{"id":4048,"date":"2026-05-12T10:20:17","date_gmt":"2026-05-12T10:20:17","guid":{"rendered":"https:\/\/lp.szlogic.cn\/glossary\/remote-direct-memory-access-rdma-data-transfer-speed-latency\/"},"modified":"2026-05-26T03:08:47","modified_gmt":"2026-05-26T03:08:47","slug":"remote-direct-memory-access-rdma-data-transfer-speed-latency","status":"publish","type":"post","link":"https:\/\/lp.szlogic.cn\/ru\/glossary\/remote-direct-memory-access-rdma-data-transfer-speed-latency","title":{"rendered":"What is RDMA? The Ultimate Guide to Remote Direct Memory Access"},"content":{"rendered":"<figure class=\"wp-block-image aligncenter size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1200\" height=\"712\" src=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c.webp\" alt=\"Remote Direct Memory Access (RDMA)\" class=\"wp-image-4046\" srcset=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c.webp 1200w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c-300x178.webp 300w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c-1024x608.webp 1024w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c-768x456.webp 768w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/f5687c7be3774f809d4f115676635f9c-18x12.webp 18w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">In the world of high-performance computing <a target=\"_blank\" rel=\"\" href=\"https:\/\/resources.l-p.com\/glossary\/what-is-hpc-high-performance-computing\"><strong>(HPC)<\/strong><\/a>, data centers, and AI, speed is everything. Every microsecond of latency and every CPU cycle counts. But traditional network protocols like TCP\/IP create a significant bottleneck, forcing CPUs to spend precious time processing network traffic instead of running applications.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is where a revolutionary technology comes into play: <strong>Remote Direct Memory Access (RDMA)<\/strong>. It&#8217;s the powerhouse behind modern, low-latency, high-throughput networks. Let&#8217;s dive into <strong>what RDMA is<\/strong>, why it matters, and how it&#8217;s shaping the future of data-intensive technologies.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; Key Takeaways<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p>RDMA lets computers send data fast without using the CPU or operating system. This makes things quicker and helps more data move at once.<\/p><\/li><li><p>Zero-copy networking is an important part of RDMA. It lets data go straight from one computer\u2019s memory to another. This saves time and does not use much CPU power.<\/p><\/li><li><p>RDMA works well for high-performance computing, AI, and cloud apps. It can move a lot of data quickly and easily.<\/p><\/li><li><p>You need <strong>special hardware<\/strong>, like RDMA network cards, for RDMA to work. Make sure your devices can use RDMA before you start.<\/p><\/li><li><p>Think about RDMA\u2019s good points, like better speed and saving resources, when you choose if it fits your network.<\/p><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; What Exactly is RDMA? The Core Concept<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">At its heart, <strong>RDMA (Remote Direct Memory Access)<\/strong> is a networking technology that allows computers to exchange data directly between their main memories <strong>without involving their operating systems, CPUs, or cache<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Think of it like this:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p style=\"margin: 0px;\"><strong>Traditional Networking:<\/strong> A package (data) must go through the central mail sorting facility (CPU) to be processed, labeled, and then sent out. This takes time and resources.<\/p><\/li><li><p style=\"margin: 0px;\"><strong>RDMA Networking:<\/strong> The package is handed directly from one person&#8217;s hand (memory) to another&#8217;s across the street, with no middlemen. It&#8217;s incredibly fast and efficient.<\/p><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">This &#8220;kernel bypass&#8221; is the magic that eliminates the major overhead of traditional networking.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" ><strong>How Does RDMA Work? The Technical Magic<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">RDMA operates through a dedicated <strong>Network Interface Card (NIC)<\/strong> often called an <strong>RDMA-enabled NIC<\/strong> or <strong>Host Channel Adapter (HCA)<\/strong>. This specialized hardware handles the data transfer operations independently.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The process involves one computer (the <strong>requester<\/strong>) directly reading from or writing to the memory of another computer (the <strong>responder<\/strong>), after a secure connection has been established. All of this is managed by the HCAs on each end, with minimal CPU involvement.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; Why is RDMA a Game-Changer? Key Benefits &amp; Advantages<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Adopting RDMA technology offers profound advantages for performance-hungry environments:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p style=\"margin: 0px;\"><strong>&#x1f525; Extremely Low Latency:<\/strong> By bypassing the CPU and kernel, data transfer delays are drastically reduced.<\/p><\/li><li><p style=\"margin: 0px;\"><strong>&#x26a1; High Throughput:<\/strong> RDMA enables near-wire-speed data transfer, maximizing the bandwidth of your network infrastructure.<\/p><\/li><li><p style=\"margin: 0px;\"><strong>&#x1f4aa; Reduced CPU Overhead:<\/strong> The CPU is freed from network processing tasks, allowing it to dedicate all its power to running applications and services.<\/p><\/li><li><p style=\"margin: 0px;\"><strong>&#x1f680; Higher Efficiency &amp; Scalability:<\/strong> Systems can handle more data and more connections without being bogged down by network protocol processing.<\/p><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; RDMA Transport Protocols: InfiniBand, RoCE, and iWARP<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">RDMA isn&#8217;t just one standard; it can run over different physical networks. Here\u2019s a quick comparison of the three primary transports:<\/p>\n\n\n\n<figure class=\"wp-block-table\">\n<table class=\"has-fixed-layout\">\n<colgroup><col style=\"min-width: 25px;\"\/><col style=\"min-width: 25px;\"\/><col style=\"min-width: 25px;\"\/><col style=\"min-width: 25px;\"\/><\/colgroup><tbody><tr><th colspan=\"1\" rowspan=\"1\"><p><strong>Protocol<\/strong><\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p><strong>Full Name<\/strong><\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p><strong>Network Medium<\/strong><\/p><\/th><th colspan=\"1\" rowspan=\"1\"><p><strong>Key Characteristics<\/strong><\/p><\/th><\/tr><tr><td colspan=\"1\" rowspan=\"1\"><p><strong>InfiniBand<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>\u2014<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Native InfiniBand Fabric<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>&#x2b50; <strong>Native RDMA.<\/strong> Highest performance, lowest latency. Requires specialized InfiniBand switches.<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\"><p><strong>RoCE<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p><strong>RDMA over Converged Ethernet<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Ethernet<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>&#x1f680; <strong>RDMA over Ethernet.<\/strong> Popular choice for modern data centers. Comes in two versions: RoCEv1 (link-layer) and RoCEv2 (routable over IP).<\/p><\/td><\/tr><tr><td colspan=\"1\" rowspan=\"1\"><p><strong>iWARP<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p><strong>Internet Wide-Area RDMA Protocol<\/strong><\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>Ethernet (TCP)<\/p><\/td><td colspan=\"1\" rowspan=\"1\"><p>&#x1f310; <strong>RDMA over TCP\/IP.<\/strong> Designed to work over standard, lossy networks like WANs. Simpler configuration than RoCE but can have higher latency.<\/p><\/td><\/tr><\/tbody>\n<\/table>\n<\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>RoCE<\/strong> (particularly RoCEv2) has become a dominant force in enterprise data centers as it leverages ubiquitous Ethernet infrastructure while delivering near-InfiniBand performance.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; Where is RDMA Used? Real-World Applications<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">RDMA isn&#8217;t just a lab technology; it&#8217;s critical for today&#8217;s most demanding workloads:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><p style=\"margin: 0px;\"><strong>AI and Machine Learning (ML):<\/strong> Training complex models requires moving massive datasets between servers and GPUs at incredible speeds.<\/p><\/li><li><p style=\"margin: 0px;\"><a target=\"_blank\" rel=\"\" href=\"https:\/\/resources.l-p.com\/glossary\/what-is-hpc-high-performance-computing\"><strong>High-Performance Computing (HPC)<\/strong><\/a><strong>:<\/strong> Scientific simulations and modeling rely on fast message passing between compute nodes (e.g., in MPI applications).<\/p><\/li><li><p style=\"margin: 0px;\"><strong>Hyperconverged Infrastructure (HCI) &amp; Storage:<\/strong> Technologies like VMware vSAN, Azure Stack HCI, and <strong>storage solutions<\/strong> use RDMA for ultra-fast storage networking and disaggregated storage.<\/p><\/li><li><p style=\"margin: 0px;\"><strong>Cloud Data Centers:<\/strong> Major providers like Google, AWS, and Microsoft use RDMA to improve efficiency and performance for their internal infrastructure and cloud services.<\/p><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; The Critical Role of High-Speed Optics in RDMA<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large\"><img decoding=\"async\" width=\"1200\" height=\"675\" src=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b.webp\" alt=\"OPTICAL TRANSCEIVER\" class=\"wp-image-4047\" srcset=\"https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b.webp 1200w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b-300x169.webp 300w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b-1024x576.webp 1024w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b-768x432.webp 768w, https:\/\/lp.szlogic.cn\/wp-content\/uploads\/2026\/05\/44d4bbca12234ce3a2bd2246e96cc61b-18x10.webp 18w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">An <strong>RDMA network<\/strong> is only as fast as its slowest component. <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-26044-200-400-800g-transceiver-modules.htm\"><strong>High-speed optical transceivers<\/strong><\/a> are the unsung heroes that physically enable these lightning-fast connections over <a target=\"_blank\" rel=\"\" href=\"https:\/\/resources.l-p.com\/knowledge-center\/fiber-optic-cable-what-it-is-and-how-it-works-explained\"><strong>fiber optic cables<\/strong><\/a>. For an RDMA network to achieve its full potential, especially on 100G, 200G, or 400G links, you need reliable, high-performance optics.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is where a brand like <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-25432-optics-transceivers-sfp-modules.htm\"><strong>LINK-PP<\/strong><\/a> excels. <strong>LINK-PP <\/strong><a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/store-25432-optics-transceivers-sfp-modules.htm\"><strong>optical transceivers<\/strong><\/a> are engineered for maximum performance and compatibility, ensuring that your RDMA-enabled network operates at peak efficiency without bottlenecks.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a 400G RoCE deployment, a module like the <strong>LINK-PP 400G-ZR4+<\/strong> coherent pluggable transceiver is an excellent choice for long-haul interconnects, providing the reach and signal integrity necessary for a robust infrastructure.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; Conclusion: RDMA is the Future of Data Center Networking<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>RDMA<\/strong> has evolved from a niche technology to a fundamental pillar of modern data center design. Its ability to provide <strong>low-latency networking<\/strong>, <strong>high bandwidth<\/strong>, and <strong>exceptional CPU efficiency<\/strong> makes it indispensable for AI, HPC, and large-scale storage environments.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">To build a true end-to-end high-performance network, pairing RDMA-enabled NICs and switches with top-tier optical components from experts like <a target=\"_blank\" rel=\"\" href=\"https:\/\/www.l-p.com\/page\/aboutus.htm\"><strong>LINK-PP<\/strong><\/a> is not just an option\u2014it&#8217;s a necessity.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; FAQ<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" >What is RDMA used for?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">You use RDMA to move data quickly between computers. It helps with <a target=\"_blank\" rel=\"\" href=\"https:\/\/resources.l-p.com\/knowledge-center\/what-is-cloud-computing-access-servers-storage-apps-online\">cloud computing<\/a>, AI, and storage networks. You get faster speeds and lower wait times than with older network methods.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >What hardware do you need for RDMA?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">You need RDMA-capable network cards and special switches. Regular network cards do not support RDMA. Make sure your servers and network devices work with RDMA before you upgrade.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >What makes RDMA different from regular networking?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">RDMA lets you send data straight from one computer\u2019s memory to another. You skip the CPU and operating system. Regular networking uses more steps and takes longer.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >What is the internet wide area RDMA protocol?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The internet wide area RDMA protocol allows you to use RDMA over long distances. You can connect computers in different locations and still get fast data movement.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" >What are the main benefits of RDMA?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">You get high speed, low latency, and less CPU usage. RDMA helps your systems run more jobs at the same time. Your network works better for big data and real-time tasks.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" ><strong>&#x1f4a1; See Also<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><a target=\"_blank\" href=\"https:\/\/resources.l-p.com\/knowledge-center\/essential-role-roadm-cloud-networks\">The Importance of ROADM in Modern Cloud Networking<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a target=\"_blank\" href=\"https:\/\/resources.l-p.com\/glossary\/ddm-dom-in-optical-transceivers\">The Significance of Digital Monitoring in Optical Transceivers<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a target=\"_blank\" href=\"https:\/\/resources.l-p.com\/glossary\/wdm-optical-transceiver-module-applications\">Exploring WDM Technology and Its Uses in Networking<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a target=\"_blank\" href=\"https:\/\/resources.l-p.com\/knowledge-center\/qsfp-dd-optical-transceivers-faster-connections\">QSFP-DD Transceivers: Enabling High-Speed Data Connections<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>Remote Direct Memory Access boosts data transfer speed, lowers latency, and reduces CPU usage for high-performance computing and cloud applications.<\/p>","protected":false},"author":1,"featured_media":4046,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[27],"tags":[26],"class_list":["post-4048","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-glossary","tag-optics-transceivers"],"blocksy_meta":[],"acf":[],"_links":{"self":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/4048","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/comments?post=4048"}],"version-history":[{"count":2,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/4048\/revisions"}],"predecessor-version":[{"id":7925,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/posts\/4048\/revisions\/7925"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/media\/4046"}],"wp:attachment":[{"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/media?parent=4048"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/categories?post=4048"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lp.szlogic.cn\/ru\/wp-json\/wp\/v2\/tags?post=4048"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}