Compression for communication with proxies must be implemented:

• Server and Proxies will be built with enabled compression by default, therefore all communications between Server and all Proxies will be unconditionally compressed starting from version 4.0.0.
• We must support build of Server and Proxies binaries without compression. In this case no compression will be used between Server and all Proxies.
• There will be no buffer size threshold to define if compression should be used or not. If compression is enabled, it will always be used.
• Low level version of the communication protocol must clearly indicate use of compression.
• Zabbix processes must produce clear warning messages in case if there is protocol mismatch, i.e. compression is not supported or version of the protocol is not supported. It must also work for future versions of the protocol.