Layering sequences in UVM !!!

We come across different types of layering requirement for different  protocols. Basic ones are as follows.

1. One to one mapping  --  One higher level protocol frame is mapped to the payload of one lower level protocol frame.
2. One to many mapping -- One higher level protocol frame is mapped to the payload of many lower level protocol frames.
3. Many to one mapping  -- Many higher  level protocol frames are mapped to the payload of single lower level protocol frame.
4. Many to many mapping  -- Many higher level protocol frames are mapped to the payload of many lower level protocol frames. 

What ever be the layering scenario , the basic principle to generate a layering transaction is to randomize the higher level sequence and use byte_pack to convert it to a byte stream and package the bytes in the lower level sequence.