MQTT and Point-to-Point?

[emiltin]

MQTT is based on a broker architecture with all communication passing through a central broker. This has several benefits.

But in some existing scenarios, sites communicate directly with each other. How would we handle these scenarios? Is a problem for messages to go through the broker, or is in fact an easy to way to handle site-to-site communication?
Are there timing requirements or other, that require direct communication?