Each networking device can be configured in different ways. Most types of misconfigurations generate problems within the network, including:
- Poor throughput
- Lack of connectivity
A device can be connected to the network, have a signal, and also be able to communicate to the Internet and to other devices but the performance might be low, in a consistent and easily reproducible way. This can manifest during normal operations, including file transfers or other types of communications with the rest of the network.
When experiencing major configuration issues, the issue might manifest as a complete lack of connectivity, including no link lights on the specific device ports. Sometimes the link lights are on but you still lack any kind of connectivity. This shows that signals are passing through the cable, which indicates that you don’t have a cabling issue but, rather, a port configuration issue on one port or the other. This problem requires an investigation of the device configuration.
There are a number of different settings to consider when configuring a port, such as:
- Speed
- Duplex
- Encapsulation/VLAN
Most of these parameters have to be synchronized on both sides of the link, either by manually configuring them or by enabling port auto-configuration. If detected, this method will send negotiation packets on the link to each device to detect the capabilities on the other end device and commonly agree on the best possible parameters supported by both devices to ensure an optimal transmission. The problem is that sometimes auto-configuration does not select the best parameters, so you should verify this and manually configure the ports according to each specific case.
If you are performing manual configuration on each port, one of the first parameters you have to take care of is the interface speed. This has to be identical on both sides of a link. If you configure it incorrectly on one side, the link might not be operational. Another related setting is port duplex, which can be configured to be either half-duplex or full-duplex. You can configure a link with half-duplex on one side and full-duplex on the other side and even though the link will come up, the throughput will be highly affected because each side is expecting to handle communication in a different way. This will result in collisions that will affect transmission on that particular link. Make sure that both sides use the same duplex settings so that traffic can be sent as efficiently as possible.
If you are operating in an enterprise-level environment, you might need to use different VLANs to segment the traffic. Each switch must be properly configured in this regard so that each switch port is assigned to the correct VLAN.
By examining all the port configuration options presented above and making sure that you have everything synchronized on both ends of a link, you can be sure that the connectivity and throughput of the configured devices will be optimized.