The Link Layer - Services
Learn about the responsibility of the link layer and the services provided by it.
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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 ...