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Optimizing Performance
Estimating Message Traverse and Response Times
Message Traverse Time
Message Traverse Time is defined as the time required for a message to travel from
its point of origin to its intended destination over a network path. As the messages
travels over the network path, it may pass through—and be forwarded by—a
number of intermediate network devices, including switches and routers.
Message Traverse Time is impacted by several factors, including, for example, the
following:
z the number of forwarding network devices
z the transmission delay of each forwarding device
z network load
z message priority
Message Traverse Time can be estimated by determining the transmission delay
(the store and forward delay) of intermediate network devices and counting the
number of such devices. Assuming all forwarding devices are switches, and each
switch presents the same transmission delay, the following formula can be used:
Message Traverse Time =
(Switch Transmission Delay) x (Number of Switches)
Schneider Electric recommends that you estimate a worst-case Message Traverse
Time, as follows:
EIO0000000051 6/2010
Step
Description
1
Determine the worst case network load.
2
Obtain switch performance information, under varying network loads, and use
the worst case—i.e., the largest—transmission delay value.
3
Determine the logical network topology that yields the longest path—i.e. the
greatest number of switches—through which a message must pass.
4
Using the largest transmission delay value and the largest number of
forwarding switches, use the formula (above) to calculate a worst-cast
Message Traverse Time.
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