System Design Ideas (contd)
Layering and encapsulation:
- Allows a subroutine abstraction between a layer and its adjacent layers.
- Layering allows pipelined implementations.
- Application layer framing: packet format at every layer flexible and application-defined
Circuit-switching: resource (circuit) reservation followed by time-bound transmission.
- Resources wasted if unused: expensive.
- Straightforward to assure quality for voice (150 ms round trip delay, 64 Kbps bandwidth).