Ethernet Switch PCB

Are Uplink Ports Still Needed in PCBs for Ethernet Switches?


We build a lot of networking equipment, and one of the common questions we get asked when designing PCBs for these systems is the relevance of uplink ports. Some of the parts we like to use for commercial networking equipment support both fiber and copper, with fiber or a dual-media port being designated an uplink port. Are these ports still relevant in modern systems?

It all depends, but if you are building a custom PCB that requires Ethernet switch capabilities, such as in defense & aerospace, then you might want to consider using a switch with a dedicated uplink port.

Uplink Ports on Ethernet Switch PCBs

The uplink port on the PCB for an Ethernet switch is a special type of port used for connecting different network devices, particularly when you want to expand your network. Normally, each device in your network connects to a regular port on the switch, like houses connecting to a street. This works well when all communication is within a small group of clients. However, what if you want to connect to a larger network, an uplink port would traditionally be needed, particularly on older switches.

Some of the equipment where these switches might connect could include:

  • Upstream or downstream network switches
  • A router or modem
  • Servers
  • High-capacity serial links
  • Legacy equipment

In the networking equipment we build, whether for embedded computing systems or for data center architecture, some of the switch controller ICs we prefer to use still include the uplink ports. For example, one of our favorites is the old Vitesse line of chips. These tried-and-true devices are great for commercial or industrial deployments requiring up to 2.5G speeds over copper or fiber. They can also be implemented in more aggressive form factors that you might find in a rugged mission computer or mini rack-mount unit.


Ethernet switch PCB

One of our industrial networking products.


In the past, there was a distinction between uplink ports and regular ports because of differences in how they handled network traffic and cable types. Uplink ports were designed to flip the transmit and receive lines, which was necessary when connecting switches with straight-through cables, while regular ports were used for connecting devices like computers and printers.

Not all Ethernet switch ICs have (or need) dedicated uplink ports. There are some reasons to include these, but modern switch ICs can provide scalable implementations without an uplink port. On today’s switches, regular ports on an Ethernet switch IC can be used to connect to other switches via RJ-45 connectors or an SFP/fiber interface on the PCB. This is quite common in many network setups, especially with modern switches that have eliminated the need for designated uplink ports.

Are Uplink Ports Obsolete?

Uplink ports are not entirely obsolete, but their necessity has diminished with advancements in network technology. In most cases, you can use the uplink port on an Ethernet switch as a regular Ethernet port. On the PCB, the same media-independent interface (MII) routing would be used regardless of the port type. This is especially true with modern network switches where the distinction between uplink ports and regular ports has become less rigid due to the advancement in network technology.

If you need to design a networked system that might need an uplink port, here are some key points to consider:

Auto-MDI/MDIX - Modern switches usually have Auto-MDI/MDIX (Medium Dependent Interface/Medium Dependent Interface Crossover) capability. This means the switch can automatically adjust for different types of cable connections, allowing any port (including the uplink port) to be used for connecting regular network devices like computers, printers, or other switches.

SFP connections - Many modern switches have SFP ports labeled as uplink ports. These are not the traditional uplink ports but are designed for fiber optic connections or other types of high-speed network modules. These ports offer greater flexibility and longer range for network expansion, especially in enterprise environments.


Ethernet switch PCB

Many uplink ports are used for fiber links with SFP connectors.


Flexibility of use - If you have a spare uplink port and you're running out of regular ports, you can use this uplink port to connect an additional device. This is common in smaller networks or home setups where you need to maximize the available connections.

Network speed and capacity - In some switches, uplink ports are designed for higher speeds. Using them for regular devices is fine, but if the network is expanded later, you might want to reserve these high-speed ports for high-bandwidth channels between switches.

Legacy equipment - In older network setups that don't support Auto-MDI/MDIX, uplink ports are essential for connecting switches without needing crossover cables. Some older switches and networking devices still in use might require these dedicated uplink ports for proper interconnectivity. This is quite important in military-grade PCBs, which still need to interface with a lot of legacy equipment.

The Verdict

In the past, the higher bandwidth connections might have been reserved for Uplink ports; this is still the case but the link speeds have all increased by factors of 10-100x. For example, if regular ports on a switch support 1 Gbps connections, the uplink port might support 10 Gbps for faster communication with the core network or other switches. This can be important in larger or more data-intensive networks.

While the traditional role of uplink ports has been largely absorbed by the capabilities of modern switches with Auto-MDI/MDIX, they are not completely obsolete. Their use and relevance depend on the specific requirements and existing infrastructure of a network. In many small-scale or modern networks, however, any regular port can effectively function as an uplink port, offering flexibility and ease of connectivity.


Whether you're designing an ultra-rugged aerospace system or feature-rich embedded computing products, make sure your design firm understands how to coordinate with electronics manufacutring services and contract manufacturers to help you produce military embedded systems with maximum quality. NWES helps aerospace OEMs, defense primes, and private companies in multiple industries design modern PCBs and create cutting-edge embedded technology, including power systems for high reliability applications and precision control systems. We've also partnered directly with EDA companies and advanced ITAR-compliant PCB manufacturers, and we'll make sure your next high speed digital system is fully manufacturable at scale. Contact NWES for a consultation.


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