The Role of Network Cables in Data Centers

The Role of Network Cables in Data Centers
In data centers, network cables (also known as twisted-pair cables, such as Cat5e, Cat6, Cat6A, etc.) play a crucial role. Although optical fibers dominate in long-distance and ultra-high-speed transmission, network cables remain an indispensable "vein" in the physical infrastructure of data centers.
Specifically, the role of network cables in data centers is mainly reflected in the following aspects:

1. "Last Three Meters" Access for Servers and Switches
This is the core role of network cables in data centers. Servers are usually placed in racks, and access layer switches (ToR switches) are installed at the top or bottom of the same rack.
Short-distance connection: The distance between the server network card and the ToR switch is usually between 1-3 meters. Network cables can fully handle this, and they are softer and more flexible than optical fibers, making them ideal for such short-distance patch cable connections.
High-density wiring: Network cables are thinner and lighter than optical fibers, making them easier to bundle and route in high-density management racks, saving valuable rack space.
2. Supporting PoE (Power over Ethernet)
This is a unique advantage of network cables compared to optical fibers.
Power supply for devices: In data centers, in addition to servers, there are also numerous IoT devices such as IP cameras, access control systems, wireless APs, environmental temperature and humidity sensors, etc. Network cables can simultaneously transmit data and power through PoE technology, eliminating the need to pull power cables separately for these devices, reducing wiring costs and fire risks.
3. Out-of-Band Management (OOB) and Emergency Channels
Management network: Data center servers usually have dedicated management ports (such as IPMI/iDRAC/ILO). Most of these management ports are RJ45 network ports, connected to an independent management switch. Even if the business network card or operating system of the server crashes, administrators can still remotely restart, reinstall the system, or view hardware logs through this network cable.
High compatibility: During emergency troubleshooting, engineers often carry laptops with only RJ45 network ports or Type-C to RJ45 adapters. Network cables are the most common debugging medium.
4. Cost-effectiveness and Deployment Flexibility
Overall cost low: In short-distance transmission within 10 meters, the overall cost of RJ45 ports, network cables, and patch panels is usually lower than that of optical modules, fiber optic patch cables, and MPO patch panels. For data centers with thousands of ports, this can save a huge budget.
Plug-and-play and easy maintenance: Network cables do not need to worry about end face contamination or the problem of insufficient bending radius causing optical attenuation. Making crystal heads, replacing patch cables, and troubleshooting physical faults have much lower thresholds and costs than optical fibers.
5. Meeting Medium and Low-Speed Business Needs
Although the core backbone network of data centers has moved towards 400G or even 800G, not all traffic requires such high bandwidth.
Storage and backup network: Many traditional NAS, backup tape libraries, printers, or older servers still use 1GbE or 10GBASE-T (10 Gigabit Ethernet) interfaces. Network cables are the only or best choice for their connection to the network.
10GBASE-T popularity: Cat6A network cables can stably support 10Gbps transmission up to 100 meters, making 10 Gigabit Ethernet ports widely used within data centers.
?? Supplementary Note: Limitations of Network Cables
Although network cables play a significant role, in modern large-scale data centers, their role is being squeezed by optical fibers (especially DAC high-speed copper cables and AOC active optical cables). Delay: The delay of electrical port transmission is usually slightly higher than that of optical port.
Distance limitation: Beyond 100 meters, network cables cannot guarantee high-speed transmission and must be replaced with optical fibers.
Summary: In data centers, optical fibers are responsible for the "main artery" of high-speed long-distance transportation, while network cables are responsible for the "capillary vessels" of terminal connections, equipment power supply, daily management, and low-cost interconnection. As long as the RJ45 interface is still retained on the server, network cables will not disappear in the data center.