traffic. Focus on WAN, determine CPU, memory, and link utilization include other network devices.
Identify delays, network bottlenecks, measure data loss and jitter, and add simulated traffic to determine quality that users can expect with a current setup (see ToolBox below).

* Alternative remedies
So you checked the network’s health and assessed its fitness to carry voice – but must the customer experience a costly nightmare of upheaval and product replacement? Always consider alternatives.
Most small businesses have a switch directing LAN traffic. Since within a Switch communication is point to point, its replacement with a bigger and beefier version at considerable cost is not always economic.
Frequent justification for such expenditure is security – stopping malicious software interfering or infiltrating the voice server. This could be prevented with a firewall between the existing switch and the voice server and by using VPNs to secure voice traffic.
Most IP Phones need power – so a Power Over Ethernet (PoE) switch or PoE injector could power such hardware, connected to the existing switch via a firewall (see diagrams below).

* Information flow
When large amounts of data travels across a network, traffic may be delayed by congestion and limited bandwidth - particularly in WAN Networks. Quality of Service (QoS) assigns priority tags to guarantee voice data is transmitted in real-time. 
 Modern switches offer 100 Mbit/s or even 1000Mbit/s capacity in LANs. If the highest quality voice call is 80kbs then - depending on Network utilisation - QoS may not be needed. Client’s network devices must support this feature – perhaps upgrading isn’t cost justifiable.
Look at how the business intends to use its network and see what system fits best. For instance, if a business requires a flexible solution for PC-based workers across locations, there is a strong case for software PBXs running embedded in the existing Network operating system, bringing remote users into a single system.
IT Net World Director, Andy Egli, says that “by understanding a client’s needs it’s possible to develop a solution that is both technologically proficient and cost-effective. Look at what the business has, see what you can reuse and make the most of what is already in place. You don’t need to reinvent the wheel every time but a little creativity can go a long way.”