Monitoring with Riverbed Steelhead › Concepts › Monitoring when Optimization Stops › Temporary Interruptions

Temporary Interruptions

If the monitor feed temporarily stops receiving Steelhead-optimized packets, the management console uses data from the unoptimized server SPAN to report on the application in the Server segment. Several criteria are used to determine whether an interruption is temporary or permanent, but a temporary interruption is typically less than 20 minutes.

While the management console temporarily reports the unoptimized application data from the mirrored switch port in the Server segment:

• All metrics on the Optimization page are accurate, although not all metrics populate.
• Measurements for the unoptimized sessions do not affect the Client or WAN segments.
• The Server segment is accurate because the management console uses the more accurate data from the mirrored switch port that is closest to the server.
• Network Round Trip Time [Server] on the Engineering page shows an increase because it no longer gets 100 percent local ACKs. The pass-through measurements show actual Network Round Trip Time out to the client.
• Retransmission Delay [Server] and Packet Loss Percentage [Server] can increase.

When optimization data resumes, the management console automatically reports the segmented application data in the Client, WAN, and Server segments.

Temporary interruptions to optimized monitoring occur, for example, when:

• Optimization stops. This type of interruption occurs when a Steelhead appliance does not have the resources to optimize more sessions.
• Monitoring stops. This type of interruption occurs when there is a disruption in the link between the Steelhead appliance and the monitoring device. If a monitoring device stops receiving packets on its Monitor NIC, monitoring stops.