# Efficient and Secured Mechanisms for Data Link in IoT WSNs: A Literature Review
## 2 Layered Network Architecture  
A base station and a high number of sensor nodes are used in this network. Network nodes may be arranged in concentric circles. The structure consists of three cross layers and five interlocking layers. The five architectural layers are as follows:  
* Application layer;
* Transport layer;
* Network layer;
* Data link layer;
* Physical layer.  
The following are examples of the three cross layers:  
* Power management plane;
* Mobility management plane;
* Task management plane.  
To improve overall network efficiency, these cross layers are primarily utilized to govern the network and make the sensors act as one. An architectural diagram of WSN as well as WSN's five layers is shown below in Figure 3.  
However, the main focus of this research is the data link layer, so a comprehensive discussion of a data link is included below:  
1. **Data Link Layer** The data connection layer is a program's protocol layer that regulates data transit through and out of the physical link of a network. The Open Systems Interconnection (OSI) model is used for telecommunication protocols [14]. Data bits are decoded, organized, and encoded at the data link layer until they are transferred as frames between two nearby nodes on the same LAN or WAN [15]. The data connection layer also manages the recovery of devices from collisions that occur when many nodes attempt to send frames simultaneously. The data link layer has two sub-layers: the logical connectivity control (LLC) sub-layer and the network access control (MAC) sub-layer [16]. The communication channel that links the adjacent nodes is known as the tie, and each datagram must be sent via a separate connection from the source to the destination [17].  
The main role of the data connection layer is to transport datagrams across a single link. The data link layer protocol defines the packet structure and behavior for packets ex  
Figure 3: Architectural diagram of WSN (Reprinted from ref. [13]).  
changed across nodes, including error detection, retransmission, flow control, and random access [18; 19]. It allows nodes to use a traditional medium and make effective use of it to control data flow. It also handles transmission troubles. The most common attacks on the data link layer arise from the medium access control (MAC) sub-layer, collisions, and jamming [20]. The analysis of these assaults reveals new information about the timing considerations of MAC protocols in terms of security. In the absence of suitable countermeasures, analysis suggests which group of protocols protects against assaults [21]. The data link layer assures the stability of point-to-point (or point-to-multipoint) connections via multiplexing data frames, data streams, the MAC, and error control.  
2. **Clustered Network Architecture**  
This architecture relies on the \"LEACH protocol\", since it uses clusters to group sensor nodes. \"LEACH protocol\" is an acronym for \"low-energy adaptive clustering hierarchy\". Clustering is implemented in a two-tier structure. Sensor nodes are organized into clusters using this distributed approach. The TDMA (time-division multiple access) plans are created by the cluster head nodes in each individually formed cluster. The energy consumption of a network is reduced because of the data fusion concept. The ability to combine data in this network design makes it incredibly popular. In any cluster, all nodes may access data by interacting with the cluster head. The base station will receive data from all the clusters as mentioned in Figure 4. The process of forming a cluster, as well as the selection of its leader in each cluster, is both independent and autonomous [13].