How to model protocol packet structure?

[AndreasB]

Hello!

I'm quite new with UML and EA.
For a project I have to model a communication protocol or at least the structure of the protocol packets.

Inside a packet there are data fields like source address, destination address, packet control etc.
I use class diagram to model this in UML. The packet data fields are attributes of the class.

Now my problem:
While the packet header always has the same structure and length, the structure and length of the following data payload varies with a given data field of the header, the packet control byte. How would you model this?

By the way, can you suggest good UML 2.x books (german or english)?
I feel like I need some real life UML model examples to learn more than just the basics, notations and diagrams...

[fwoolz]

You could model it as a simple C struct using bitfields as required. Variable-length fields would be pointers (e.g. char*).