The Network Layer and Internet Protocol network provides best effort service
- Packets can be lost, duplicated, delayed, or re-ordered
The Transport Layer isolates applications from the network, allowing for:
- Demultiplexes traffic for different applications, letting multiple applications communicate
- Enhanced network quality of service to offer appropriate reliability
- Congestion control, which adapts to network capacity
TCP and UDP
There are only two types of transport protocols that are deployable on the internet due to Protocol Ossification:
- TCP (TCP-IP) - transmission control protocol
- UDP - user datagram protocol