SFP vs RJ45 : What's the difference?

 

Difference between RJ45 and SFP port in 1000Mbps Connections
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. RJ45 ports support RJ45 Ethernet cables such as Cat5, CT6, etc., commonly be used to connect a computer or a router. What are SFP ports used for? 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.

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.

Features	SFP Port	RJ45 Port
Connection Types	·  copper SFP module + RJ45 Ethernet cable (Cat5e/Cat6 or higher) ·  ·  fiber SFP module + fiber optic cable (SMF fiber / MMF fiber) ·	RJ45 Ethernet cable (Cat5e/Cat6 or higher)
Max Distance	MMF (550m) / SMF (150km) / RJ45 Ethernet cable (100m)	100m (330ft)
Data Rate	1000Mbps (1G)	1000Mbps (1G)

 
 
Actually, here comes another related network switch port type, which is the combo port. For example, this S5800-8TF12S switch comes with 8 x 1G SFP/RJ45 combo ports, and 12x 1G/10GE SFP+ ports. Compared to SFP/RJ45 ports, these 8 combo SFP/RJ45 ports allow users to use either SFP port or RJ45 port at a time for short-distance connections.
SFP (Small Form-factor Pluggable) and RJ45 are two types of interfaces commonly used in network switches, routers, and other networking equipment. They serve different purposes and have distinct characteristics:
1.Nature of Interface:
SFP: SFP is a compact, hot-pluggable transceiver used for both telecommunication and data communication applications. It converts electrical signals to optical signals and vice versa, making it useful for optical fiber connections.
RJ45: RJ45 is a physical interface mainly used for connecting twisted pair cables, typically Ethernet cables like Cat5e, Cat6, etc. It's a widely recognized standard for wired local area networks (LANs).
2.Media Type:
SFP: Typically used with optical fiber cables which can span longer distances and have various advantages such as immunity to electromagnetic interference.
RJ45: Used with copper-based twisted pair cables. These cables are generally limited to shorter distances compared to optical fiber, typically up to 100 meters for Gigabit Ethernet.
3.Speed:
SFP: Depending on the module type, SFP can support speeds from 100 Mbps to 10 Gbps or more.
RJ45: Commonly used for 10/100 Mbps (Fast Ethernet) and 1 Gbps (Gigabit Ethernet) connections, though 10 Gbps over copper (10GBASE-T) is achievable with newer, high-quality Cat6a or Cat7 cabling for shorter distances.
4.Distance/Reach:
SFP: Fiber optic SFPs can cover a range from 500 meters to several kilometers, depending on the type of module and fiber used.
RJ45: Limited to 100 meters for 1 Gbps connections. For 10 Gbps over copper, the distance is usually limited to 30-50 meters, depending on the cable quality.
5.Flexibility:
SFP: Provides flexibility as different SFP modules can be used within the same slot, allowing for a mix of different speed and distance combinations.
RJ45: Is a fixed interface. When a device has an RJ45 port, it can only be connected to copper twisted pair cables with RJ45 connectors.
6.Application:
SFP: Commonly found in enterprise-level switches, routers, and other networking equipment where flexible connectivity options and longer distances are required.
RJ45: Ubiquitous in both home and enterprise environments, especially for local area connections within a building or campus.
When choosing between SFP and RJ45, it's crucial to consider the specific requirements of the network, such as desired speed, distance, and the types of devices being connected.
 
 

What is sfp？

SFP stands for "Small Form-factor Pluggable." It is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. The SFP interface connects network devices, such as switches, routers, and firewalls, to fiber optic or copper networking cables.
Key characteristics of SFP include:
1.Versatility: SFP modules are available to support a variety of different communication standards including Gigabit Ethernet, Fibre Channel, SONET, and others.
2.Hot-pluggable: This means that the module can be replaced without turning off the device, allowing for upgrades or changes to the network without any interruptions.
3.Distance/Reach: Depending on the type of module and fiber used, SFPs can transmit data over distances ranging from short links (up to 10 meters using copper modules) to 120 kilometers or more using long-distance fiber modules.
4.Types: There are various types of SFPs available depending on the application, including:
· SX: Short range up to 550 meters
· LX/LH: Long range up to 10 kilometers
· ZX: Extended range up to 80 kilometers
· CWDM and DWDM: For wavelength-specific networks
· Copper/Twisted Pair: For applications where copper cables are preferable
5.Multi-Source Agreement (MSA): SFP is defined by an industry-standard agreement, which means that systems which use SFP slots can accept any SFP module, regardless of brand, as long as it fits within the MSA standards.
SFP has been succeeded by faster standards, notably the SFP+, which supports 10 Gbps, and QSFP/QSFP+, which can support even higher data rates. However, SFP remains a popular choice for 1 Gbps connections and is widely used in enterprise networks and data centers.
 
 

What is rj45?

RJ45, short for Registered Jack 45, is a standard type of physical connector for Ethernet cables, commonly used in networking. The "RJ" stands for "Registered Jack," a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long-distance carrier.
Key features and information about RJ45:
1.Pin Configuration: An RJ45 connector has eight pins, making it suitable for 8P8C (eight positions, eight contacts) modular connectors. Each pin is used for a specific color-coded wire in standard Ethernet cables.
2.Usage: RJ45 connectors are commonly used in Ethernet networking for both home and business setups, connecting computers, routers, switches, and other network devices.
3.Categories: Ethernet cables with RJ45 connectors come in various categories (Cat), such as Cat5e, Cat6, and Cat7. Each category offers different levels of performance, especially concerning data transfer rates and bandwidth.
4.Physical Appearance: The RJ45 connector looks similar to a standard telephone connector (RJ11), but is larger in size. An RJ45 connector can easily be recognized by its 8 pins and its wider size compared to the RJ11.
5.Crossover and Patch: When connecting similar devices (like two computers) without a switch or hub in between, a crossover cable might be required. This type of cable has certain pairs of wires swapped at one end (usually the green and orange pairs in T568A/T568B standards). For most other applications, a straight-through or patch cable is used.
6.Standard Wiring: The two main standards for RJ45 wiring are T568A and T568B. The position of the colored wires is slightly different in both standards, but they perform the same function. The choice of standard often depends on regional or organizational preferences.
The widespread use of RJ45 in Ethernet networking makes it one of the most recognized and used connectors in IT and telecommunications.
 
 

Considerations for Choosing RJ45 or SFP Port

Now we know when the link distance is over 100 meters, SFP port with fiber SFP module must be considered instead of RJ45 Ethernet port with Ethernet cable. People may also want to learn about SFP 1000Mbps vs RJ45 1000Mbps when the connection is within 100 meters. Here are some other principles when deciding to use RJ45 port or SFP port.
· Security. Using fiber SFP module is more secure than Cat5e/Cat6 RJ45 Ethernet cable in some worse circumstances. RJ45 cable uses electric current so it can be easier to catch on a fire/lightning while fiber SFP module has no such problem.
· Reliability. Fiber is often considered more reliable due to its properties. RJ45 Ethernet cable has the risk of EMI (Electromagnetic Interference) since it uses electric signals which can be easily affected by some external elements, such as high voltage.
· Latency. When connecting devices at a considerable distance, SFP ports have a lower latency compared to RJ45 ports that maybe give a worse service.
· Power Consumption. SFP ports have lower consumption compared to RJ45 ports. Especially in a large network, the consumption difference is going to be far more obvious.
· Future Network Upgrade. If you’re planning to move to higher bandwidth, e.g. 10 Gbps, in the near future, SFP ports that support fiber optic cable are more future-proof compared with Cat5e/Cat6 RJ45 Ethernet cable.
· Cost. Since RJ45 Ethernet port and SFP port actually run at the same speed, choosing RJ45 ports to connect Ethernet switches might be more economical as Cat5e/Cat6 cable is lower-priced than the SFP connection with both transceivers and corresponding cables.
 
 
10G SFP+ to RJ-45 Transceiver Types and Max Distance
10G Copper RJ45 transceivers can have different capabilities, based on the data rate requirements and can be used with Cat 5e and newer Cat6a/7 category copper cables.
We have available several hardware options for RJ-45 to SFP+ Transceivers as below:

Below would be more details on each of provided hardware version:

1) 10G-SFP-T version (002):
This transceiver supports following data rates: 10 Gbps, 5 Gbps, 2.5 Gbps and 1 Gbps. Maximum Cat 6a/7 cable distance till 30 meters. It has the following specifics:
-It can be inserted only in 10G SFP+ port
-Device which it connects has to be with 10 Gbps, 5 Gbps, 2.5 Gbps or 1 Gbps interface respectively

2) 10G-SFP-T2 version (001):
This transceiver supports following data rates: 10 Gbps, 5 Gbps, 2.5 Gbps and 1 Gbps. Maximum Cat 6a/7 cable distance till 30 meters. It has the following specifics:
-It can be inserted only in any of 10 Gbps, 5 Gbps, 2.5 Gbps and 1 Gbps ports
-Device to which it connects to can be 10 Gbps, 5 Gbps, 2.5 Gbps or 1 Gbps fixed speed interface respectively. In other words: the data rate between 10G-SFP-T2 and the other end must match.

3) 2.5G-SFP-T version:
This is a completely different hardware version transceiver than 10G-SFP-T. It can only be used for 2.5 Gbps Ethernet. With Cat 5e/6a/7 cable it can reach 30 meters.

4) 10G-SFP-T-80 version:
This transceiver supports following data rates: 10 Gbps.
Maximum distance Cat 6a 30 meters and Cat 7 till 80 meters. It has the following specifics:
-It can be inserted only in 10G SFP+ port;
-Device which it connects to has to be with 10G interface;
-It can reach 80 meters via Cat 7 cable.