Effective Voice Traffic Analysis using NetFlow Analyzer

Voice traffic has spread its presence everywhere right from SMBs to large enterprises. Communication happens through VoIP at different levels right from customer support to teleconferencing to internal communication etc. VoIP has a major role in ensuring business continuity & it thus becomes a critical application that requires constant monitoring & control.

NetFlow Analyzer makes monitoring VoIP traffic and analyzing VoIP Link capability very easy.

There are two things that we need to analyze while monitoring VoIP traffic on a network:

  • Performance of Link (Traditional IP SLA technology).
  • Monitoring QoS Policies for VoIP.

Performance of Link (Cisco IP SLA):-

If the network has Cisco router with IOS (12.4 or above) at their Head Office and branches, then monitoring the link performance between the sites which carry VoIP traffic would be much easier with Cisco IP SLA monitoring in NetFlow Analyzer.

To know how to configure Cisco IP SLA VoIP in NetFlow Analyzer, you can refer this link and to know more about reports generated by
Cisco IP SLA VoIP monitoring, click here.

Now getting in to a typical scenario where a Network Administrator creates a VoIP Monitor in NetFlow Analyzer and is informed through the NetFlow
Analyzer reports that there are factors like packet loss, jitter and very high latency and the MOS score is very low, this not a good sign. He thinks what is the next step to resolve this.

QoS Implementation:

Then network admin implements QoS policy on his link that carries Voice traffic as below

class-map match-any VOIP-SIGNAL

match ip dscp cs5

match ip precedence 4

match ip precedence 3

class-map match-any VOIP-RTP

match ip dscp ef

match ip precedence 5



policy-map QOS-Policy


priority percent 5

class VOIP-RTP

priority percent 70

class class-default




interface Serial0/0/0

service-policy output QOS-Policy

After implementing QoS policies on the links, he now wants to check whether the applied policies are performing as they intended to do. This can be done using following features in NetFlow Analyzer:

  • IP groups
  • CBQoS monitoring

IP Groups:-

An IP group is created with ‘Between Sites’ option placing
the IP network of the IP phones in one Site
under ‘FROM’ and the IP network of IP phones in the other site under the
‘TO’ category for which QoS policies are implemented.

With IP group traffic report, he finds that now the VoIP
traffic is been getting prioritized and utilizing the maximum bandwidth.

CBQoS (Class Based QoS Service Monitoring):

With CBQoS reporting functionality, QoS policies that were
deployed to mark voice traffic can be verified. The CBQoS report in NetFlow
Analyzer will show the pre and post-policy traffic usage along with any drop in
each traffic class.

After implementing the QoS policies and once it has been verified, the network administrator sees that Packet loss, Latency and jitter considerably reduced and the users are reporting good call quality.

Thus, NetFlow Analyzer helps transform your VoIP environment into an effective & high-quality VoIP environment.

Praveen Kumar
NetFlow Analyzer Technical Team

You Can Learn More About the ManageEngine Product Line By Going to manageengine.optrics.com

The original article/video can be found at Effective Voice Traffic Analysis using NetFlow Analyzer

Leave a Reply

Your email address will not be published. Required fields are marked *