The VoIP challenge
is an excellent way for companies to combine cutting-edge technology and cost
efficiency. At the same time, it presents new challenges that need to be metreliability,
resiliency, usability, and security, says Mika Rautila.
The growing trend today is to have voice and data travel through the same network.
The potential cost benefit of this convergence is significant and hence the
shift to using Voice over IP (VoIP), which in simple terms means making phone
calls over the Internet, will be inevitable. The expectations from this new
technology are high.
When you pick up your landline phone to make a call, you expect to hear the
ringtone within moments. You also expect to be able to talk to the person at
the other end without breaks in conversation or delayed voice. We are used to
the reliable phone service over traditional lines, with good sound quality,
and we take reliability and fault-tolerant phone lines for granted. The telecom
industry calls this 99.999 percent availability, which represents the level
of service people are expecting. These expectations could be unrealistic when
voice is carried over the Internet.
Issues to be overcome
We are all familiar with Internet congestion when we surf on the data highway,
but we do not expect that with our phone calls. The way congestion can impact
a phone conversation is to introduce latency and jitter. If there is a delay
in speech of over 150 ms, a latency of a fraction of a second, the human ear
can sense it. On the other hand, jitter results in bad voice quality, as the
voice arrives at varying intervals due to the nature of the data networks. Further,
data lines are usually not designed to be as fault tolerant as traditional landlines,
and therefore service breaks for phone calls over the Internet can be frequent
The challenges may become apparent only after the implementation of the new
technology. These challenges are often related to the previously mentioned congestion
of the data networks within and outside the company, reliability of Internet
connections, and security of these connections. Since these issues require different
technologies than what has been used for the actual VoIP implementation, they
may not be addressed at all.
The traditional way
The traditional way to handle congestion in the data networks would be to use
bandwidth management. What bandwidth management means is that we can determine
how much of our capacity can be used for each type of traffic. For instance,
we could stipulate that e-mail be designated 50 percent of the line capacity,
while Internet browsing could be given 30 percent, VoIP 10 percent, and the
rest of the traffic 10 percent. This way you can ensure that each type of traffic
gets only its allotted amount and does not take up the whole capacity thereby
depriving other traffic their bandwidth.
An alternative solution
An alternative, in some cases it could be more efficient, would be to separate
certain traffic onto a private road through the Internet. The earliest implementations
of this needed to use dedicated lines from service providers, but today, with
modern technology this type of a private road through the Internet can be implemented
with little initial investment and no hassle using say DSL lines.
Traditional leased lines cost around 400 pounds per month, whereas with the
use of modern technology the cost comes to around 100 pounds per month since
you can use regular Internet connections. To reach the reliability of leased
lines you would naturally need at least two regular lines so the total cost
would be around 200 pounds per month.
Benefits of the Alternative
With voice this type of road privatisation has some interesting benefits. In
the traditional implementation of VoIP where all traffic shares the same road,
other traffic may have an impact on the voice quality. Not only that but other
traffic can impact the line reliability. When there is an accident on the road,
other lanes may have to be closed as well. Similarly in the data network, congested
Web traffic can impact voice traffic.
Reliability of private lines could be enhanced by using multiple roads (i.e.
multiple Internet links) that lead to the same destination. With modern technology
this is possible. By having more roads you ensure that when you pick up the
phone the Internet is not down. We may be used to not being able
to surf the Internet or send e-mail at all times due to service breaks, but
phone calls are more critical and the expectation is that you are always able
to make a phone call.
Security of voice on the Internet
Since voice now uses the same path as other data traffic, it faces the same
challenges and threats that are more commonly linked with the Internet. Viruses,
worms, trojan horses, Denial-of-Service (DoS) attacks, and connection hijacking
are all possible threats for voice. Voice traffic can be attacked, hacked, intercepted,
re-routed, and degraded just as any data packet on the data network.
Also, security needs special attention when other traffic is present. In order
to avoid most security problems, e.g., malicious eavesdropping conversations,
the voice traffic should be at least encrypted. Additionally with a private
road for voice, security is increased by the mere fact that you do not have
to advertise or let other people know about this road. This also reduces the
possibility of someone being able to run a successful DoS attack. So Distributed
DoS protection is in fact built into this type of scenario, whereas in the traditional
implementation a DoS attack against a companys Web server can also cause
the voice traffic to halt.
Companies have implemented or are planning to implement VoIP solutions where
voice, data, and video can travel over the Internet. Today this is already an
excellent way for companies to combine cutting-edge technology and cost efficiency.
At the same time, it presents new challenges that need to be metreliability,
resiliency, usability, and security.
The author is the Chief Technology Officer of Stonesoft