Experts in a recent panel session at VON 2005 addressed the challenge of troubleshooting VoIP. The panel included representatives from Avaya, Cisco Systems, Empirix, RADCOM and Dr. Clark from Telchemy. They offered various views on the state-of-the-art but, as some members of the audience noted, the overall picture was incomplete. People were there to hear something specific about how to solve their problems -- useful insights were offered but they weren't hearing solutions. It was clear that the ability to analyze perceived performance degradation and resolve specific problems was severely lacking.
Interestingly, this perceived lack was present regardless of consideration for pre- or post-deployment stages of VoIP implementation. An effective diagnostic capability is needed at all stages of the life cycle, from beginning to end. The full path to success had been described but was apparently not yet available.
A rough summary of the vendors' views identifies three critical steps to successfully manage VoIP:
- Test and/or monitor network paths for VoIP performance
- Analyze VoIP performance to identify presence of degradation
- Identify, localize and resolve sources of degradation
The good news
- Passively monitor packets, at high speeds and with great control
- Generate precisely controlled synthetic application traffic between two points
- Instrument routers, exchange points, hosts, servers and IP phones with probes
- Gather and archive statistics from network devices
And analysis has finally matured to the point where IP performance can be summarized succinctly (usually as MOS or Mean Opinion Score). Most people who work with VoIP know that MOS around 2.7 is not satisfactory and that 4.1 is excellent. The analytic means are now as plentiful as the monitoring and testing techniques:
- Characterize overall IP network performance in terms of packet behaviors (e.g. E-model)
- Compare reference files to those transferred (e.g. PESQ, PAMS)
- Correlate fault statistics from numerous devices (e.g. RTCP-XR)
- Perform application- and media-specific call analysis (e.g. H.323 and SIP)
- And numerous proprietary algorithms specific to data gathering methodology
So the industry is almost ready to make VoIP work and keep it working. Except…… step three is still an unanswered question -- supposing that you know that you have a problem, how do you find its source and fix it?
And not a trivial oversight -- this is a very hard nut to crack. So it's not a wonder that vendors don't have means of fixing detected issues. In fact, most VoIP vendors have little-to-nothing to offer their customers struggling with problems. Some, as claimed by Avaya, are working hard to develop tools. Even the so-called network performance and management vendors come up short in solving the diagnostics problem.
But smart people are working on clever answers. And maybe 2005 isn't the year for the full solution. But the industry clearly knows what it needs -- a far cry from the last few years when the dull roar of deployments going SPLAT! was only met with the sound of heads being scratched.
Now we just have to wait. It won't be long now…
Chief Scientist for Apparent Networks, Loki Jorgenson, PhD, has been active in computation, physics and mathematics, scientific visualization, and simulation for over 18 years. Trained in computational physics at Queen's and McGill universities, he has published in areas as diverse as philosophy, graphics, educational technologies, statistical mechanics, logic and number theory. Also, he acts as Adjunct Professor of Mathematics at Simon Fraser University where he co-founded the Center for Experimental and Constructive Mathematics (CECM). He has headed research in numerous academic projects from high-performance computing to digital publishing, working closely with private sector partners and government. At Apparent Networks Inc., Jorgenson leads network research in high performance, wireless, VoIP and other application performance, typically through practical collaboration with academic organizations and other thought leaders such as BCnet, Texas A&M, CANARIE, and Internet2. www.apparentnetworks.com
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This was first published in October 2005