Protocol Version Handshake #11
Description
from pg 143 Designing Distributed Control Systems by Eloranta, Koskinen, Leppanen, Reijonen
Nodes should use the latest version of a communication protocol, as it is probably the most efficient. However, a system may also have nodes that use older protocol versions, and there must be a way to communicate with them. The most efficient protocol common to all nodes should be determined.
Therefore
Design a handshake sequence common to all protocol versions. In the handshake, all nodes announce the highest protocol version they support during system start-up. Once nodes have announced their highest version, each node selects the highest common version for communication.