{"id":1115,"date":"2025-08-27T22:20:07","date_gmt":"2025-08-27T22:20:07","guid":{"rendered":"https:\/\/www.cablesandkits.com\/learning-center\/?p=1115"},"modified":"2025-09-10T23:24:05","modified_gmt":"2025-09-10T23:24:05","slug":"qsfp-40g-sr4-vs-qsfp-40g-sr4-s","status":"publish","type":"post","link":"https:\/\/www.cablesandkits.com\/learning-center\/qsfp-40g-sr4-vs-qsfp-40g-sr4-s\/","title":{"rendered":"QSFP-40G-SR4 vs QSFP-40G-SR4-S: Which 40G Transceiver is Right for You?"},"content":{"rendered":"\n<p>In today&#8217;s fast-moving business world, choosing the right network gear can be tough. If you&#8217;re stuck between the QSFP-40G-SR4 and QSFP-40G-SR4-S transceivers, you&#8217;re not alone. Both offer high-speed performance, but knowing their differences is key to boosting your network.<\/p>\n\n\n\n<p>This article breaks down these 40G&nbsp;transceivers, giving you clear and expert advice to make your choice easier. By the end, you&#8217;ll know which transceiver is the best fit for your business needs.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What are 40G Transceivers?<\/h2>\n\n\n\n<p>40G transceivers are optical modules that can transmit and receive data at a rate of 40 gigabits per second. They are designed to work with networking equipment that supports 40G speeds, such as switches,&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/networking\/equipment\/routers\/cat-84\/\">routers<\/a>, and servers. Common types of 40G transceivers include Cisco QSFP-40G-SR4 and Cisco QSFP-40G-SR4-S.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What is the QSFP-40G-SR4?<\/h2>\n\n\n\n<p>The&nbsp;<strong>QSFP-40G-SR4<\/strong>&nbsp;is a Cisco-compatible Quad Small Form-factor Pluggable Plus (QSFP+) optical transceiver module. It is designed to support high-speed 40GBASE-SR4 Ethernet connectivity over short range.<\/p>\n\n\n\n<p>This module operates over a wavelength of 850nm. It is capable of reaching a maximum link distance of 150 meters over OM4&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/single-mode-vs-multimode-fiber\">multimode fiber<\/a>&nbsp;(MMF) or 100 meters over OM3 MMF, making it suitable for short-range data transmission applications.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Specifications of QSFP-40G-SR4:<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Form Factor:<\/strong>\u00a0QSFP+<\/li>\n\n\n\n<li><strong>Max Data Rate:<\/strong>\u00a040 Gbps<\/li>\n\n\n\n<li><strong>Wavelength:<\/strong>\u00a0850nm<\/li>\n\n\n\n<li><strong>Max Cable Distance:<\/strong>\u00a0150m@OM4 \/ 100m@OM3<\/li>\n\n\n\n<li><strong>Connector:<\/strong>\u00a0MTP\/MPO-12 Male<\/li>\n\n\n\n<li><strong>Media:<\/strong>\u00a0MMF<\/li>\n\n\n\n<li><strong>Transmitter Type:<\/strong>\u00a0VCSEL (Vertical Cavity Surface Emitting Laser)<\/li>\n\n\n\n<li><strong>Receiver Type:<\/strong>\u00a0PIN (Positive-Intrinsic-Negative) photodiode<\/li>\n\n\n\n<li><strong>TX Power:<\/strong>\u00a0-7~1dBm<\/li>\n\n\n\n<li><strong>Receiver Sensitivity:<\/strong>\u00a0&lt;-9.5dBm<\/li>\n\n\n\n<li><strong>Power Consumption:<\/strong>\u00a0&lt;1.5W<\/li>\n\n\n\n<li><strong>Bit Error Ratio (BER):<\/strong>\u00a01E-12<\/li>\n\n\n\n<li><strong>Commercial Temperature Range:<\/strong>\u00a00 to 70\u00b0C (32 to 158\u00b0F)<\/li>\n\n\n\n<li><strong>Protocols:<\/strong>\u00a0IEEE 802.3ba, QSFP+ MSA, SFF-8436<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Key Features<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Compatibility:<\/strong>\u00a0Easy to install and replace without interrupting the network, ensuring minimal downtime and maintenance efficiency.<\/li>\n\n\n\n<li><strong>Versatile Applications:<\/strong>\u00a0Ideal for use in data centers, campus networks, and various network interconnections, including switches, routers, NICs, and transport equipment. The\u00a0<a href=\"https:\/\/www.cablesandkits.com\/networking\/equipment\/modules\/cat-83\/\">module<\/a>\u00a0supports breakout to 4x10GBASE-SR, providing flexibility for different network configurations.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">What is the QSFP-40G-SR4-S?<\/h2>\n\n\n\n<p>The&nbsp;<strong>QSFP-40G-SR4-S<\/strong>&nbsp;is a high-performance optical transceiver module designed for short-range 40GBASE-SR4&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/understanding-ethernet-cable-gauge\">Ethernet<\/a>&nbsp;applications. Only compatible with Cisco equipment, this QSFP+ module operates at a wavelength of 850nm and supports data rates up to 41.25Gbps, making it ideal for high-speed data center connectivity.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Specifications QSFP-40G-SR4-S:<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Max Data Rate:<\/strong>\u00a040 Gbps<\/li>\n\n\n\n<li><strong>Wavelength:<\/strong>\u00a0850nm<\/li>\n\n\n\n<li><strong>Max Cable Distance:<\/strong>\u00a0150m@OM4 \/ 100m@OM3<\/li>\n\n\n\n<li><strong>Connector:<\/strong>\u00a0MTP\/MPO-12 Male<\/li>\n\n\n\n<li><strong>Media:<\/strong>\u00a0MMF<\/li>\n\n\n\n<li><strong>Transmitter Type:<\/strong>\u00a0VCSEL<\/li>\n\n\n\n<li><strong>Receiver Type:<\/strong>\u00a0PIN<\/li>\n\n\n\n<li><strong>TX Power:<\/strong>\u00a0-7~1dBm<\/li>\n\n\n\n<li><strong>Receiver Sensitivity:<\/strong>\u00a0&lt;-9.5dBm<\/li>\n\n\n\n<li><strong>Power Consumption:<\/strong>\u00a0&lt;1.5W<\/li>\n\n\n\n<li><strong>Bit Error Ratio (BER):<\/strong>\u00a01E-12<\/li>\n\n\n\n<li><strong>Commercial Temperature Range:<\/strong>\u00a00 to 70\u00b0C (32 to 158\u00b0F)<\/li>\n\n\n\n<li><strong>Protocols:<\/strong>\u00a0IEEE 802.3ba, QSFP+ MSA, SFF-8436<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Key Features<\/h4>\n\n\n\n<p>The 40GBase-SR4-S transceiver offers several key features that make it an excellent choice for enhancing network performance:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Compatibility:<\/strong>\u00a0Compliant with QSFP+ MSA and IEEE 802.3ba standards, it guarantees compatibility with Cisco-Centered networking equipment.<\/li>\n\n\n\n<li><strong>Versatile Applications:<\/strong>\u00a0The 40GBase-SR4-S works perfectly with any equipment that supports the QSFP+ interface and the 40GBASE-SR4 standard. This means you can use it with hardware that follows the same standards, making it flexible and easy to integrate into network setups. It&#8217;s ideal for use in data centers, campus networks, and connecting switches, routers, and\u00a0<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/how-to-choose-a-network-card\">network interface cards<\/a>\u00a0(NICs) with Cisco-centered equipment.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Major Difference between QSFP-40G-SR4 and QSFP-40G-SR4-S<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Connectivity<\/h3>\n\n\n\n<p><strong>Cisco QSFP-40G-SR4-S (S-Class)<\/strong>: The S-Class module does not support 4x10G breakout mode. This limitation means it is designed solely for high-bandwidth 40G&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/fiber-optic-connector-types\">optical links<\/a>&nbsp;without the capability to split the signal into four separate 10G channels. This can be a significant consideration if your network requires interoperability with lower-speed interfaces or the flexibility to segment the 40G link into multiple 10G links for specific applications.<\/p>\n\n\n\n<p>In contrast, the&nbsp;<strong>QSFP-40G-SR4 Cisco module<\/strong>&nbsp;supports&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/qsfp-40gb-transceivers\">4x10G breakout mode<\/a>. This functionality allows the module to interoperate with 10GBASE-SR and SFP-10\/25G-CSR-S (in 10G mode) interfaces, providing the flexibility to divide a 40G link into four individual 10G links. This capability is particularly useful in network environments where a mix of 40G and 10G connections are needed, offering greater adaptability and scalability.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Versatility<\/h3>\n\n\n\n<p>The&nbsp;<strong>Cisco 40GBase-SR4<\/strong>&nbsp;is widely recognized for its compatibility with various high-density, high-performance computing networks, and data centers, making it a versatile choice for large-scale deployments.<\/p>\n\n\n\n<p>On the other hand, the&nbsp;<strong>Cisco 40GBase-SR4-S<\/strong>, while similar in many aspects, may offer slight firmware optimizations or vendor-specific features that can enhance performance in certain Cisco-specific environments, potentially making it more versatile within&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/all-about-cisco-catalyst-9200-series-switches\">Cisco\u2019s ecosystem<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Which Module Should You Buy? Factors to Consider When Making Your Decision<\/h2>\n\n\n\n<p>Choosing the right module depends on specific factors related to your network environment and requirements. Here are some considerations to help you decide between the Cisco QSFP-40G-SR4 and Cisco QSFP-40G-SR4-S:<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Cost Considerations:<\/h3>\n\n\n\n<p>When comparing the 40GBase-SR4 and 40GBase-SR4-S, the QSFP-40G-SR4-S offers a more budget-friendly option. At CablesandKits, new&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/mc\/transceivers\/qsfp-40g-sr4\/fam-217\/fp-11689\/\">QSFP-40G-SR4<\/a>&nbsp;units are priced at $162.99, refurbished Cisco units at $42.99, and Cisco factory-sealed versions at $139.99. In contrast, the Cisco 40G-SR4-S is typically available at a lower cost, making it a more economical choice if you have all 40Gbase modules in the existing setup.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Network Compatibility:<\/h3>\n\n\n\n<p>If you&#8217;re planning to upgrade to 40G modules, choosing between the&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/s-class-transceivers-vs-non-s-class-transceivers\">S-Class or Non-S-Class<\/a>&nbsp;variant of 40GBase-SR4 depends entirely on your existing system.<\/p>\n\n\n\n<p>For a high-bandwidth 40G optical link without the need to split signals into 10G channels, the S-Class 40GBase-SR4-S is perfect. It\u2019s efficient and designed specifically for pure 40G connections.<\/p>\n\n\n\n<p>However, if your network runs on 10GBase and you need flexibility, go with the Non-S-Class Cisco 40GBase-SR4 module. It supports a 4x10G breakout mode, allowing it to interoperate with 10GBASE-SR and SFP-10\/25G-CSR-S interfaces. This lets you split a 40G link into four individual 10G links, ideal for mixed 40G and 10G environments.<\/p>\n\n\n\n<p>Both options are compatible with&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/c\/network-equipment\">Cisco equipment<\/a>&nbsp;and meet the same standards. Check your network&#8217;s specific needs to decide which module is the best fit for you.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Future Proofing:<\/h3>\n\n\n\n<p>When planning for&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/5-factors-for-installing-ethernet-cables\">future network upgrades<\/a>&nbsp;or expansions, choosing a module that offers better performance or additional features can be more beneficial in the long run.<\/p>\n\n\n\n<p>If your organization is growing, consider the Cisco QSFP-40G-SR4 module. It\u2019s versatile, supporting a 4x10G breakout mode that lets you split a 40G link into four 10G links. This flexibility allows for gradual upgrades without needing to overhaul your entire infrastructure. Although these advanced modules might have a higher upfront cost, they often save money over time by reducing the need for frequent upgrades.<\/p>\n\n\n\n<p>Non-specialized (Non-S-Class) modules, like the QSFP-40G-SR4, are adaptable to various Gigabit Ethernet standards. This versatility makes your network more flexible and able to grow with&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/move-your-business-to-a-fiber-connection\">your business<\/a>.<\/p>\n\n\n\n<p>By investing in these future-proof options, you ensure that your network remains robust, efficient, and ready for future demands.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p>In the competitive realm of high-speed networking, choosing the right transceiver is crucial for performance and efficiency. Both the 40G-SR4 and 40G-SR4-S operate at 850nm, support up to 150 meters over OM4 multimode fiber, and offer data rates up to 40Gbps. They comply with QSFP+ MSA and IEEE 802.3ba standards, ensuring compatibility and reliability.<\/p>\n\n\n\n<p>The QSFP-40G-SR4 supports 4x10G breakout mode, making it ideal for environments needing interoperability with 10G interfaces and segmented connections. Its versatility suits dynamic and scalable network designs. The QSFP-40G-SR4-S is designed for straightforward high-bandwidth 40G links without the need for breakout connectivity or&nbsp;<a href=\"https:\/\/www.cablesandkits.com\/learning-center\/difference-between-fcoe-and-fcip\">FCoE<\/a>, offering a cost-effective solution for data centers and enterprise networks prioritizing simplicity and efficiency.<\/p>\n\n\n\n<p>Ultimately, your choice should be guided by cost, specific application requirements, and long-term reliability needs, ensuring you select the module that best aligns with your network\u2019s demands and goals.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Additional Learning Center Resources<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/s-class-transceivers-vs-non-s-class-transceivers\"><strong><u>&#8220;S-Class&#8221; Transceivers vs Non &#8220;S-Class&#8221; Transceivers<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/choosing-the-right-transceiver\"><strong><u>How to Choose the Right Transceiver for Your Network<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/everything-about-fiber-optic-cables-including-om5\"><strong><u>Everything you need to know about fiber optic cables<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/cisco-catalyst-switches-product-guide\"><strong><u>Choosing the right Cisco Catalyst Switches for your network<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/network-security-with-cisco-ise\"><strong><u>Enhancing Network Security with Cisco ISE (Identity Services Engine)<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/all-about-100g-transceivers\"><strong><u>All About 100G Transceivers and Uses in Data Centers<\/u><\/strong><\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.cablesandkits.com\/learning-center\/all-about-cisco-active-optical-cables\"><strong><u>All About Cisco Active Optical Cables<\/u><\/strong><\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>In today&#8217;s fast-moving business world, choosing the right network gear can be tough. If you&#8217;re stuck between the QSFP-40G-SR4 and QSFP-40G-SR4-S transceivers, you&#8217;re not alone. Both offer high-speed performance, but knowing their differences is key to boosting your network. This article breaks down these 40G&nbsp;transceivers, giving you clear and expert advice to make your choice [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":1111,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1115","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-networking-equipment"],"acf":[],"contentshake_article_id":"","yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.8 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>QSFP-40G-SR4 vs QSFP-40G-SR4-S Comparison Guide - Cables and Kits - Learning Center<\/title>\n<meta name=\"description\" content=\"QSFP-40G-SR4 vs QSFP-40G-SR4-S: Compare features, compatibility, and performance of these fiber transceivers.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.cablesandkits.com\/learning-center\/qsfp-40g-sr4-vs-qsfp-40g-sr4-s\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"QSFP-40G-SR4 vs QSFP-40G-SR4-S Comparison Guide - 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