3 - Networking

We need to distribute a system, networking is the solution.

1. Fault Tolerance

Anything can fail
A system must keep working
And we must consider that
- Messages will be lost
- … 2. Distribution
Less likely that the entire system fails
How do we make the distribution “additive”?
- Sparseness, aka we do not want to rely on one part of the system.
2.a. Physical distribution
- The same/similar program running twice on the same machine
- We need to send copies of local data to achieve this 3. Persistence
We need a concept of time to decide mismatch between data
Messages can come in any order (due to restarting nodes etc)
- Therefore we can receive replies to messages we have not sent yet. 4. Bug repellence
Handle any messages in any order
…

Networks from scratch

How to connect any two programs or any two machines efficiently

Physical Layer
- Ethernet, CAN, USB, Bluetooth etc
Link Layer
- Differentiate between several physical connections
- MAC addresses (globally unique)
Network Layer
- Create a routing algorithm if we have a hierarchical system
  - Naive solution
  - In reality we have a local address, which tries to go to a remote address via a defau
Transport Layer
- UDP (User Datagram Protocol)
- TCP (Transmission Control Protocol)