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[1. What are Fiber Channel Optical Modules?]

Fiber Channel optical modules are essential components in Fiber Channel infrastructure, while Ethernet optical modules, in combination with Ethernet switches, are common configurations in Ethernet networks.


1.   What are Fiber Channel Optical Modules?
Fiber Channel (FC) is a high-speed network data transmission protocol that enables lossless, ordered transmission of raw data. It is primarily used for data transmission in data centers, computer servers, switches, and storage networks.

Fiber Channel (FC) optical modules adhere to the FC protocol and serve as interfaces between Fiber Channel systems, as well as interfaces between Fiber Channel storage network devices. They are primarily used for Fiber Channel storage network links in data centers. FC optical modules are characterized by their compact size and low power consumption, meeting the requirements for fast, lossless transmission of large amounts of information. FC optical modules typically operate at Fiber Channel speeds ranging from 1Gbps to 128Gbps, with expectations to reach 256Gbps and 512Gbps. Common form factors include SFP, SFP+, SFP28, SFP56, and QSFP28.



2.   What are Ethernet Optical Modules?
Ethernet, based on the IEEE 802.3 standard, is a widely used network protocol for local area networks (LANs). Due to its backward compatibility, higher bandwidth, and longer link distances, Ethernet is gradually replacing traditional wired LAN technologies like Token Ring, FDDI, and ARCNET.

Ethernet optical modules adhere to Ethernet protocols and are primarily used in LANs to connect network hardware devices through the transmission and reception of data signals. Common form factors for Ethernet optical modules include 1G SFP, 10G SFP+, 25G SFP28, 40G QSFP+, 50G QSFP28, 100G QSFP28, 400G QSFP-DD, and various Ethernet optical module transmission speeds ranging from 1G to 400G. These modules include conventional optical modules as well as WDM and BiDi optical modules.


3.   What Are the Differences Between FC and Ethernet Optical Modules?

Protocol and Security
FC optical modules operate according to the Fiber Channel protocol and do not adhere to the OSI model's layered approach. In contrast, Ethernet optical modules follow the IEEE 802.3 standard and implement packet-based physical communication within LANs. Ethernet is a data link layer protocol within the TCP/IP stack and adheres to the OSI model.

Storage Area Networks (SANs) are isolated from external networks, reducing the risk of attacks and data leaks, making FC optical modules a more secure choice for SAN applications. In contrast, Ethernet modules operating under the TCP/IP protocol have a series of security vulnerabilities. Since end-to-end management occurs within the network, the entire system is more susceptible to attacks.


Reliability
The protocol and different transmission modes lead to differences in transmission reliability. Compared to Ethernet, Fiber Channel offers superior reliability due to its lossless characteristics. Fiber Channel has a long history of use in storage networks because of this outstanding performance. Ethernet modules do not have the ordered, lossless transmission characteristics of Fiber Channel modules. Additionally, SANs often use Fiber Channel, while Ethernet is suitable for NAS systems. FC modules are designed for users who require high-speed, low-latency block-level storage access. If users need file-level storage access, Ethernet modules are preferred.


Transmission Speed
FC and Ethernet modules have different transmission speed ranges. Specifically, FC modules currently support speeds ranging from 1Gbps to 32Gbps, while Ethernet modules can handle a wider range of transmission speeds, including 10/100/1000Mbps, 10Gbps, 25Gbps, 50Gbps, 40Gbps, 100Gbps, and 400Gbps.

Furthermore, each generation of FC modules typically doubles the speed, from 1Gbps to 32Gbps. Clearly, Ethernet modules have made more significant improvements in throughput, with the latest 400G Ethernet QSFP-DD modules providing nearly 400 times the capacity of initial 1G SFP modules. Ethernet optical modules are better suited to meet the increasing demand for high bandwidth.


Application Areas
The differences between Fiber Channel and Ethernet optical modules also extend to their application areas. Fiber Channel is one of the best ways to transfer large volumes of data between servers and storage devices, making it a preferred choice for Fiber Channel, storage networks, and Ethernet applications. Fiber Channel communication can run on Ethernet through Fiber Channel over Ethernet (FCoE) protocols. FC modules have long been used in large enterprises and data centers.

Ethernet optical modules are typically used in LANs and, at times, in wide area networks. Unlike FC modules, Ethernet modules are versatile and adaptable to various environments, catering to users' bandwidth needs. They are used in a wide range of settings, from small offices to large-scale data centers.


Equipment Compatibility
Maintaining a stable connection between optical modules and switches is crucial for implementing the aforementioned application scenarios. In general, FC modules are installed on FC switches, while Ethernet modules are matched with Ethernet switches, and they are not typically mixed.

Traditional Fiber Channel networks consist of FC switches and Fiber Channel Host Bus Adapters (HBAs) and are a primary choice for SANs. FC switches connect storage to the SAN, while Fiber Channel HBAs connect switches to servers. Ethernet network switches offer diversity in terms of stacking, port count, and transmission rates. When the latest 400G Ethernet optical modules are installed on 400G network switches, it is possible to achieve a 400G network.



4.   Conclusion
Fiber Channel has gained importance in large enterprises and data centers, giving FC optical modules significant significance. Ethernet, with its unique advantages in running various storage and network protocols, has led to the widespread use of Ethernet optical modules. In general, FC and Ethernet optical modules have differences and cater to relatively fixed users and specific network deployments.

As is well known, SFP+ optical transceiver modules are widely used in 10G Ethernet due to their advantages of small size, low cost, and high density. They are currently the most common 10G optical modules in data centers and enterprise campuses. Now, let's take a look at the types of 10G SFP+ optical modules and what are their differences.

The 10G SFP+ series optical modules include SR, LRM, LR, ER, ZR, BIDI, CWDM, DWDM, and 10G electrical port modules. Their interface types are all LC duplex, and they comply with IEEE802.3ae, SFF-8472, and SFF-8431 standards. Here are the specific details of these optical modules:


1.   10G SFP+ SR Optical Transceiver Module

10GBase-SR is one of the Ethernet specifications, and the 10G SFP+ SR optical module complies with this standard. "SR" in the module's name stands for Short Range, meaning it can transmit distances of up to 300m when used with multimode fiber. Additionally, the 10G SFP+ SR optical module has a wavelength of 850nm and offers advantages such as low cost, low power consumption, small form factor, and high density.


2.   10G SFP+ LRM Optical Transceiver Module

The 10G SFP+ LRM optical module complies with the 10GBase-LRM Ethernet standard, where "LRM" stands for Long Reach Multimode. It can be used with OM1, OM2, and OM3 multimode fiber and is primarily used in FDDI networks and 10G data communication. It also fully complies with MSA SFF-8431 standards, offering low power consumption and excellent EMI performance. An upgraded version of the 10G SFP+ LRM optical module is the SFP-10G-LRM2, with a transmission distance of up to 2km, commonly used in local area network connections.


3.   10G SFP+ LR Optical Transceiver Module

The 10G SFP+ LR optical module complies with the 10GBase-LR Ethernet standard, with "LR" standing for Long Range. It can transmit up to 10km (and even up to 25km in some cases) over single-mode fiber, offering advantages such as compact size, low power consumption, and long transmission distance.


4.   10G SFP+ ER Optical Transceiver Module
The 10G SFP+ ER optical module complies with the 10GBase-ER Ethernet standard, with "ER" standing for Extended Range. It operates at a wavelength of 1550nm and can transmit distances of up to 40km when used with single-mode fiber. It is a cost-effective option for long-distance applications and is highly favored in data centers and enterprise campuses.


5.   10G SFP+ ZR Optical Transceiver Module

The 10G SFP+ ZR optical module complies with the 10GBase-ZR Ethernet standard, which is a Cisco proprietary specification. "ZR" in the module's name stands for Ze best Range, indicating that it has an extremely long transmission distance, up to 80km when used with single-mode fiber. Therefore, this optical module finds wide-ranging applications.


6.   10G SFP+ BIDI Optical Transceiver Module

BIDI optical modules are single-fiber bidirectional optical modules available in both SFP and SFP+ form factors. The key difference is that BIDI SFP+ modules have a rate of 10G, while BIDI SFP modules support either 100M or 1G rates. BIDI SFP+ modules use WDM technology and have two fiber connectors, requiring the use of pairs to ensure proper operation. However, these modules have the benefit of reducing the amount of fiber used in network deployment, significantly lowering deployment costs.


7.   10G SFP+ CWDM Optical Transceiver Module

The 10G SFP+ CWDM optical module is a coarse wavelength division multiplexing (CWDM) optical module typically used with single-mode fiber. These modules save fiber resources by using CWDM technology, significantly enhancing network flexibility, economy, and reliability. Additionally, they have very low power consumption, approximately 12.5% of the power consumption of 10G SFP+ DWDM optical modules.


8.   10G SFP+ DWDM Optical Transceiver Module

The 10G SFP+ DWDM optical module is a high-speed, high-capacity dense wavelength division multiplexing (DWDM) optical module, typically used with single-mode fiber. It can transmit distances of up to 80km and is suitable for long-distance data transmission. These modules can meet the demands of ultra-high capacity and long-distance transmission, providing stable support for multi-service operations and future network upgrades and expansion. They also support various networking modes, including wavelength scheduling between nodes, and offer advantages such as easy capacity expansion, flexible service access, high bandwidth utilization, and high reliability.


9.   10G Electrical Port Transceiver Module

The 10G electrical port module is an optoelectronic conversion module with an SFP+ form factor, featuring an RJ45 interface. It is typically used with Category 6 or 7 network patch cables. These modules do not support DOM (Digital Optical Monitoring) functionality and have a transmission distance of 30m, making their application less widespread due to the limited range.

Due to its advantages such as high transmission quality, small size, and light weight, optical fiber communication has completely replaced cable communication. Optical transcriver modules, as an essential component of optical fiber communication, play a crucial role in converting electro-optical signals, transforming the electrical signals of network equipment into optical signals, thus allowing data to be transmitted through Optical fibers. In the following, X-krama will introduce the classification of optical transceiver modules.

Nowadays, optical transceiver modules can be categorized into several main types:



1. Fiber Channel (FC) Optical Transceiver Modules

Fiber Channel (FC) is a high-speed network data transmission protocol that can transmit raw data in an orderly and lossless manner. It is mainly used for data transmission in data centers, computer servers, switches, and storage networks.

Fiber Channel (FC) optical transceiver modules follow the FC protocol and serve as interfaces between optical fiber channel systems and as interfaces between optical storage network devices. They are primarily used in optical fiber channel storage network links in data centers. FC optical modules are characterized by their small size and low power consumption, meeting the demands for fast and lossless transmission of a large amount of information. FC optical modules typically operate at optical fiber channel speeds of 1Gbps to 128Gbps (1Gbps / 2Gbps / 4Gbps / 8Gbps / 16Gbps / 32Gbps / 128Gbps) and are expected to reach 256Gbps and 512Gbps. Common form factors include SFP, SFP+, SFP28, SFP56, and QSFP28.

Storage Area Networks (SAN) are isolated from the external environment, reducing the risk of storage network attacks and data leakage. Therefore, using FC optical modules in storage networks is considered a more secure choice.



2. Dual-Fiber Optical Transceiver Modules

Dual-fiber optical modules are currently available in various transmission rates, such as 1.25Gbps, 10Gbps, 25Gbps,  40Gbps,  56Gbps, 100Gbps, and 400Gbps. Depending on the type of optical fiber used for transmission, they can be divided into multi-mode optical modules and single-mode optical modules. Multi-mode optical modules have shorter transmission distances, with a primary wavelength of 850nm, and they are typically used with multi-mode fiber (OM1 / OM2 / OM3 / OM4 / OM5). The interface types for multi-mode optical modules are LC and MPO. Single-mode optical modules are used for longer-distance transmission, with primary wavelengths of 1310nm, 1490nm, and 1550nm, and they are typically used with single-mode fiber OS2. The main interface types for single-mode optical modules are LC and SC.

Common packaging types for dual-fiber optical modules include SFP for 1.25G, SFP+ for 10G (transmission up to 100km), XFP for 10G (transmission up to 100km), SFP28 for 25G (transmission up to 40km), QSFP+ for 40G (transmission up to 40km), and QSFP28 for 100G (transmission up to 40km).



3. Bidirectional single-fiber (BIDI) Optical Transceiver Modules

BIDI optical transceiver modules are available in various transmission rates, such as 1.25Gbps, 10Gbps, 25Gbps, and 40Gbps. For example, a 1.25G SFP BIDI optical module can transmit up to 160km, a 10G SFP+ BIDI optical module can transmit up to 80km, a 10G XFP BIDI single fiber optical module can transmit up to 100km, a 25G SFP28 BIDI optical module can transmit up to 40km, and a 40G QSFP+ BIDI optical module can transmit up to 150m.



4. CWDM (Coarse Wave Division Multiplexing) Optical Transceiver Modules

CWDM optical transceiver modules have a center wavelength range of 1270nm to 1610nm with 20nm spacing between channels. There are 18 channels to choose from, typically in the 1470-1610nm range. Common transmission distances are 40KM, 80KM, and 120KM. CWDM optical modules support various transmission rates, including 155M CWDM,  1.25G CWDM,  2.5G CWDM and 10G CWDM, corresponding to SFP, SFP+, and XFP form factors.



5. DWDM (Dense Wave Division Multiplexing) Optical Transceiver Modules

DWDM optical transceiver modules operate in the C-band (C17-C61 channels) with wavelengths between 1563.86nm and 1528.77nm, 0.8nm channel spacing, and 45 channels to choose from. Common transmission distances are 40KM and 80KM. DWDM optical modules support various transmission rates, including 155M DWDM SFP,  1.25G DWDM,  2.5G DWDM and 10G DWDM corresponding to SFP, SFP+, and XFP form factors.