LAN on Motherboard versus Network Interface Card - which is best ?

The ongoing industry trend of doing away with an add-on card card and putting the logic necessary for Ethernet Network connectivity onto the main board of the computer itself has proven to have several advantages and disadvantages over discrete add-in cards :

Advantages of Integrated Networking

• Lower cost to end user or system integrator
• Product Appeal to manufacturer/marketing bullet point
• Reduced power consumption
• Improved thermal performance and airflow inside the system chassis
• More Consistent reliability and compatibility compared to numerous variation of add in network cards
• Better Out of the Box experience of the end user
• Optional Remote Management support, such as PXE boot without an additional costly Flash ROM to store boot code

Disadvantages

• Should the onboard networking fail in any way, an add-in card is still required to replace the lost functionality
• If the onboard networking fails, and it is not possible to add a replacement network interface, such as in a Small Form Factor PC or Mobile platform, the main board must be returned for repair
• End User or purchaser has little choice of supplier the onboard networking - a specific vendor may be desired due to compatibly and validation with existing equipment and infrastructure, such as switches
• Add in cards are a  Value Add Item for Original Equipment Manufactures and System Integrators, both on a parts and labour basis

On a performance basis, the Integrated and add-in solution should be on par as the same components for the different networking layers are used. Since integration can infinitely vary such as differences or tolerances in the way components are wired on the main board, or compatibility of certain components with different Ethernet switches, it can be hard to offer performance metrics

If networking is important to you when selecting components for a potential purchase, such as a new main board. Make sure there are additional slots so that a PCI or PCI-E network card may be fitted in the future in case the onboard LAN port fails or there is a compatibility issue with ones network.

It is much easier and cheaper to install an existing networking card or purchase a cheap network card, than to change a main board under warranty or at cost to the user, and ensures the least possible downtime.

While using a Wi-Fi or USB based Ethernet network solution is a solution if a system has no available expansion ports, these are not a 100% replacement for traditional Ethernet networking

This advice might be brushed off by experienced system builders with comments such as "LAN ports rarely break", it is a crucial point to consider and not to be overlooked, especially if networking is being used 24/7, cable is re-plugged frequently or system is in a marine environment and subject to rust and corrosion

We at NitroWare.net have seen a number of issues that can occur with onboard networking ports over the years both with contemporary modern offerings and older offerings

• Ethernet port pins may deform from poor conforming RJ-45 plugs or mistaken insertion of a non RJ connection such a a USB Type -A plug, a common mistake.
• Connector pins may deform from re-plugging
• Marine environment such as near sea-sides or aqua rusting or corroding the exposed I/O panel and connections of a main board or system
• Component failure on the motherboard itself  such as Timing Crystals or south bridges, resulting in malfunction of the networking controller. This is usually do to poor selection of components by a vendor.
• General Compatibility and reliability issues with the onboard solution, such as failure to establish a link, inability to keep a link up, and repetitive re-linking with the switch/hub. Such symptoms can be due to component selection or failure of components in the physical layer of the networking topology.

Many of these issues can also arise on add-in cards, but as we mentioned prior, in an integrated scenario on a main board, any failure or issue with the integrated networking is critical