Specifications

Optimizing Performance
EIO0000000051 6/2010 101
Allocating Network Bandwidth
Introduction
Maximum network bandwidth equals your network speed, for example 100 Mbps.
When designing your control network, you must allocate network bandwidth among
the control application messages required by your application.
NOTE: Schneider Electric recommends you reserve at least the following amounts
for processing explicit messaging:
z 10% of network bandwidth
z 10% of CPU processing capacity for each network device
Message Load and Message Bandwidth
Message Load—in packets per second (PPS)—represents the number of packets
in a single message that are received and sent within one second. Message Load
can be estimated as follows:
Message Load =
(number of packets per connection) x (number of connections) / RPI
The number of packets per connection value depends on the capacity of the device,
and can be either:
z 1: for connections that support uni-directional communication
z 2: for connections that support input and output (for producer/consumer mode) or
request and response (for client/server mode) per one time bi-directional
exchange, or
The connection can be used for either explicit or implicit messaging. For UDP-based
explicit messaging, assume that each client represents one connection, and that all
messages are transmitted cyclically.
Message Bandwidth (in bits) can be calculated as follows:
Message Bandwidth = message packet size (bits) x Message Load
Based on the portion of network bandwidth you want to allocate to a particular
message, you can use the Message Load and Message Bandwidth formulae to
calculate the fastest RPI for the message.