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Call Trace Probes Decline in Value, Cost More and Don’t Work for Data

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          Call Trace Probes
Decline in Value, Cost More
  and Don’t Work for Data
                           White Paper
                   by Velocent Systems




                              In association with
    Call Tr aCe ProbeS DeCline in Value, CoST More anD Don’T Work for DaTa




                                            Call Trace Probes Decline in Value,
                                            Cost More and Don’t Work for Data



                                                      When it comes to measuring the performance aspects of today’s wireless
                                                      infrastructures, quantifying the level of network quality is probably the most
                                                      important task. However, while mobile operators agree that network quality
                                                      — or the lack thereof — is the primary reason for subscriber churn, there is
                                                      little agreement across the industry on how to truly measure end-to-end
                                                      session quality and thereby effectively manage the mobile broadband network.

                                                      for years, mobile operators have determined voice-quality problems on their
                                                      networks by using call trace probes to monitor signaling messages or the
2
                                                      control plane and obtain the associated key performance indicators (kPis).
                                                      because the bandwidth is fixed, the basic monitoring premise has been that
                                                      if the voice call is set up properly and doesn’t drop, the quality must be good.

                                                      Yet because data traversing the mobile broadband network is obviously
                                                      different from voice, the traditional voice-centric monitoring approach and
                                                      the resulting kPis no longer are effective. Call trace kPis that only monitor
                                                      session set-up and tear-down signaling messages lack the monitoring
                                                      capabilities necessary to ensure data-network quality. They do not monitor
                                                      the user plane — that vast portion 98 percent of the traffic — where the
                                                      user’s actual content is transported.




       Table of Contents
       2    Introduction
       3    Voice-Monitoring Tools
            Don’t See Data Traffic
       4    Call Trace Probes Decline in
                                                                                                                               P2P
            Value, Cost More and Don’t
            Work for Data                                                                                             Stream           HTTP

       4    Layer-7 Probes Do Not Offer                  Visibility “inside the                                                Email
            the Necessary Visibility                     pipe” is necessary
       5    Benefits of Handset-to-Server                to improve customer
            Visibility                                   experience
       5    Positioning Mobile Operators
            for Long-term Success




    VeloCenT.CoM
                                                                              Call Tr aCe ProbeS DeCline in Value, CoST More anD Don’T Work for DaTa




                                                                                                     CAPTURE POINT           App. Server
Consequently, leading mobile operators around the world
want a solution specifically designed to provide the essential                                  Mobile
                                                                                                                  Internet
                                                                                               Network
kPis for monitoring and measuring the quality of their rapidly
evolving broadband networks. These kPis include:
                                                                                      End-To-End Network Visibility
 network congestion events, retransmission, packet loss
 per-session peak throughput down to subsecond                       End-to-end measurements provide visibility as perceived
                                                                      by the customer
  granularity
 mobile network latency, using existing packets as “pings”
  that provide active probing benefits — without artificially        Voice-Monitoring Tools Don’t See Data Traffic                                     3
  injecting traffic — to measure the quality of every packet         Call trace probes emerged in 1997 to automatically decode
  traversing the broadband network                                   the signaling messages of voice calls moving across mobile
 active session drops, using end-to-end user-plane                  networks. at that time, these state-of-the-art monitoring and
  transport (TCP/iP), rather than network layer between              measuring techniques focused on isolating the specific path
  network elements (i.e., Gn, iuPS, iub), to detect drops            of a problem voice call and then using a portable call trace
  during active transfer of data that affect the user                probe to determine if signaling was the problem. in addition to
  experience                                                         increasing the productivity of network engineers, who had been
 cell-site traffic classification, to determine if traffic is
                                                                     spending one-third or more of their time manually decoding
  “bursty,” which can be oversubscribed, or sustained                the signaling messages of dropped, and blocked voice calls,
  streaming, which should not be buffered excessively                call trace probes worked well for analyzing actual problems
                                                                     reported by customer care. However, to isolate and identify
in addition, these new end-to-end kPis provide a view from           hidden and even potential dropped and blocked-call problems,
the user’s perspective and are not limited to individual link        technicians have had to probe every link in the network. never-
views that only tell part of the story.                              theless, network operators have justified the significant cost and
                                                                     complexity of using the voice-probe system by arguing that
armed with such end-to-end, data-centric kPis, engineers can         resolving problems before they affected customers was the
not only quickly isolate problems that affect network quality and    fastest way to increase subscriber satisfaction and thus
set priorities for resolving them but also effectively analyze the   reduce churn.
root cause(s) of those problems. Compared with a call trace
probe, with its coarse nature and loss of metadata, data-centric     Yet Michael Treacy and frederik Wiersema, in their book
kPis offer a much broader range of root cause analyses.              Discipline of Market Leaders, warned that “Yesterday’s
                                                                     truisms become tomorrow’s falsehoods, and a company
                                                                     can easily develop blind spots that impair its people’s skill
                                                                     at sensing the potential of new technologies and concepts.”
                                                                     Given the growing emphasis on the user experience in
                                                                     today’s mobile broadband communications, their warning
                                                                     applies to the need for data-centric monitoring techniques
                                                                     that maximize the quality of that user experience.



                                                                                                                                      VeloCenT.CoM
    Call Tr aCe ProbeS DeCline in Value, CoST More anD Don’T Work for DaTa




            Call Trace Probes Decline in Value,                              Layer-7 Probes Do Not Offer the Necessary Visibility
            Cost More and Don’t Work for Data                                Some call trace vendors have augmented their probes with
            Today, network engineers still use call trace probes to          layer-7 internet-based probes, which can monitor services
            measure dropped calls and determine/analyze the root             such as multimedia messaging service (MMS) and Web
            causes of problems related to network provisioning. never-       browsing. Sometimes called “Gi probes,” these probes are
            theless, the value of these probes is declining rapidly          specifically designed to monitor internet servers and provide
            because of three factors:                                        visibility into internet services. They work well for enterprises,
             network operators have turned their focus to                   iSPs and even mobile operators’ “walled garden” servers
               monitoring data                                               that require iP call trace monitoring.
             the industry has solved many historical provisioning
               problems                                                      However, they provide little or no visibility into the mobile
                                                                             network because they do not fully monitor “inside the cloud,”
             mobile broadband data is the fastest growing segment
                                                                             that is, inside the mobile broadband network. because these
               of the wireless marketplace.
                                                                             Gi probes reside outside the broadband network, they
                                                                             cannot provide visibility into the critical information that lies
            With data service now the primary driver for most operators
                                                                             inside the network. as every network operator knows, the
            for mobile network profitability, network engineers have
                                                                             “hot spots” or congestion points in a mobile broadband
            expanded their use of call-trace probes to monitor broad-
                                                                             network occur within cells, cell sites, radio network control-
            band data services as well. This approach is even more
                                                                             lers (rnCs) and/or Serving GPrS Support nodes (SGSns).
4           expensive than monitoring the voice network, simply because
                                                                             Consequently, layer-7 internet probes cannot isolate mobile
            the number of links that must be monitored increases as
                                                                             network quality problems and thus have little value when it
            bandwidth increases.
                                                                             comes to monitoring and improving mobile network quality.

            even more important, using call trace probes to monitor
                                                                             Yet another example of how yesterday’s truisms can become
            mobile broadband network performance completely misses
                                                                             tomorrow’s blind spots is emerging as the industry transitions
            the mark. for example, instead of providing network-congestion
                                                                             to long-term evolution (lTe) technology. even with today’s
            kPis that analyze packets traversing the network, the call
                                                                             direct tunneling, the network is flattening very quickly,
            trace probes provide a count of irregular signaling messages
                                                                             eliminating most of the links currently monitored by call
            that were retransmitted. These kPis only isolate signaling-
                                                                             trace probes. because lTe technology will eliminate the
            message performance problems that are often times
                                                                             need for rnCs and SGSns, network operators who spend
            transported on links different from those that transport user
                                                                             money to monitor the links between these network elements
            content. They do not focus on identifying congestion that
                                                                             and the cell sites they aggregate, for all intents and purposes,
            causes packets to be lost from the user content —
                                                                             are throwing money down a black hole. Given that the
            packet loss that actually affects the user’s experience.
                                                                             communications network of the future clearly will be a mobile
                                                                             broadband network with flattened signaling paths, the need
            another example of call trace kPis’ ineffectiveness in
                                                                             for and value of call-trace probes will diminish even more.
            monitoring broadband networks occurs in latency issues.
            The call trace probe simply monitors the time it takes for
                                                                             A Monitoring Solution Built for Mobile Broadband
            a signaling message to reach the next signaling point and
                                                                             To tackle both today’s and tomorrow’s broadband-monitoring
            return a message. as mentioned earlier, because these
                                                                             challenges, leading mobile operators are turning to data-
            signaling messages often times traverse different links,
                                                                             centric solutions that focus on the part of the oSi stack that
            the measurement only reflects signaling-message latency,
                                                                             network and internet call trace probes ignore: layers 3 and
            not user plane transport latency.
                                                                             4 where the transmission control protocol (TCP) and user
                                                                             datagram protocol (uDP) packets flow. using combination
                                                                             of hardware-based packet processing and purpose-built
                                                                             software engines, solutions such as the oneVu system from




    VeloCenT.CoM
                                                                                 Call Tr aCe ProbeS DeCline in Value, CoST More anD Don’T Work for DaTa




      APPLICATION                  APPLICATION              LAYERS 5-7
                                                                         Benefits of Handset-to-Server Visibility
                                                                         by correlating terabytes of metrics, data-centric solutions
                                                                         provide the data required to summarize more than 130 kPis;
                                                                         they then aggregate these kPis in real time into key quality
                                                                         indicators (kQis) according to cell (sector), cell site, the type
                                                                         of device in use, rnC, SGSn, GGSn network elements (nes),
           TCP                         UDP                  LAYER 4
                                                                         access point name (aPn), servers and iP or uDP port service.
                                                                         Thanks to this broad range of kPis and kQis, which includes
                                                                         end-to-end measurements from handset to server, mobile
                                                                         operators achieve several specific benefits, including:
                           IP                               LAYER 3
                                                                          the ability to isolate and prioritize problems before they
                                                                           affect customers--and without throwing money everywhere
                                                                           in the hope that it will solve the problem(s)
                                                                          real-time end-to-end kPis on session quality, summarized
                                                                           into real-time kQis
                 NETWORK BEARER                             LAYER 2
                                                                          effective and efficient network-management and
                                                                           optimization capabilities
                                                                          optimized capacity planning, based on the information
Monitoring layers 3 and 4 of the OSI stack is critical to                                                                                                 5
monitoring the user plane for customer experience                          necessary to develop appropriate infrastructure and
                                                                           backhaul investment strategies

Velocent basically enable operators to identify and resolve              Positioning Mobile Operators for Long-term Success
hidden problems that degrade service quality, including                  Today’s combination of wireless market saturation, a growing
backhaul bottlenecks.                                                    number of consumer 3G applications, inexpensive 3G handsets
                                                                         and fierce pricing competition in the 3G data services market
Data-centric solutions offer a highly granular view of                   poses serious bandwidth problems for mobile broadband
network quality on a per-user, session-by-session basis,                 networks. unless mobile operators have the monitoring tools
for all service-delivery components. Solutions can look                  that can help them identify and resolve these problems quickly,
for packet abnormalities, aggregate them statistically                   the quality of subscribers’ experiences on the network will
and isolate the components that affect service quality.                  decline, and the rate of churn will rise.
by providing visibility at cell-site granularity, these solutions
enable mobile operators to set priorities for resolving                  With millions of dollars at stake, mobile operators recognize
problems that affect service quality. as a result, operators             that their ability to monitor and quantify the user experience
can reduce backhaul investments, which account for a large               is critical because it directly affects market share. Certainly
percentage of operating expenditures as well as improve                  the best way to improve customer satisfaction in any industry
network optimization and maximize return on investment                   is to deliver top-notch customer support. With data-centric
(roi). using summarized informational reports, operators                 monitoring solutions such as Velocent’s oneVu, now available,
also can target their capital expenditures (CaPeX) to                    mobile operators can measure each experience of each
address network problems and improve service quality.                    customer and take the necessary steps to maximize those
equally important in today’s ultracompetitive market, they               experiences. armed with performance-measuring systems
can optimize the quality experienced by each user on                     designed for the data world, mobile operators can effectively
the network.                                                             position themselves to succeed in the market, both in the
                                                                         near term and over the long haul.




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Description: When it comes to measuring the performance aspects of today’s wireless infrastructures, quantifying the level of network quality is probably the most important task. However, while mobile operators agree that network quality — or the lack thereof — is the primary reason for subscriber churn, there is little agreement across the industry on how to truly measure end-to-end session quality and thereby effectively manage the mobile broadband network.