Application Visibility

The primary goal of Application Visibility is to understand application usage and performance over the entire network.

To reach that goal, applications are classified in Application Groups (AGs), and each AG has specific QoS performance objectives (nominal bandwidth per session and two thresholds, maximum for one-way-delay, jitter, packet loss, RTT, SRT and TCP retransmission ratio), thus allowing to check whether performance objectives are met or not, and to calculate an Experience Quality Score (EQS) accordingly.

Application Visibility is:

• comprehensive (see the list of metrics below),
• highly accurate, relying on time synchronization from the network,
• very precise and non-intrusive: measurements are made on the actual data packets and not on test packets nor simulated flows,
• exhaustive: all IP packets are measured,
• independent from the operator network access and core technology (measurements are made at the IP layer level),
• confidential: the contents of user packets are not, at any time, stored, saved or even transmitted between the different system components.

Application Visibility provides the following metrics:

• the number of packets and bytes transmitted and received,
• the number of sessions,
• the following one-way metrics:
• Delay,
• Jitter,
• Packet Loss,

all three (called D/J/L) in both:

• ingress (from the LAN to the WAN) and
• egress (from the WAN to the LAN),

both:

• between the LAN interfaces of the appliances (LAN-to-LAN metrics, simply called LAN) and
• between their WAN interfaces (WAN-to-WAN metrics, simply called WAN):
• the following TCP metrics:
• RTT (Round Trip Time),
• SRT (Server Response Time),
• TCP retransmission ratio,
• the following composite metrics:
• Voice MOS (Mean Opinion Score),
• all flow EQS (Experience Quality Score).

 

Individual measurements are aggregated and analyzed according to multiple criteria (source and destination sites, source and destination subnets, Application Groups, applications, etc.). The results are presented in the form of detailed flows lists, real-time graphs, charts, etc., and archived with periodic aggregations. They are made available for subsequent processing or reference, and can be used to generate alarms, analyze long-term trends, forecast future traffic increase to estimate optimum network sizing, etc.

Users can specify their own aggregation criteria, thus taking into account their enterprise organization (e.g. the different countries, departments, services, etc.).

Time Synchronization

Appliance synchronization for the Client is used for correlation, hence for Delay/Jitter/Loss measurement.

Monitoring

The Monitoring dashboard function provides a real-time view of the performance and activity of the observed traffic through graphs.