A Solution

• Experience in protocol design tells us that forming multiple layers, each one with defined “interface” to its lower any upper layers as well as a defined functionality helps to keep things

  • simple
  • extensible & powerful (new functionality “immediately” available to older parts)
  • “change-ignorant” (new functionality does not break existing code)

• Many successful protocols use this approach (e.g. IP stack itself, SMTP/MIME)