B. The transport layer divides a data stream into segments and adds reliability and flow
C. Packets are created when the network layer adds Layer 3 addresses and control
information to a segment.
D. The data link layer adds physical source and destination addresses and an FCS to the
E. Packets are created when the network layer encapsulates a frame with source and
destination host addresses and protocol-related control information.
Answer: B, C
The Transport Layer:
You can think of the transport layer of the OSI model as a boundary between the upper
and lower protocols. The transport layer provides a data transport service that shields the
upper layers from transport implementation issues such as the reliability of a connection.
The transport layer provides mechanisms for:
- Segmenting upper layer applications
- The establishment, maintenance, and orderly termination of virtual circuits
- Information flow control and reliability via TCP
- Transport fault detection and recovery.
Layer three of the OSI model is the network layer.
- The network layer creates and sends packs from source network to destination network.
- It provides consistent end-to-end packet delivery services and control information.
- It creates and uses layer3 addresses for use in path determination and to forward packets.