Network Access Layer, also known as the Data Link Layer, is the second layer of the OSI model. It is responsible for providing a reliable link between devices on a network by controlling the flow of data, managing access to the physical media and providing error detection.
The Network Access Layer issues are problems that occur at this layer of the OSI model, which can have an impact on the performance and functionality of the network. These issues can include problems with the physical components of the network, such as cables and NICs, as well as issues with the protocols and algorithms used to control the flow of data. Examples of Network Access Layer issues include:
- Input Errors: These occur when a device receives a packet that is corrupt or otherwise unable to be processed. Input errors can be caused by a variety of issues, such as a malfunctioning NIC, a bad cable, or a problem with the receiving device's processing capabilities.
- Runts: Runts are packets that are smaller than the minimum packet size, typically 64 bytes. These packets are often the result of a collision or a malfunctioning NIC.
- Giants: Giants are packets that are larger than the maximum packet size, typically 1518 bytes. These packets can be caused by a malfunctioning NIC or a software bug.
- CRC (Cyclic Redundancy Check): This is a type of error detection used to ensure that data has not been corrupted during transmission. If a packet's CRC value does not match the value calculated by the receiving device, it will be discarded as an error.
- Output Errors: These occur when a device is unable to transmit a packet properly. Output errors can be caused by a variety of issues, such as a malfunctioning NIC, a bad cable, or a problem with the network's routing.
- Collisions: Collisions occur when two or more devices attempt to transmit on the same network segment at the same time. When this happens, the packets are corrupted and must be retransmitted, which can lead to decreased network performance.
- Late Collisions: Late collisions occur when a collision is detected after the packet has already been transmitted for more than the first 64 bytes of packet. This can be caused by a duplex mismatch, a cable problem, or a problem with the switch or router.
