What Is SFP Port of Gigabit Switch?

Updated on Jan 6, 2023 by

FS campus switches

SFP ports, also known as Small Form-Factor Pluggable ports, are essential components found in a variety of network and storage devices including switches, servers, routers, and network interface cards (NICs). These ports cater to diverse networking requirements and are particularly prevalent in large computer network switches. Gigabit switches, in particular, are commonly equipped with multiple SFP ports to enhance network connectivity. But what exactly is the role of an SFP port on a Gigabit switch, and how does it differ from an RJ45 port? This article will explain the essential information about SFP ports on a Gigabit switch.

What Is SFP Port on a Gigabit Switch?

The SFP port on a Gigabit switch is a slot designed for use with small form-factor pluggable (SFP) connectors to enable data transmission. It offers high speed as well as physical compactness. The SFP port enables optical or copper links on a Gigabit switch through the insertion of the corresponding SFP modules (fiber SFP or copper SFP).

The only difference between the SFP port and the electrical port link lies in the physical layer (media). This means an SFP port can house an SFP module with an optical port or an electrical port. Thus, fiber or copper cables are needed to realize data transmission.

When an SFP module is inserted in a Gigabit switch with electrical ports, network cables such as Cat5e/Cat6/Cat7 cables must be used for data transmission. However, when an SFP module is plugged in a Gigabit switch with optical ports, fiber optic cables have to be used to support connections. Therefore, RJ45 SFP modules are generally used for short-range uplinks to connect an all-SFP distribution switch to an all-copper edge switch. While fiber SFP modules are most commonly used for a high-speed fiber uplink over longer distances.

You may be interested in Gigabit Switch: How Much Do You Know?

Common Types of SFP Port

SFP Combo Ports

The combo port is a versatile interface that supports both copper and optical SFP connections. It serves as a compound port, accommodating two different physical ports: an RJ45 port and an SFP port. Users have the flexibility to use either the RJ45 port or the SFP port based on their requirements.

However, it's important to note that the two different SFP ports cannot be used simultaneously. Each SFP combo port functions as a single interface, providing a choice between two connections. One option is the RJ-45 connection for a copper Ethernet cable, while the other is the SFP connection for a fiber optic cable. For example, when a combo SFP port is utilized in a Gigabit switch, the corresponding copper port cannot be used, and vice versa.

FS, the professional provider of communication and high-speed network system solutions, offers the S5810-28TS switch. This advanced switch has 4x 1G RJ45/SFP Combo ports and 4x 1G/10G SFP+ ports, delivering flexible connectivity options and better performance.

The FS S5810-28TS Switch

SFP Uplink Ports

An uplink port is a port for aggregation to higher links, which is designed for inner-switch connection with a standard straight-through cable instead of a crossover cable. Thus, an uplink SFP port can connect to a regular port of another device.

In a traditional 3-tier network topology, there are access layer, distribution layer, and core layer from bottom to top. This means there are access, distribution, and core switches. Usually, a SFP downlink port is used for connecting to end devices such as laptops and PCs.

Thus, an uplink SFP port is used for connecting to a higher layer in the network topology. This also means connecting to a higher speed switch such as 10G SFP+, 25G SFP28, 40G QSFP+, and 100G QSFP28.

Taking the FS S3700-24T4F switch as an example, it has 4x 1Gb SFP uplink ports, providing high bandwidth, flexible connection options, and scalability.

The FS S3700-24T4F Switch

Why SFP Ports Matter

Long-Distance and High-Speed Data Connections

SFP ports on switches are ideal for long-distance transmission and high-speed data transfer. When it comes to connecting devices located in different buildings or distant spots, SFP ports become a game-changer. By utilizing fiber optic cables, these ports allow data to travel over significant distances effortlessly. This makes them invaluable in scenarios where seamless connectivity is needed across large physical areas. Moreover, SFP ports excel in facilitating high-speed data transfer, which is crucial for bandwidth-intensive tasks like streaming high-definition movies or operating data centers. These ports provide the necessary bandwidth and performance to ensure uninterrupted and smooth operations for such demanding applications. With SFP ports, heavy-duty data transmission can be achieved without compromising speed or reliability.

Interoperability and Compatibility

SFP ports offer great flexibility and compatibility due to their ability to accommodate a wide range of SFP transceiver modules. This adaptability enables them to work with different types of networks and protocols, making it easier to integrate SFP ports into existing infrastructure and ensure smooth interoperability.

Redundancy and Failover Capabilities

SFP ports can be utilized to establish redundancy and failover mechanisms within networks. By connecting additional SFP ports to various switches or routers, a backup connection can be created. This ensures network continuity and minimizes downtime in the event of a primary connection failure.

SFP Port vs. RJ45 Port on a Gigabit Switch

In addition to SFP ports, Gigabit switches generally come with built-in RJ45 ports to allow plug-and-play Ethernet copper cables. Here we will discuss on differences between SFP ports and RJ45 ports on a Gigabit switch.

Connection Types

It’s the most basic difference which decides many other features of RJ45 ports vs SFP ports, so we put it at the very beginning. The RJ45 port only supports Ethernet cables (Cat5e/Cat6/Cat7) for 1Gbit/s transmission, and the distance is limited to 100m (330ft). Thus, it is commonly used to connect a computer or a router. So 1000BASE-T switch with RJ45 ports can be used in data centers for server switching, LANs, for uplinks from desktop switches or directly to the desktop for broadband applications.

In terms of SFP switches, SFP ports are more versatile and accept fiber SFP modules with fiber optic cables (both single-mode and multimode), as well as copper SFP modules with Cat5e, Cat6, Cat7, Cat8 cables. This means SFP ports support more types of communication cables and longer reaches of links.

Maximum Distance

The maximal transmission distance varies a lot due to the connections RJ45 and SFP ports used respectively. RJ45 ports support a maximum distance of 100 meters, making it more than enough for a home or small office network.

SFP ports allow greater distances. MMF cables connected to the SFP port can reach up to 550-600 meters and SMF cables 150 kilometers. If connected with a Cat5 cable, the SFP port follows a 100-meter limitation.

For short-distance links on a Gigabit switch, there is no difference between using an SFP port or RJ45 port to interconnect Ethernet switches. If you don’t plan to connect the server through optical links in the near future, you will not need an SFP port switch and you can stay with standard 1000BASE-T.

 Feature   RJ45 Ports   SFP Ports
 Physical Connection  Uses RJ45 socket connection  Uses hot-swappable SFP module connection
 Transmission Speed  Typically supports 10/100/1000 Mbps speeds  Can support various speeds such as 1 Gbps, 10 Gbps, etc
 Maximum Transmission Distance  Short distances (typically within 100 meters)  Depends on the type of fiber and SFP module used
 Flexibility  Suitable for connecting directly to computers, servers, and other devices with copper cable connection  Fiber optic or copper cable connections can be achieved by replacing different types of SFP modules
 Application Scenarios  Suitable for short-distance local area network connections, such as offices, home networks, etc.  Suitable for long-distance transmission, high-speed data transfer, and flexible connection requirements
 Cost  Relatively low, suitable for regular network connection needs Relatively high, suitable for high-speed, long-distance transmission, and specific application requirements


SFP ports expand the connectivity of Gigabit switches, allowing them to connect to a wide range of fiber and Ethernet cables. These versatile ports support both RJ45 SFP modules and fiber SFP modules, offering flexibility in network configurations. Combo and uplink SFP ports further enhance customization options based on specific application requirements, combining power and flexibility.

FS provides a comprehensive selection of swicthes, copper and fiber SFP modules that are fully compatible with major market vendors. Click FS.com for professional networking solutions.


Related Articles:

Understanding SFP and QSFP Ports on Switches

A Guide to Choose the Right FS S5800 Series Switches

FS S5800-48F4S 10GB SFP Switch for Data Center Access Network

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