Network Round Trip Time

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Network Round Trip Time

Network Round Trip Time is the amount of time it takes for a packet to travel round trip between the server and clients on a network, excluding latency from retransmissions.

Application and server processing times are excluded when calculating this value. The management console continuously refines the Network Round Trip Time by looking at the TCP acknowledgments for all application traffic, not just connection setup times, to build the most accurate model.

Use the Network Connection Time as a baseline for carrier latency and comparison to NRTT times.

Look for	Might Indicate
Increases in NRTT that correspond with increases in the number of observations	Insufficient bandwidth between the client hosts and the server for the volume of data being transmitted by the application. Increases in NRTT that do not correspond to increases in the number of observations might indicate this: Another application is consuming the available bandwidth between the remote client hosts and the application server. The carrier’s network switched to the protected or alternate path. Some error condition exists in the network.
Number of observations increases with an increase in NRTT	Root source of the delay increase. See the Data Volume and TCP sessions views to determine if there was a corresponding increase in data, TCP sessions, or both.
Number of observations decreases with the increase in NRTT	Other monitored applications between the monitoring device and the remote clients might be responsible for the apparent reduction in bandwidth.
When comparing subnets in the same office location, such as the same building, you should see a minimal difference in NRTT for the same application	A difference greater than 10 ms could be caused by one of the following: Problems in the LAN architecture Incorrectly configured switch or NIC port settings Error conditions in the network Utilization differences along the physical paths within the LAN
Users in remote offices at varying distances from the server and operating over different WAN links to the server experience different latency and NRTT	Provisioned bandwidths, link utilization patterns, and access technologies; for example, ATM versus IP VPN.