In TP, we create a listener on 224.0.0.75:7500 (hard-coded, fixed multicast address/port). When pinged, it returns information in key/value format, such as

• clusterName: DefaultPartition
• address: 192.168.5.1
• version: 2.2.9
• members: 192.168.5.1, 192.168.34.2, 192.168.0.2
• configuration: "UDP:FD:GMS"

The format is simple: keys and values are both strings, so we can have programmatic discovery of clusters.
If the returned information is > 1472 bytes (ethernet MTU - IP and UDP datagram size), then we simply break up the reply into multiple packets, each packet has to have the clusterName and address fields present though, to identify them.
This might be used in the future to not just query information, but also submit commands. To ensure future compatibility, make sure to design the format in an extensible way, e.g. keys and values are strings.