Switch Cascading: With SFP Port or Standard RJ45?

Gigabit switch that offering greater speeds and compatibility has gained in much momentum in the field of networking. And with the unceasing demand for more bandwidth, network will grow to the point that we need to connect several gigabit switches together. Switch cascading is one of the options to link more than one gigabit switches. But here comes the problem: should I cascade switches via a SFP port (copper SFP module or fiber SFP module) or just through standard RJ45 ports? Is there any difference in regard to the speed and distance. This is we’re gonna explore in the article.

What Is Switch Cascading?

Cascading more than one switches enables us to have multiple ports interconnecting each of the switches in the group. But they are configured and managed independently. Switches that are cascaded together should all support Spanning Tree Protocol (STP), in order to allow redundancy and to prevent loop. Generally switches of any models or from any manufacturers can be cascaded. There are two options to cascade switches, either use copper SFP (1000BASE-T SFP) and fiber SFP port or via standard RJ45 port on the Gigabit switch.

SFP Port on Gigabit Switch

SFP port enables Gigabit switches to connect to a wide variety of fiber and Ethernet cables in order to extend switching functionality throughout the network. The SFP port allows the switch to connect to fiber cables of different types and speeds via fiber SFP module, or even connect to Ethernet copper cables through copper SFP module. As hot-pluggable I/O devices, both fiber SFP and copper SFP models can be used on a wide variety of products and intermixed in combinations of 1000BASE-T, 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-EX, 1000BASE-ZX, or 1000BASE-BX10-D / U on a port-by-port basis.

SFP Module Type
Cable Type
Transmission Distance
Maximum transfer rate (distance of 1000m)
Copper SFP Module
Cat5 network cable
1000 Mbps/1 Gbps
Fiber SFP Module
Duplex LC
Fiber patch cable
≥ 100m
1000 Mbps/1 Gbps

RJ45 Port on Gigabit Switch

RJ45 ports are built-in ports in Gigabit Ethernet switch. To connect two RJ45 ports, Cat5e or Cat6 copper network cables are generally adopted. Here lists the specification of each network cable.

Max Transmission Speed (at 100 m)
Max Bandwidth
Cat 5e
1000 Mbps / 1 Gbps
100 MHz
Cat 6
1000 Mbps / 1 Gbps
100 MHz

Cascading Switches: SFP Port vs. RJ45 Port

So, here we have literally three options to cascading two switches:

  • Connect SFP port of the two switches via fiber SFP module and fiber patch cable
  • Connect SFP port of the two switches via copper SFP module and copper network cable (Cat 5e/Cat 6)
  • Connect the built-in RJ45 ports via Cat 5e or Cat 6 network cable

sfp port fiber sfp copper sfp

For fiber SFP port vs. copper SFP (or bulit-in RJ45 ports ), the benefit of using the fiber SFP port for switch cascading is that you will have more Ethernet ports available for your end points connections. Besides, both RJ45 ports and copper SFP module use electric signal to transmit data, fiber SFP module, however, uses light signal can tolerate longer distances and is less prone to interference. The other criteria is that fiber SFP module in most Cisco SFP switches is capable of higher speeds than the normal copper ports.

While for copper SFP vs. RJ45 ports, things become far easier. As they both utilize electric signal to transfer, the two options are basically the same. Except that the copper SFP module would generate extra costs and increase installation time. So when it makes sense to use copper SFP module instead of RJ45 ports? Only for cases where you need to connect between an all-SFP distribution switch and an all-copper edge switch. The reason the switches have SFP slots is to support connecting to a fiber optic network, either to talk to other fiber optic gear or especially to connect over distances that copper transmission can’t support at gigabit speeds.


It is thus clear that the choice between fiber SFP vs. copper SFP vs. Rj45 port when cascading switches actually depends on your specific cabling environment, and where the cable run is going. FS.COM offers a broad range of copper and fiber optic transceivers that fully compatible with major vendors on the market, which makes us the vendor of choice for optical network components and solutions. For any further information, please visit www.fs.com or contact us directly via sales@fs.com.

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Mini GBIC vs SFP: Is It the Same?

We’ve got very familiar with GBIC transceiver: short for gigabit interface converter, it is developed in 2000 as a hot swappable transceiver that commonly used in Gigabit Ethernet and Fiber Channel. But as the demand for higher bandwidth and transmission speed keeps accelerating, more ports are needed to be fit in a line card. So Mini GBIC module is developed to provide more interface in the same line card. Mini GBIC is a smaller version that only half the size of GBIC transceiver. So what exactly is Mini GBIC module? Mini GBIC vs SFP: Is It the same? This article will handle all the confusions for you.

What Is Mini GBIC Transceiver?

Mini GBIC, also called SFP transceiver (SFP means small form factor) was announced in 2001, it has the same functionality with former GBIC module but built with a smaller form factor. Mini GBIC and SFP transceiver actually refers to the same thing, and they are interchangable. Mini GBIC transceiver is a compact, hot-pluggable module that can be installed and removed while the switch is powered on. Mini GBIC provides flexibility for utilizing fiber Gigabit connections in both data and telecommunication applications. So the shipment of Mini GBIC had soon outgrown GBIC transceiver and secured its position in Gigabit SFP based network.

mini gbic vs sfp transceiver

What Is a Mini GBIC Used For?

Mini GBIC transceivers allow technicians to easily configure and upgrade electro-optical communications networks. It is a plug-in module that can be removed and replaced without turning off the system. Mini GBIC transceiver is typically employed in fiber optic and Ethernet systems for high-speed networking. The data transfer rate is one gigabit per second (1 Gbps) or more. Mini GBIC are designed for high performance integrated duplex data transmission over optical fiber. designed to support SONET, Gigabit Ethernet, Fiber Channel, and other communications standards.

Mini GBIC Transceiver Classification

Mini GBIC can be classified into different groups according to data rate, operating wavelength, transmission distance and etc.

Divided by rate :155M/622M/1.25G/2.125G/4.25G/8G/10G,155M and 1.25G market is more used.

Divided by wavelength : 850nm/1310nm/1550nm/1490nm/1530nm/1610nm.

  • The 850nm wavelength is SFP multimode, and the transmission distance is up to 550 m.
  • 1310/1550nm is SFP single-mode, and the transmission distance ranges from 2 km to 80 km.

The bare Mini GBIC module basically has no difference if they have no mark, so the manufacturers make different colors of pull ring to distinguish them.

  • Black pull ring is multi-mode, the wavelength is 850nm;
  • Blue is the 1310nm module;
  • Yellow is the 1550nm module;
  • Purple is the 1490nm module and so on.

Divided by distance: Mini GBIC transceiver can also be classified by different transmission distance, see the following table:

mini gbic or sfp module types


Mini GBIC transceiver, with its small and low-cost advantages to meet the needs of high-density transmission, has replaced GBIC transceiver to become mainstream in data center. FS.COM offers a broad range of Mini GBIC transceiver that fully compatible with major brands on the market. Each of our optical transceivers is tested on the brand switch in strict environment to ensure performance and reliability. For more details, please visit www.fs.com or contact sales@fs.com.

Related Article: GBIC vs SFP: When It’s Best to Use GBIC and When to Use SFP
Related Article: SFP Module: What’s It and How to Choose It?

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Can GPON SFP Be Plugged Into My Own Switch?

Fiber has been introduced to average homes and businesses for a spell and it has different names from different service providers: Google Fiber, Verizon FiOS, AT&T GigaPower, UFiber, etc. GPON is one of the key technologies that are used to deploy these fiber-based access networks (FTTx). Though it is called GPON from its emergency to its prosperity, some details in utilizing GPON services have changed. Early GPON adopters may still remember the doubled devices the provider installed in their houses. But now things seem to be easier in adopting GPON for both the service provider and the end user. Optical Network Termination (ONT) or Optical Network Unit (ONU) GPON SFP module is the new kid in GPON applications and customers are not familiar with them enough.

GPON SFP module

ONT/ONU: From Optical Modem to GPON SFP Module

What is your ONT like? Previous ONT is an optical modem. It usually has an SC/APC port for connecting the SC fiber cable, some fast Ethernet or gigabit Ethernet (LAN) ports. Some has a phone port for VoIP service. Apart from a modem, the service provider also lends an IP access router to the customer. If there’s television service required, a Set-Top-Box or a video recorder is also needed. Some Internet service providers (ISPs) put an integrated ADSL router (modem + router).

optical modem with an SC port

ONT/ONU GPON SFP module is a bidirectional single-mode SFP module with a simplex SC receptacle. The adoption of GPON ONT SFP is considered a significant improvement in GPON optical networks. Compared with its predecessor, the SFP format has much smaller size than traditional ONTs/ONUs. Besides, it cut down the equipment that need to be provided by the ISP, which also make it easier for customers to connect their diverse data, voice and video devices.

Can I Use GPON SFP Module in My Own Switch?

Since the GPON ONT has been condensed with a small form-factor pluggable (SFP) packaging, can it be plugged into the end users’ switch/router as other SFP modules do? In most scenarios, the answer is yes. Several reasons can prove how it is possible.

Firstly, the GPON ONT module is in standard SFP format. Such a packaging allows the GPON ONT module to be plugged into any standard MSA-compliant SFP port. This is the basis for its use in other devices not provided by the ISP.

Secondly, it has been stated by the vendors of GPON ONT SFP modules that their ONT SFP can be used in a wide range of wired and wireless products with SFP port, such as Huawei MA5671A ONT SFP. The datasheet of this GPON ONT SFP says it can be plugged into the SFP port of any customer- or carrier-owned terminals, including switch and router. Also it can be used in WiFi access point (AP) with SFP slot and to transmit wireless traffic over GPON.

Thirdly and most importantly, there are home users or engineers who have tested PON ONT SFP modules in different networking devices. During the installation of GPON services, some users required to use their own routers instead of the router provided by the ISP. It was approved by the ISP and they whitelisted the users’ router so that it can interoperate with the OLT in the Central Office. What the users needed to do was just to plug the GPON ONT SFP in the SFP port of the router and then plug the SC fiber patch cord into the receptacle of the GPON ONT SFP. The only hard point in this process is to get the support from your ISP. (If you are interested, these using cases can be easily found on google.) In addition, the test of GPON ONT SFP modules from different vendors has been down as well. Most manufacturers’ GPON SFPs can be used in any switches/routers/gateways with SFP ports. But this is the ideal case, not given that some picky original switches/routers may refuse to or the GPON ONT SFP is not a quality one.


GPON SFP is a small transceiver module that allows effective and low-consumption transmission over GPON. And the use of GPON ONT/ONU SFP module at the customer side is even more convenient than previous installations. Theoretically and practically, a standard GPON ONT SFP can be used in any switches/routers/gateways/APs with standard SFP ports. The only question is to get the approval of your ISPs.

Related Article: ABC of GPON SFP: Understanding GPON OLT / ONU / ONT SFP Module

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How to Build a Data Center of 40G Networking With 32-Port 40G Switch?

Earlier before this year we did not anticipate the shared bikes would be widely spread all over the world, but now at the end of this year they are already everywhere. Shared bike is one of the instances of the Internet of Things (IoT), and there are many other applications that have witnessed the development of network-dependent technologies, such as self-driving cars, smart mobile phones/pads, etc. They are all calling for high bandwidth and low latency. But the old network infrastructure of data centers is not capable enough in such an environment, especially for those data centers that should deal with a huge amount of traffic. So some data centers are upgrading from 10G networking to 40G networking by using 40 Gigabit Ethernet switch, of which a 32-port 40G switch is a typical choice.

Limits of Old Data Center Network Infrastructure

What are the limits of old data center network infrastructure? In the past, the major traffic in data centers is in the north-south direction. As for data center switches, it is enough to use 10G uplink ports between the Top of Rack (ToR) switches and the aggregation switches. But as new applications and services rapidly emerge, the traffic between the end user and the data center is increasing, and the traffic in the east-west direction within the data center is increasing as well. Issues of congestion, poor scalability and latency occur when data centers keep using traditional network infrastructure.

The New Fabric for Data Center 40G Networking With 32-Port 40G Switch

In order to meet the requirements of the ever increasing network applications and services, data centers are constantly seeking better solutions. The primary problems are about bandwidth and latency. So one important thing is to upgrade from 10G networking to 40G networking. Since the 40G switch price and the 40G accessory price have dropped a lot, it is feasible to deploy 32-port 40G switches in the aggregation layer. In order to reduce the latency, it is wise to adopt the new spine-leaf topology compared with the old topology.

Scaling Example by Using 32-Port 40G Switch

A network based on the spine-leaf topology is considered highly scalable and redundant. Because in a spine-leaf topology, each hypervisor in the rack connects every leaf switch. And each leaf switch is connected to every spine switch, which provides a large amount of bandwidth and a high level of redundancy. In a 40G networking, it means every connection between the hypervisor and the leaf switch, the leaf switch and the spine switch is both at 40G data rate. In a spine-leaf topology, the leaf switches are the ToR switches and the spine switches are the aggregation switches.

data center 40G networking in spine-leaf topology

One principle in spine-leaf topology is that, the number of leaf switches is determined by the number of ports in the spine switch, at the same time the number of the spine switches equals the number of connections used for uplink. For a 32-port 40G switch like FS.COM N8000-32Q, it can have a maximum of 32 40G ports, but some ports should be used for uplinks to the core switches. In this case, we use 24 40G ports for connectivity to the leaf switches, meaning there are 24 leaf switches in each pod. The leaf switch we use is the FS.COM S5850-48S6Q, a 48-port 10Gb switch with 6 40G uplink ports. Each leaf switch has 4 40G uplinks to the spine switch. Then each spine switch connects to the two core switches.

data center 40G networking with 32-port 40G switch

Better Enhance the 40G Networking by Zones

This new data center fabric by using 32-port 40G switch is an improvement in bandwidth and latency, but it is not perfect either. For every network switch, it has limits on its memory, including the memory of MAC addresses, ARP entries, routing information, etc. Particularly for the core switch, the number of ARPs it can store is still limited compared with the large number it has to deal with.

Therefore, there’s need to split the network into zones. Each zone has its own core switches, and each pod has its own spine switches. Different zones are connected by edge routers. By adopting this design, we are able to expand our network horizontally as long as there are available ports on the edge routers.

data center 40G networking with 32-port 40G switch optimized by zones


The transformation of data centers is mainly due to the demand of the users. The increasing amount of networking applications and traffic pushes data centers to evolve from old fabric to new fabric. So some data centers have changed from 10G networking to 40G networking by using 40 Gigabit Ethernet switch as spine switch like 32-port 40G switch. And better optimized design is adopted to ensure the desired performance of the new 40G network.

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Stack Switch: Optimize Your Network Performance to the Maximum

Stacking switch is a common technology used in network design, especially when large numbers of ports are required in data centers or large size networks. Stack switch not only provides high performance, but also maximizes network scalability and simplify network management. That’s why stackable switches are popular among network builders. Then what is stack switch? What’s the common way for switch stacking in the market?

What Is Stack Switch?

Stack switch, also called stackable switch by vendors, allows several switches to stack via specific stackwise port or uplink port. Traditionally the switches stacked together usually is limited to the same series of network switches. Mixed switch stacking is allowed for today’s switches. The number of stacked switches is often determined by switch brand. For example, Cisco 3850 stack switch can have a maximum of eight switches to be stacked, while Dell N4000 series stack switches are up to twelve. When switches are stacked, all members in this stack share the same IP address and can be managed as “one unit” through the CLI (command line interface) or embedded Web interface, which offers great convenience for network administrators without lowering its performance.

FS stack switch

Usually stack switches come with fixed configuration like 12, 24, or 48 gigabit Ethernet ports. Compared with modular switches that allow line cards or service modules in and out as needed, stack switches are more cost-effective in enterprise campus networks which offer endpoint connectivity and uplink capabilities for users at a price per port. Therefore, for those who has limited switch port or enterprise networks that lack of physical expandability, stack switch is an excellent choice for network expansion.

How to Achieve Network Switch Stack?

From the first generation of of Cisco 3750 series stack switches, the stackable Ethernet switch market has become more mature, so does the switch stacking technology. Like Cisco, other network switch vendors like Dell, Brocade and FS.COM also add their own unique features and functionality to their stack switches, which enhance the virtuous circle of switch stacking technology development.

The typical method for switch stacking is to use stacking cable via stackwise port. Take Cisco 3750 series stack switches for example. Stackwise port lies on the rear-panel. Only approved cables can be used to connect the 3750 stack switches with other similar switches. If not, devices easily get damage. In addition, Cisco offers different connection types for this stack: full bandwidth connection and half bandwidth connection, which provide great flexibility for different application requirements.

stack switch with stackwise-cable

Another way to achieve switch stack is to use the uplink ports. As has mentioned, many switch vendors upgrade the switch stacking technology to improve their competitiveness. Today’s stack switches can be stacked using several types of Ethernet ports such as 10GBASE-T copper port, 10G SFP+ fiber port and 40G QSFP+ port. Here take FS S3800-24F4S stackable managed switch as an example. As shown in the following picture, in the stack, one fiber cable from a 10G SFP+ port on a stack switch is connected to a SFP+ stacking port on the next switch. This process is repeated until all of the devices are connected. And the first stack switch is also connected with the last one to complete the stacking topology.

FS stack switch with SFP+ uplink


Stack switch, no matter uses stack cable or SFP+ stacking/uplink port, provides high bandwidth port density and easy management for network design. But compared with the way of using stack cable, stacking/uplink port is more cost-effective. Besides, using fiber uplink port to stack switch can realize long distance stacking in different areas, which are more popular in today’s network infrastructures.

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