# Routes and Flow Control

For global topics where messages are routed between servers, flow control can be specified for a topic on either the server where messages are produced or the server where messages are received. Flow control is not relevant for queue messages that are routed to another server.

If the `flowControl` property is set on the topic on the server receiving the messages, when the pending message size limit is reached, messages are not forwarded by way of the route until the topic subscriber receives enough messages to lower the pending message size below the specified limit.

If the `flowControl` property is set on the topic on the server sending the messages, the server may block any topic `publishers` when sending new messages if messages cannot be sent quickly enough by way of the route. This could be due to network latency between the routed servers or it could be because flow control on the other server is preventing new messages from being sent.

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