possibility to transmit frames from multiple lines in one packet
It would be nice to have the capability of transmitting frames of multiple E1 lines within a single packet. In more complex setups this helps to reduce the overhead, as the packet headers are only present once.
The challenge is to achieve this without introducing more overheasd in the single-line case.
Simple concatenation is not possible, as we use the length of the packet as an implicit indicator on the number of frames contained.