The Link Layer - Services
Explore the link layer's role in networking within distributed systems. Understand services like framing, medium access control protocols, reliable delivery, and error detection techniques that ensure data moves correctly between nodes.
While the physical layer is responsible for the transmission of good signal through a physical medium, the link layer is responsible for the movement of a packet of information from one node to a neighboring node. In this context, we will consider a node to be a neighbouring node if it is connected through a single communication link, regardless of whether it’s wired or wireless.
Services provided by the link layer
The link layer can provide the following services:
Framing
This process involves the encapsulation of payloads from the higher layers of the stack into the link layer packet, commonly referred to as a frame.
Link access
A physical link may be shared between multiple nodes, which means that there must be a way to mediate access to this link, so that the nodes can coordinate with each other to ensure only one of them transmits data at a given time. This is achieved through protocols known as medium access control (MAC) protocols. These protocols can be grouped into three main categories:
- Channel partitioning protocols
- Random access protocols
- Taking-turn protocols
Channel partitioning protocols
Channel partitioning protocols partition the channel into parts that can be used concurrently by more than one node. There are three main ...