Determining VoIP Quality of Service

Though the economy may be slowing, VoIP is increasing in popularity, as is video. Cutting communication costs is a great way to enhance your bottom line, but it isn’t worth much without decent quality of service (QoS).Data managers are used to measuring on/off environments. This isn’t much use for VoIP, which requires continuous performance management in real-time. A one-second delay is unnoticeable when downloading a file, but makes a conversation unintelligible. So how can organizations secure QoS? What’s the best way to train people who are strong on data, but not on voice transmission? How do enterprises “know” when voice quality is poor? And how good is “good enough”? The following check list should get you started:1. Assess Your Needs“Always start with the assessment,” says Ed Kovarski, principle consultant, Group Kae. “How many calls a day? What bandwidth do you have? Is it sufficient to handle the call volume you want to obtain?” From this assessment you can then determine bandwidth requirements. Then look at the routers and switches to see if they can deliver QoS. As a rule of thumb, always dedicate 50 per cent of bandwidth to VoIP. “We warn, ‘you might hear muffled voice over the IP line’” says Kovarski. “But you shouldn’t have to – nobody should know where you’re calling from. If you think about it, a regular POTS line isn’t superb – yet people are accustomed to it. The worst problem you encounter is ‘talking inside a barrel’.” Talk to every user to determine the sweet spot in terms of QoS requirements. If you ask the sales team they’ll tell you what they need and how bad it sounds. But keep in mind that not everybody will say what they do, or how they’re affected. And because VoIP is perceived to be ‘computer based’, many users won’t even bother reporting it – they’ll keep hoping it’s better next time.“But as soon as you pick up the phone it changes,” Kovarski adds. “Jitter, latency, how many packets you lose – it can become unbearable. It takes time because everybody’s perception of what is good enough is different. You’ll talk to the admin assistant, she won’t care. Her boss says she doesn’t want to sound like she’s in a tin can or concert hall. That’s when you’re getting into the grey area of QoS.”The presales phase is critical to early setting of customer expectations. That’s where system engineering and sales work together to clearly define expectations and put them in writing. “It is our responsibility to tell a customer how it will work in reality,” says Don Taylor, director, engineering and implementation, Unity Telecom .“When they’re using unmanaged networks, they need to understand the same type of performance characteristics they’ll experience on an Internet connection is what they’ll experience on a voice call. When they use home networks, there’s no way to guarantee that type of service today.” Customers must understand that once traffic enters the Internet it’s beyond the reseller or vendor’s control. It’s not a technology issue, it’s a deployment issue. You can install a VPN router and ensure QoS, but as soon as it leaves the router it’s anybody’s guess. “We have T3 connections that give us QoS,” says Barry Philips, group vice president and general manager of the advanced solutions group at Citrix Systems. “If somebody starts a video my phone call takes priority. If a company has done it correctly, they’ve set up similar pieces. Only when you run things over the Internet do you see these issues. Normally softphones cause them. Even if you have a 6MB connection cable modem at home, in the middle of the Internet is where it goes down and causes problems.” 2. Monitor Your VoIP NetworkThere are lots of tools to help IT workers measure jitter, delay, and specific aspects of VoIP. Monitoring tools automatically signal out when issues arise. Whether IT folks use them pro- or re-actively depends on what tools they have in place and what’s going on in that IT department. “The issue with monitoring software is that it’s either statistics, or one or zero,” Kovarski says. “Software can tell you where and when you’re losing packets. But it doesn’t tell how it impacts the individual. The best feedback is from users. And that’s the hardest thing to get, the constant feedback.” Some higher end phones have interfaces built in, providing feedback on the phone itself. But in Kovarski’s experience users only talk around the water cooler. They don’t interact with the phone – they use it and hang up. “If there’s some issue with the call, people start to generalize on IP phones that it’s the company network, which I don’t think is the case,” Phillips says. With legacy phones, you simply plug them in and they work, and though VoIP phones have the same form factor, it’s a completely different medium. Normally when VoIP is first implemented, everything works well, but customers can make changes any time: they may decide to add a few more phones, which requires adjustments, and changes the formulas.“A lot of time we come in after the fact. They’ve plugged into the network and started dialing numbers,” says Kovarski. “We don’t get called when they add the phones – we get called when the quality has been compromised to when it’s unbearable. Especially when they ramp up very quickly. It’s constant.” Or a customer can put a data server on the voice network and cause all kinds of havoc. “That’s the challenge with VoIP – a network that other people have access to,” says Taylor. “They can cause lot of grief. Training and documentation let those folks be aware of the potential issues.” 3. Train Users Diagrams of the network and IP addressing scheme let the IT staff know what sits where and what to avoid. “Survivability is key,” says Phillips. “Many times you’ll have a branch office running off a main PBX. For some reason the data connection is cut off. The telephone system has to be able to take and make calls independent of the main system. You want to leverage all the features and functionality of the main system, yet run it independently if something happens.” Citrix learned that customers didn’t want every user on IP; they merely wanted every user to have the features of IP. So it took a cue from what Microsoft Corp and Lotus (IBM) are doing with embedded voice capability in Outlook and Notes.“That’s why we developed Easy Call – to give voice capability over any phone, whether home or office,” Phillips says. “I hop over to my email client, type in a name, right click, and choose to voice call, IM, or send email – all from within Word or whatever. Being application agnostic, it’s much easier than teaching users to learn other apps. It can be run over a legacy telephone, and in any place. Easy Call will do for the other hundred thousand applications out there what Microsoft and Lotus are doing for Outlook and Notes.” 4. Secure Your VoIP NetworkIf you can secure your data network, you should be able to secure your voice network, because voice is now data. Ensure that VoIP traffic flows through the proper security devices and network paths. Each protocol has different threats and levels of maturity. Look to best practices of the manufacturers. “If you look at H.323 there are up to 11 ports that can be open in the firewall for that session,” Taylor says. “There have to be other things in place to secure it. Avaya Inc. has encryption from the desktop right through the network, including the controlling. It should be as secure as someone doing Internet banking or a remote connection with a laptop. The level of security on Avaya is good enough for the US military. I feel very comfortable using my cell phone without any worry about security.” 5. Train Your IT StaffFrom a technician perspective there are numerous VoIP training and certification options. Some are industry-specific and some vendor-specific. During the ongoing evaluation of a customer network, resellers sometimes look to the manufacturer. “You must have certified people – we have MCSEs, Avaya’s ACE, and Cisco CCIEs,” says Taylor. “We understand what’s needed to make a solid, robust network. We sometimes get different people to deploy it. We’re also affiliated with Live Office Communicator, and we have a Microsoft Gold Partner who comes in with us. We pre-test, bench test, and build pre-configurations to show the customer. That way we can get things down to an accurate cost.”But after the vendor and reseller leave, it’s up to IT staff to maintain the new voice network. Just what IT needs… more systems to run. “You’ll never see dedicated VoIP staff – it gets handed to the IT guys,” Kovarski says. “And people are overworked; so they don’t have the time to train themselves. The GUI on the screen gives them a speed gauge, but how does it translate to voice quality? We find people don’t tune it, and it has to be maintained. It’s like a car — invest time to maintain and tune it so it runs at optimum speeds.”

Determining VoIP Quality of Service

News | 06/10/2008 4:34 pm EDT

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