{"id":4116,"date":"2025-05-08T17:33:49","date_gmt":"2025-05-08T17:33:49","guid":{"rendered":"https:\/\/www.it-react.com\/?p=4116"},"modified":"2025-09-19T17:05:19","modified_gmt":"2025-09-19T17:05:19","slug":"esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-4","status":"publish","type":"post","link":"https:\/\/www.it-react.com\/index.php\/2025\/05\/08\/esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-4\/","title":{"rendered":"ESXi Packet Loss Troubleshooting with iPerf3 &amp; pktcap-uw \u2013 Part 4"},"content":{"rendered":"\n<div style=\"border-left: 4px solid #3498db; padding: 10px; background-color: #eef6fc;\">\n  <strong>This article is part of the 5-part series:<\/strong><br>\n  <em>\u201cESXi Packet Loss Troubleshooting with iPerf3 and pktcap-uw\u201d<\/em>\n  <ul style=\"margin-top: 5px; margin-bottom: 5px;\">\n    <li><a class=\"effect1\" href=\"https:\/\/www.it-react.com\/index.php\/2025\/04\/19\/esxi-packet-loss-troubleshooting-with-iperf3-and-pktcap-uw-part-1\/\" target=\"_blank\"><strong>Part 1:<\/strong> Baseline Testing and Setup<\/a><\/li>\n    <li><a class=\"effect1\" href=\"https:\/\/www.it-react.com\/index.php\/2025\/04\/27\/esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-2\/\" target=\"_blank\"><strong>Part 2:<\/strong> Capturing UDP Traffic Under Different CPU Loads<\/a><\/li>\n    <li><a class=\"effect1\" href=\"https:\/\/www.it-react.com\/index.php\/2025\/05\/06\/esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-3\/\" target=\"_blank\"><strong>Part 3:<\/strong> Analyzing Packet Loss with Wireshark<\/a><\/li>\n    <li><u><strong>Part 4:<\/strong> UDP Loss from Link Flapping and Network Instability<\/u> \u2190 You are here <\/li>\n    <li><a class=\"effect1\" href=\"https:\/\/www.it-react.com\/index.php\/2025\/05\/08\/esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-5\/\" target=\"_blank\"><strong>Part 5:<\/strong> Inter-VLAN UDP Loss Caused by Bandwidth Limits<\/a><\/li>\n  <\/ul>\n<\/div>\n\n\n\n<p>While previous scenarios focused on CPU stress and normal transmission conditions, this scenario simulates a more disruptive condition \u2014 a flapping connection. In many real-world environments, intermittent link failures or unstable uplinks can result in seemingly random packet loss, session resets, or erratic application behavior. By intentionally introducing link flaps, we can observe how UDP traffic behaves when connectivity is interrupted and quickly restored.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Lab Setup Recap<\/strong><\/h2>\n\n\n\n<p><strong>Sending VM<\/strong>: 192.168.110.101 (VLAN 110)<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Receiving VM<\/strong>: 192.168.110.103 (VLAN 110)<\/li>\n\n\n\n<li><strong>Link Instability Simulation<\/strong>: Interface flapping (e.g., disconnecting the link between phisycal switches a few times)<\/li>\n\n\n\n<li><strong>Traffic Generator<\/strong>: iPerf3 using UDP, sustained for 300 seconds<\/li>\n<\/ul>\n\n\n\n<figure data-wp-context=\"{&quot;imageId&quot;:&quot;69ebd3204e0a9&quot;}\" data-wp-interactive=\"core\/image\" class=\"wp-block-image size-large wp-lightbox-container\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"485\" data-wp-class--hide=\"state.isContentHidden\" data-wp-class--show=\"state.isContentVisible\" data-wp-init=\"callbacks.setButtonStyles\" data-wp-on-async--click=\"actions.showLightbox\" data-wp-on-async--load=\"callbacks.setButtonStyles\" data-wp-on-async-window--resize=\"callbacks.setButtonStyles\" src=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-1024x485.jpg\" alt=\"\" class=\"wp-image-4120\" srcset=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-1024x485.jpg 1024w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-300x142.jpg 300w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-768x364.jpg 768w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-1536x728.jpg 1536w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/iperf_network_drop-2048x971.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><button\n\t\t\tclass=\"lightbox-trigger\"\n\t\t\ttype=\"button\"\n\t\t\taria-haspopup=\"dialog\"\n\t\t\taria-label=\"Enlarge\"\n\t\t\tdata-wp-init=\"callbacks.initTriggerButton\"\n\t\t\tdata-wp-on-async--click=\"actions.showLightbox\"\n\t\t\tdata-wp-style--right=\"state.imageButtonRight\"\n\t\t\tdata-wp-style--top=\"state.imageButtonTop\"\n\t\t>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"12\" height=\"12\" fill=\"none\" viewBox=\"0 0 12 12\">\n\t\t\t\t<path fill=\"#fff\" d=\"M2 0a2 2 0 0 0-2 2v2h1.5V2a.5.5 0 0 1 .5-.5h2V0H2Zm2 10.5H2a.5.5 0 0 1-.5-.5V8H0v2a2 2 0 0 0 2 2h2v-1.5ZM8 12v-1.5h2a.5.5 0 0 0 .5-.5V8H12v2a2 2 0 0 1-2 2H8Zm2-12a2 2 0 0 1 2 2v2h-1.5V2a.5.5 0 0 0-.5-.5H8V0h2Z\" \/>\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Scenario 3: Packet Loss Due to Flapping Connection<\/strong><\/h2>\n\n\n\n<p><strong>Goal:<\/strong> To simulate and analyze how intermittent network link disruptions affect UDP packet transmission between two VMs on the same subnet.<\/p>\n\n\n\n<p><strong>Method:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Run continuous UDP traffic from sender to receiver at 5 Mbps using iPerf3.<\/li>\n\n\n\n<li>Manually introduce 1\u20133 short connection outages (e.g., disable and re-enable the vmnic or port group or disconnect the link between phisycal switches a few times).<\/li>\n\n\n\n<li>Capture traffic with pktcap-uw and monitor iPerf3 output and Wireshark traces for signs of packet loss or jitter.<\/li>\n<\/ul>\n\n\n\n<p><strong>Expected Outcome:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>UDP packets will be lost during each link-down event.<\/li>\n\n\n\n<li>iPerf3 will show high packet loss and possible jitter spikes.<\/li>\n\n\n\n<li>Wireshark will show time gaps and broken sequence continuity.<\/li>\n\n\n\n<li>No packet retransmission will occur (since it\u2019s UDP).<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step one: Start iPerf3 on Windows VMs<\/strong><\/h3>\n\n\n\n<p>Start iPerf3 server and client on Windows VMs to generate UDP traffic:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>iperf3 -s -B 192.168.110.103 -p 10101 --&gt; Server \niperf3 -c 192.168.110.103 -u -b 5M -l 1400 -t 300 -p 10101 --&gt; Client<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step Two: Start pktcap-uw packet capture<\/strong><\/h3>\n\n\n\n<p>Connect to sending and receiving hosts via SSH, find a location on the datastore to save the pcap files and then start the trace on both switchport and vmnic.<br>For detailed usage of pktcap-uw, refer back to Part 2 where the command syntax and capture options are explained in full.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step three: Simulate Link Flaps<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>While the test is running, simulate short link failures:\n<ul class=\"wp-block-list\">\n<li>On physical switch: disable and re-enable the port, or temporarily unplug the cable<\/li>\n\n\n\n<li>On ESXi host: disable the vmnic, port group, or uplink from the vSwitch settings<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step Four: Analyze iPerf3 and Packet Captures<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>iPerf3<\/strong>: Large packet loss percentages during the flap moments<\/li>\n\n\n\n<li><strong>Wireshark<\/strong>: Delta Time Displayed shows large gaps between packets<\/li>\n\n\n\n<li><strong>pktcap-uw<\/strong>: Transmission continues on sender, but receiver misses bursts of traffic<\/li>\n<\/ul>\n\n\n\n<figure data-wp-context=\"{&quot;imageId&quot;:&quot;69ebd3204e94f&quot;}\" data-wp-interactive=\"core\/image\" class=\"wp-block-image aligncenter size-full is-resized wp-lightbox-container\"><img loading=\"lazy\" decoding=\"async\" width=\"684\" height=\"318\" data-wp-class--hide=\"state.isContentHidden\" data-wp-class--show=\"state.isContentVisible\" data-wp-init=\"callbacks.setButtonStyles\" data-wp-on-async--click=\"actions.showLightbox\" data-wp-on-async--load=\"callbacks.setButtonStyles\" data-wp-on-async-window--resize=\"callbacks.setButtonStyles\" src=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-18.png\" alt=\"\" class=\"wp-image-4141\" style=\"width:684px;height:auto\" srcset=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-18.png 684w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-18-300x139.png 300w\" sizes=\"auto, (max-width: 684px) 100vw, 684px\" \/><button\n\t\t\tclass=\"lightbox-trigger\"\n\t\t\ttype=\"button\"\n\t\t\taria-haspopup=\"dialog\"\n\t\t\taria-label=\"Enlarge\"\n\t\t\tdata-wp-init=\"callbacks.initTriggerButton\"\n\t\t\tdata-wp-on-async--click=\"actions.showLightbox\"\n\t\t\tdata-wp-style--right=\"state.imageButtonRight\"\n\t\t\tdata-wp-style--top=\"state.imageButtonTop\"\n\t\t>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"12\" height=\"12\" fill=\"none\" viewBox=\"0 0 12 12\">\n\t\t\t\t<path fill=\"#fff\" d=\"M2 0a2 2 0 0 0-2 2v2h1.5V2a.5.5 0 0 1 .5-.5h2V0H2Zm2 10.5H2a.5.5 0 0 1-.5-.5V8H0v2a2 2 0 0 0 2 2h2v-1.5ZM8 12v-1.5h2a.5.5 0 0 0 .5-.5V8H12v2a2 2 0 0 1-2 2H8Zm2-12a2 2 0 0 1 2 2v2h-1.5V2a.5.5 0 0 0-.5-.5H8V0h2Z\" \/>\n\t\t\t<\/svg>\n\t\t<\/button><figcaption class=\"wp-element-caption\">iPerf Result<\/figcaption><\/figure>\n\n\n\n<figure data-wp-context=\"{&quot;imageId&quot;:&quot;69ebd3204efe8&quot;}\" data-wp-interactive=\"core\/image\" class=\"wp-block-image aligncenter size-full is-resized wp-lightbox-container\"><img loading=\"lazy\" decoding=\"async\" width=\"676\" height=\"672\" data-wp-class--hide=\"state.isContentHidden\" data-wp-class--show=\"state.isContentVisible\" data-wp-init=\"callbacks.setButtonStyles\" data-wp-on-async--click=\"actions.showLightbox\" data-wp-on-async--load=\"callbacks.setButtonStyles\" data-wp-on-async-window--resize=\"callbacks.setButtonStyles\" src=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-19.png\" alt=\"\" class=\"wp-image-4142\" style=\"width:686px;height:auto\" srcset=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-19.png 676w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-19-300x298.png 300w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-19-150x150.png 150w\" sizes=\"auto, (max-width: 676px) 100vw, 676px\" \/><button\n\t\t\tclass=\"lightbox-trigger\"\n\t\t\ttype=\"button\"\n\t\t\taria-haspopup=\"dialog\"\n\t\t\taria-label=\"Enlarge\"\n\t\t\tdata-wp-init=\"callbacks.initTriggerButton\"\n\t\t\tdata-wp-on-async--click=\"actions.showLightbox\"\n\t\t\tdata-wp-style--right=\"state.imageButtonRight\"\n\t\t\tdata-wp-style--top=\"state.imageButtonTop\"\n\t\t>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"12\" height=\"12\" fill=\"none\" viewBox=\"0 0 12 12\">\n\t\t\t\t<path fill=\"#fff\" d=\"M2 0a2 2 0 0 0-2 2v2h1.5V2a.5.5 0 0 1 .5-.5h2V0H2Zm2 10.5H2a.5.5 0 0 1-.5-.5V8H0v2a2 2 0 0 0 2 2h2v-1.5ZM8 12v-1.5h2a.5.5 0 0 0 .5-.5V8H12v2a2 2 0 0 1-2 2H8Zm2-12a2 2 0 0 1 2 2v2h-1.5V2a.5.5 0 0 0-.5-.5H8V0h2Z\" \/>\n\t\t\t<\/svg>\n\t\t<\/button><figcaption class=\"wp-element-caption\">Wireshark Capture on esxi0 vmnic- I\/O graph showing packet burst<\/figcaption><\/figure>\n\n\n\n<figure data-wp-context=\"{&quot;imageId&quot;:&quot;69ebd3204f7aa&quot;}\" data-wp-interactive=\"core\/image\" class=\"wp-block-image aligncenter size-full is-resized wp-lightbox-container\"><img loading=\"lazy\" decoding=\"async\" width=\"676\" height=\"672\" data-wp-class--hide=\"state.isContentHidden\" data-wp-class--show=\"state.isContentVisible\" data-wp-init=\"callbacks.setButtonStyles\" data-wp-on-async--click=\"actions.showLightbox\" data-wp-on-async--load=\"callbacks.setButtonStyles\" data-wp-on-async-window--resize=\"callbacks.setButtonStyles\" src=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-20.png\" alt=\"\" class=\"wp-image-4143\" style=\"width:692px;height:auto\" srcset=\"https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-20.png 676w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-20-300x298.png 300w, https:\/\/www.it-react.com\/wp-content\/uploads\/2025\/05\/grafik-20-150x150.png 150w\" sizes=\"auto, (max-width: 676px) 100vw, 676px\" \/><button\n\t\t\tclass=\"lightbox-trigger\"\n\t\t\ttype=\"button\"\n\t\t\taria-haspopup=\"dialog\"\n\t\t\taria-label=\"Enlarge\"\n\t\t\tdata-wp-init=\"callbacks.initTriggerButton\"\n\t\t\tdata-wp-on-async--click=\"actions.showLightbox\"\n\t\t\tdata-wp-style--right=\"state.imageButtonRight\"\n\t\t\tdata-wp-style--top=\"state.imageButtonTop\"\n\t\t>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"12\" height=\"12\" fill=\"none\" viewBox=\"0 0 12 12\">\n\t\t\t\t<path fill=\"#fff\" d=\"M2 0a2 2 0 0 0-2 2v2h1.5V2a.5.5 0 0 1 .5-.5h2V0H2Zm2 10.5H2a.5.5 0 0 1-.5-.5V8H0v2a2 2 0 0 0 2 2h2v-1.5ZM8 12v-1.5h2a.5.5 0 0 0 .5-.5V8H12v2a2 2 0 0 1-2 2H8Zm2-12a2 2 0 0 1 2 2v2h-1.5V2a.5.5 0 0 0-.5-.5H8V0h2Z\" \/>\n\t\t\t<\/svg>\n\t\t<\/button><figcaption class=\"wp-element-caption\">Wireshark Capture on esxi2 vmnic- I\/O graph showing packet drop during flap<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Key Findings<\/strong><\/h2>\n\n\n\n<p>This scenario demonstrated that intermittent link disruptions \u2014 even if brief \u2014 result in immediate and unrecoverable UDP packet loss. Unlike TCP, UDP lacks built-in retransmission or state awareness, so each lost packet is gone permanently. Both iPerf3 and Wireshark confirmed that packets were sent from the source VM but never reached the receiver during the flap events. Such disruptions are especially critical for real-time traffic like VoIP, video conferencing, or telemetry, where even momentary drops can degrade quality.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Conclusion<\/strong><\/h2>\n\n\n\n<p>Connection flapping, though often transient, can have a severe impact on UDP-based applications. This test reinforces the importance of stable infrastructure and proper link monitoring. While CPU load and bandwidth constraints can degrade performance gradually, flapping connections introduce sudden, sharp packet loss that is harder to diagnose \u2014 but easy to detect with packet-level tools like pktcap-uw and Wireshark.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>What&#8217;s Next<\/strong><\/h2>\n\n\n\n<p>With the effects of transient disconnections covered, it\u2019s time to shift our attention to the network\u2019s architecture \u2014 specifically inter-VLAN routing and bandwidth shaping. In the next part, we move the receiving VM to a different VLAN and introduce a bandwidth limitation using pfSense to explore how congestion in the routing path affects UDP traffic.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This article is part of the 5-part series: \u201cESXi Packet Loss Troubleshooting with iPerf3 and pktcap-uw\u201d Part 1: Baseline Testing and Setup Part 2: Capturing UDP Traffic Under Different CPU Loads Part 3: Analyzing Packet Loss with Wireshark Part 4: UDP Loss from Link Flapping and Network Instability \u2190 You are here Part 5: Inter-VLAN [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":4232,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_FSMCFIC_featured_image_caption":"Ioan Penu with ChatGPT","_FSMCFIC_featured_image_nocaption":"","_FSMCFIC_featured_image_hide":"","footnotes":""},"categories":[7,62,15],"tags":[],"class_list":["post-4116","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linux","category-network","category-vmware"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>ESXi Packet Loss Troubleshooting with iPerf3 &amp; pktcap-uw \u2013 Part 4 - IT-REACT<\/title>\n<meta name=\"description\" content=\"Learn how link instability and short network outages impact UDP traffic in ESXi. Simulate flapping and capture packet loss with pktcap-uw.\" \/>\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.it-react.com\/index.php\/2025\/05\/08\/esxi-packet-loss-troubleshooting-with-iperf3-pktcap-uw-part-4\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"ESXi Packet Loss Troubleshooting with iPerf3 &amp; pktcap-uw \u2013 Part 4 - IT-REACT\" \/>\n<meta property=\"og:description\" content=\"Learn how link instability and short network outages impact UDP traffic in ESXi. 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