{"id":15835,"date":"2025-09-15T06:09:20","date_gmt":"2025-09-15T06:09:20","guid":{"rendered":"https:\/\/www.kaashivinfotech.com\/blog\/?p=15835"},"modified":"2025-09-15T06:09:20","modified_gmt":"2025-09-15T06:09:20","slug":"what-is-switched-port-analyzer","status":"publish","type":"post","link":"https:\/\/www.kaashivinfotech.com\/blog\/what-is-switched-port-analyzer\/","title":{"rendered":"Switched Port Analyzer (SPAN) Made Simple: 7 Things You Can\u2019t Miss"},"content":{"rendered":"<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1n_\" data-state=\"closed\">Assuming you have ever worked in <a href=\"https:\/\/www.wikitechy.com\/category\/networking\/\" target=\"_blank\" rel=\"noopener\">networking<\/a> (or even been allowed to peep into the obscure realm of packets flying across wires), you must have heard of Switched Port Analyzer (SPAN).<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1o_\" data-state=\"closed\">There is something I want to tell you&#8211;I initially heard of it and believed that it is some complicated instrument, which only large technological corporations apply.<\/span> But the truth? <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1p_\" data-state=\"closed\">It is a secret weapon that makes living that much easier upon possession.<\/span><\/p>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1q_\" data-state=\"closed\">At the very beginning&#8211;let us clear one point out.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1r_\" data-state=\"closed\">Switched Port Analyzer (SPAN) is everything about the monitoring of the network traffic without any interference with it.<\/span> That\u2019s the beauty of it. <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1s_\" data-state=\"closed\">Imagine it is as though you sit on the fringe of a busy road, and you see cars passing, and you never get into the traffic.<\/span><\/p>\n<h2><strong><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_1v_\" data-state=\"closed\">What is Switched Port Analyzer (SPAN)?<\/span> (Simple Explanation)<\/strong><\/h2>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"aligncenter wp-image-15840 \" src=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/span-switch-port-analyzer.webp\" alt=\"\" width=\"561\" height=\"261\" srcset=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/span-switch-port-analyzer.webp 628w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/span-switch-port-analyzer-300x139.webp 300w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/span-switch-port-analyzer-380x177.webp 380w\" sizes=\"(max-width: 561px) 100vw, 561px\" \/><\/p>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_20_\" data-state=\"closed\">Okay, I will make it as simple as possible.<\/span><\/p>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_21_\" data-state=\"closed\">A Switched Port Analyzer (SPAN) is a switch configuration option within switches (such as Cisco switches) which duplicates the traffic on a switch port to another switch port where a monitoring tool (such as Wireshark) is attached.<\/span><\/p>\n<ul>\n<li data-start=\"1956\" data-end=\"1990\">\n<p data-start=\"1958\" data-end=\"1990\">Port A = Where traffic happens<\/p>\n<\/li>\n<li data-start=\"1991\" data-end=\"2034\">\n<p data-start=\"1993\" data-end=\"2034\">Port B = Where you \u201cmirror\u201d the traffic<\/p>\n<\/li>\n<li data-start=\"2035\" data-end=\"2111\">\n<p data-start=\"2037\" data-end=\"2111\">Monitoring Tool = The detective\u00a0analyzing what\u2019s really happening<\/p>\n<\/li>\n<\/ul>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_24_\" data-state=\"closed\">you can actually visualise the traffic instead of making guesses about what has caused your network to become slow, or what is causing packets to drop.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_25_\" data-state=\"closed\">And believe me there is nothing like viewing the problem with your own eyes.<\/span><\/p>\n<h2><strong>Why Do We Use Switched Port Analyzer (SPAN)?<\/strong><\/h2>\n<p>When I was a beginner, I remember struggling with unexplained network lags. One day, my mentor said, <em data-start=\"2458\" data-end=\"2498\">\u201cPlug into SPAN and see for yourself.\u201d<\/em> That was a turning point for me.<\/p>\n<p>Here\u2019s why <strong data-start=\"2546\" data-end=\"2572\">switched port analyzer<\/strong> is such a lifesaver:<\/p>\n<ul>\n<li><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2d_\" data-state=\"closed\"><strong>Troubleshooting<\/strong> &#8211; Indication of strange traffic bursts or packet loss.<\/span><\/li>\n<li><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2e_\" data-state=\"closed\"><strong>Security<\/strong> -Identifying malicious packets, sniffers, or even a DoS attack.<\/span><\/li>\n<li><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2f_\" data-state=\"closed\"><strong>Performance Monitoring<\/strong>&#8211; Monitoring latency and jitter of voice\/video calls.<\/span><\/li>\n<li><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2g_\" data-state=\"closed\"><strong>Compliance<\/strong> Some businesses scan packets to audit regulations.<\/span><\/li>\n<\/ul>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2h_\" data-state=\"closed\">It is a network CCTV camera.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2i_\" data-state=\"closed\">You do not feel the traffic but you get to see everything.<\/span><\/p>\n<h2><strong>Types of Switched Port Analyzer (SPAN)<\/strong><\/h2>\n<p><img decoding=\"async\" class=\"aligncenter wp-image-15841 size-full\" src=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span.webp\" alt=\"\" width=\"922\" height=\"372\" srcset=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span.webp 922w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span-300x121.webp 300w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span-768x310.webp 768w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span-380x153.webp 380w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/types_of_span-800x323.webp 800w\" sizes=\"(max-width: 922px) 100vw, 922px\" \/><\/p>\n<p data-start=\"3072\" data-end=\"3142\">Not all SPAN setups are created equal. Here\u2019s what I\u2019ve worked with:<\/p>\n<ol data-start=\"3144\" data-end=\"3524\">\n<li data-start=\"3144\" data-end=\"3267\">\n<p data-start=\"3147\" data-end=\"3267\"><strong data-start=\"3147\" data-end=\"3161\">Local SPAN<\/strong> \u2013 The simplest one. You copy traffic from one port\/VLAN and send it to another port on the same switch.<\/p>\n<\/li>\n<li data-start=\"3268\" data-end=\"3392\">\n<p data-start=\"3271\" data-end=\"3392\"><strong data-start=\"3271\" data-end=\"3294\">RSPAN (Remote SPAN)<\/strong> \u2013 This one is cool. You can mirror traffic <strong data-start=\"3338\" data-end=\"3366\">across multiple switches<\/strong> using a dedicated VLAN.<\/p>\n<\/li>\n<li data-start=\"3393\" data-end=\"3524\">\n<p data-start=\"3396\" data-end=\"3524\"><strong data-start=\"3396\" data-end=\"3433\">ERSPAN (Encapsulated Remote SPAN)<\/strong> \u2013 Fancy stuff. It even sends mirrored traffic over Layer 3 networks (using GRE tunnels).<\/p>\n<\/li>\n<\/ol>\n<p data-start=\"3526\" data-end=\"3686\">\ud83d\udc49 Here\u2019s a <a href=\"https:\/\/www.cisco.com\/c\/en\/us\/support\/docs\/switches\/catalyst-6500-series-switches\/10570-41.html\" target=\"_blank\" rel=\"noopener\">Cisco guide<\/a> if you want the official deep dive.<\/p>\n<h2 data-start=\"3526\" data-end=\"3686\"><strong>Live-life Application of Switched Port Analyzer<\/strong><\/h2>\n<p>I\u2019ll never forget this one. <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_2v_\" data-state=\"closed\">Our group used to receive complaints that VoIP calls were interrupted periodically.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_30_\" data-state=\"closed\">Initially, the ISP was blamed by all, (because, you know we all do).<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_31_\" data-state=\"closed\">However, on applying our switched port analyzer in order to reflect the traffic, guess what?<\/span><\/p>\n<p>We found out that one of the users was going through HD YouTube videos twenty-four-seven, sucking up bandwidth.<\/p>\n<p><img decoding=\"async\" class=\"aligncenter wp-image-15842 \" src=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp.webp\" alt=\"\" width=\"393\" height=\"246\" srcset=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp.webp 1280w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-300x188.webp 300w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-1024x640.webp 1024w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-768x480.webp 768w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-380x238.webp 380w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-800x500.webp 800w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/isp-1160x725.webp 1160w\" sizes=\"(max-width: 393px) 100vw, 393px\" \/><\/p>\n<div class=\"whitespace-pre-line p-2 sm:p-1 min-h-[80px]  max-w-full overflow-x-auto\"><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_33_\" data-state=\"closed\">We did not need to replace routers or contact the ISP at all, but fixed it through the application of QoS rules.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_34_\" data-state=\"closed\">That is the strength of SPAN, you have not speculations, but facts.<\/span><\/div>\n<div>\n<h2 data-start=\"4242\" data-end=\"4288\">Pros and Cons of Switched Port Analyzer<\/h2>\n<p data-start=\"4290\" data-end=\"4349\">Like any tool, SPAN isn\u2019t perfect. Here\u2019s my honest take:<\/p>\n<p data-start=\"4351\" data-end=\"4363\">\u2705 <strong data-start=\"4353\" data-end=\"4361\">Pros<\/strong><\/p>\n<ul data-start=\"4364\" data-end=\"4555\">\n<li data-start=\"4364\" data-end=\"4407\">\n<p data-start=\"4366\" data-end=\"4407\">Easy to set up (especially Local SPAN).<\/p>\n<\/li>\n<li data-start=\"4408\" data-end=\"4444\">\n<p data-start=\"4410\" data-end=\"4444\">Zero impact on original traffic.<\/p>\n<\/li>\n<li data-start=\"4445\" data-end=\"4496\">\n<p data-start=\"4447\" data-end=\"4496\">Great for Wireshark, IDS\/IPS tools, or logging.<\/p>\n<\/li>\n<li data-start=\"4497\" data-end=\"4555\">\n<p data-start=\"4499\" data-end=\"4555\">No need for extra hardware if your switch supports it.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"4557\" data-end=\"4569\">\u274c <strong data-start=\"4559\" data-end=\"4567\">Cons<\/strong><\/p>\n<ul data-start=\"4570\" data-end=\"4739\">\n<li data-start=\"4570\" data-end=\"4605\">\n<p data-start=\"4572\" data-end=\"4605\">Can drop packets if overloaded.<\/p>\n<\/li>\n<li data-start=\"4606\" data-end=\"4661\">\n<p data-start=\"4608\" data-end=\"4661\">Only \u201ccopies\u201d traffic\u2014it doesn\u2019t analyze by itself.<\/p>\n<\/li>\n<li data-start=\"4662\" data-end=\"4739\">\n<p data-start=\"4664\" data-end=\"4739\">On some switches, enabling too many SPAN sessions can affect performance.<\/p>\n<\/li>\n<\/ul>\n<p data-start=\"4741\" data-end=\"4819\">So yeah, <strong data-start=\"4750\" data-end=\"4776\">switched port analyzer<\/strong> is awesome\u2014but don\u2019t rely on it blindly.<\/p>\n<h2 data-start=\"4741\" data-end=\"4819\"><strong>Tools You Can Use With SPAN<\/strong><\/h2>\n<p data-start=\"4863\" data-end=\"4971\">SPAN by itself is just a \u201cmirror.\u201d To get real value, you need tools. My personal toolkit looks like this:<\/p>\n<ul data-start=\"4973\" data-end=\"5150\">\n<li data-start=\"4973\" data-end=\"5016\">\n<p data-start=\"4975\" data-end=\"5016\"><strong data-start=\"4975\" data-end=\"4988\">Wireshark<\/strong>\u00a0 (packet sniffing king)<\/p>\n<\/li>\n<li data-start=\"5017\" data-end=\"5057\">\n<p data-start=\"5019\" data-end=\"5057\"><strong data-start=\"5019\" data-end=\"5030\">tcpdump<\/strong> (lightweight CLI option)<\/p>\n<\/li>\n<li data-start=\"5058\" data-end=\"5103\">\n<p data-start=\"5060\" data-end=\"5103\"><strong data-start=\"5060\" data-end=\"5078\">Snort\/Suricata<\/strong> (security-focused IDS)<\/p>\n<\/li>\n<li data-start=\"5104\" data-end=\"5150\">\n<p data-start=\"5106\" data-end=\"5150\"><strong data-start=\"5106\" data-end=\"5148\">SolarWinds Network Performance Monitor<\/strong><\/p>\n<\/li>\n<\/ul>\n<p data-start=\"5152\" data-end=\"5222\">Pair these with a <strong data-start=\"5170\" data-end=\"5196\">switched port analyzer<\/strong> and you\u2019re unstoppable.<\/p>\n<p data-start=\"5152\" data-end=\"5222\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-15844 size-full\" src=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/wireshark.webp\" alt=\"\" width=\"598\" height=\"336\" srcset=\"https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/wireshark.webp 598w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/wireshark-300x169.webp 300w, https:\/\/www.kaashivinfotech.com\/blog\/wp-content\/uploads\/2025\/09\/wireshark-380x214.webp 380w\" sizes=\"(max-width: 598px) 100vw, 598px\" \/><\/p>\n<h2 data-start=\"5152\" data-end=\"5222\">My Honest Opinion: Should You Learn Switched Port Analyzer in 2025?<\/h2>\n<p>Absolutely YES. <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_3u_\" data-state=\"closed\">I am talking about networks, people, networks are not going to get simpler.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_3v_\" data-state=\"closed\">Cloud, IoT, AI devices &#8211; all dependent on the traffic flow.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_40_\" data-state=\"closed\">Unless you know how to peep inside your traffic, you will be clueless in troubled-shooting.<\/span><\/p>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_41_\" data-state=\"closed\">Having switched port analysis knowledge does not only makes you appear intelligent in front of a group of people or other teammates; it saves time (and at times days) of frustration.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_42_\" data-state=\"closed\">And engineers who are fast at problem solving are loved by employers.<\/span><\/p>\n<h2><strong>Final Thoughts<\/strong><\/h2>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_46_\" data-state=\"closed\">In conclusion, your networking superpower is a switched port analyzer (SPAN).<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_47_\" data-state=\"closed\">Being either a student, a sysadmin, or a person who has their knees in the cybersecurity, you will be glad you learned it.<\/span><\/p>\n<p><span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_48_\" data-state=\"closed\">The following time your boss will tell you, Why is the network slow?&#8211;you will not panic.<\/span> <span aria-haspopup=\"dialog\" aria-expanded=\"false\" aria-controls=\"radix-_r_49_\" data-state=\"closed\">You will plug in SPAN, traffic-capture and with all the confidence say, Here is the problem.<\/span><\/p>\n<p>Want to learn <a href=\"https:\/\/www.kaashivinfotech.com\/networking-training-in-chennai\/\">Networking Course<\/a>, <a href=\"https:\/\/www.kaashivinfotech.com\/cyber-security-course-in-chennai-2\/\">Cyber Security Course<\/a>, <a href=\"https:\/\/www.kaashivinfotech.com\/cloud-computing-course-in-chennai\/\">Cloud Computing Course<\/a> ?, visit our website <a href=\"https:\/\/www.kaashivinfotech.com\/\">www.kaashivinfotech.com<\/a>.<\/p>\n<h2>Related Reads:<\/h2>\n<ul>\n<li>\n<p class=\"entry-title\"><a href=\"https:\/\/www.kaashivinfotech.com\/blog\/network-time-protocol-ntp-in-2025\/\">The Ultimate Guide to Network Time Protocol (NTP) in 2025<\/a><\/p>\n<\/li>\n<li>\n<p class=\"entry-title\"><a href=\"https:\/\/www.kaashivinfotech.com\/blog\/what-is-ping-meaning-explained-2025\/\">What Is Ping? [2025 Guide] Ping Meaning in Networking, Command, Test &amp; More Explained<\/a><\/p>\n<\/li>\n<\/ul>\n<\/div>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Assuming you have ever worked in networking (or even been allowed to peep into the obscure realm of packets flying across wires), you must have heard of Switched Port Analyzer (SPAN). There is something I want to tell you&#8211;I initially heard of it and believed that it is some complicated instrument, which only large technological [&hellip;]<\/p>\n","protected":false},"author":8,"featured_media":15846,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8983],"tags":[9141,9140,9142,9143,9136,9139,9138,9137],"class_list":["post-15835","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-networking","tag-how-to-configure-span-port-on-cisco-switch-9300","tag-span-port-configuration","tag-switch-port-analyzer-span","tag-switch-span-port","tag-switched-port-analyzer-cisco","tag-switched-port-analyzer-example","tag-switched-port-analyzer-pdf","tag-switched-port-analyzer-vlan"],"_links":{"self":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts\/15835","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/comments?post=15835"}],"version-history":[{"count":0,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/posts\/15835\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/media\/15846"}],"wp:attachment":[{"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/media?parent=15835"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/categories?post=15835"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kaashivinfotech.com\/blog\/wp-json\/wp\/v2\/tags?post=15835"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}