Wired and Wireless Differences

At the Layer-2 level, wireless and wired network connectivity characteristics completely diverge. This post offers a brief summary of the differences between the technologies.

Wired users i.e. those with laptops or PCs connected via an Ethernet cable to a switch port; can use the entire bandwidth on that cable, it is dedicated. In contrast, Wi-Fi access can be imagined as a single shared switch port where several devices (laptops and phones) compete to use that switch port at any one instant.

Wired Ethernet’s cabling is maintained within an organisation, it is private in other words. Wi-Fi on the other hand, utilizes public, shared radio spectrum. There is always potential for network contention as adjacent business or even our own Wi-Fi equipment, use the same channels and cause interference resulting in brief delays to transmit data (read: a slower network). 

Unlike Wi-Fi, Ethernet supplies full-duplex connectivity meaning attached devices can send and receive data simultaneously. In half-duplex Wi-Fi, only one device can send a frame over the shared medium at any one time. 

Bandwidth. In Ethernet, if your laptop connects at 40Mbps, this is a true representation. Wireless however, if the connected ‘data rate’ shows 130Mbps, this is not your throughput. It may actually be 130Mbps – for a minute, and 12Mpbs the next minute, while still showing 130Mbps, because this is what is "possible." It is easier to understand if you consider the data rate to be a target. Your actual throughput will depend on how many other devices are sharing that same channel you are on, how many chances you get to transmit.

Wired Ethernet does not penalise your distance from the switch. In contrast to this, the position of your device relative to the wireless Access Point is important: the further you are, the slower you go. And because it is a shared ‘switch port’, the slower everyone else goes as well.

Wired Ethernet has a large advantage in that it uses substantially less network overhead, meaning more room for sending and receiving data. For example, not every single data frame needs to be acknowledged at Layer-2 in switched Ethernet, as is mandated in wireless and worse, over a half-duplex medium. This overhead includes non-data frames such as SSID beacon frames which are broadcast ten times per second by each radio in every Access Point. 

This substantial management overhead is necessary in wireless. There is no physical electrical connection (like plugging in a cable) in Wi-Fi to alert a network interface card that it is now able to transmit and receive data. Instead, this ability to detect when it is possible to send a frame over the network is handled with management frames, which are essential and mandatory for a functioning network. But management and control frames occupy valuable medium space and unfortunately do not carry any actual data. Best practise in wireless design is to reduce the number of SSIDs for precisely this purpose. 

Security is another advantage of wired communications. It is a complex task to intercept wired Ethernet. One has to have access to the secure management network or physically wiretap cables. But with wireless being a publicly accessible shared spectrum, network attacks or disruption can occur from distance. One does not need to be inside the network to intercept or intentionally disrupt transmissions within that network.

Broadcast domains also differ. In wired LANs, the broadcast domain is the Virtual LAN (VLAN). Its geographical reach across a wired network infrastructure can be large. As can the numbers of connected devices in the LAN. In comparison, like all radio transmissions the broadcast domain of WiFi is the channel: its signal power and reach. WiFi does not suffer from broadcast storms like wired networks can, hence the lack of spanning-tree protocols. But channel interference, client radio power, and a 'clean' less-busy spectrum to send and receive data are concepts that wired Ethernet does not need to consider.

Network Quality of Service (QoS), where some applications are prioritized over others, also completely differs between 802.3 Ethernet and 802.11 Wireless. In Ethernet, each device has a dedicated connection, QoS mechanisms are very exact. In the world of shared wireless access, there are many variables that affect QoS’s ability to actually provide a positive impact; factors not seen in the wired Ethernet world. 

The principal QoS difference is that wireless is shared; only one device can ‘talk’ at one time – remember just one device has access to that shared switch port. In Wi-Fi, a device’s application priority is assigned a random value to transmit data which, may or may not have a higher random priority over other devices at that point in time. Actual prioritisation of frames is variable.

Do note however that this all occurs in the time realms of milliseconds and microseconds. A wireless network with no QoS and with few devices on it will not degrade your video conferencing call. Also worth noting, QoS is less relevant these days as our video and audio calls occur on the Internet, not totally on an internal network under our control.

It may seem that Ethernet is the winner here. In some cases it truly is the best fit for purpose. In the end though, wireless has unbeatable benefits. 

WiFi awards us a flexibility that Ethernet cables cannot. Smartphones and tablets would not be as valuable to us if they could only operate while tethered to a cable.

Laptops can connect wirelessly at any location there is a wireless access. This is useful, not all meeting rooms will be equipped with all cables necessary to connect every laptop. Neither hotel rooms, conference facilities or airport lounges. It is also essential to connect wirelessly when hotdesking or working from your favourite but perhaps random location.

For a business, costly and time-consuming infrastructure network cabling is reduced. A further benefit: large numbers of network switches are no longer required, since only limited numbers are needed to supply network connectivity to wireless Access Points and other essential services like printers, security cameras or concentrated user groups like Call Centre staff.

There are other protocols that operate at the Layer-2 level. Some are only seen in Ethernet and others only in Wi-Fi. Some are common to both but operate completely differently, like ARP. 

Food for thought, for another day.