{"id":11307,"date":"2011-12-02T18:43:49","date_gmt":"2011-12-02T18:43:49","guid":{"rendered":"https:\/\/www.techopedia.com\/definition\/variable-length-subnet-mask\/"},"modified":"2011-12-02T18:49:40","modified_gmt":"2011-12-02T18:49:40","slug":"variable-length-subnet-mask","status":"publish","type":"definition","link":"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm","title":{"rendered":"Variable Length Subnet Mask"},"content":{"rendered":"<h2><span id=\"what_does_variable_length_subnet_mask_mean\">What Does Variable Length Subnet Mask Mean?<\/span><\/h2>\n<p>A Variable Length Subnet Mask (VLSM) is a numerical masking sequence, or IP address subset, based on overall network requirements. A VLSM allows a network administrator to use long masks for networks with few hosts and short masks for networks with multiple hosts. A VLSM is used with a VLSM router and must have routing protocol support.<\/p>\n<p>A VLSM is also known as a classless Internet Protocol (IP) address.<\/p>\n<h2><span id=\"techopedia_explains_variable_length_subnet_mask\">Techopedia Explains Variable Length Subnet Mask<\/span><\/h2>\n<p>Key VLSM features include:<\/p>\n<ul>\n<li>Simple network configuration<\/li>\n<li>Network IP addressing through empty subnet filling<\/li>\n<li>Greater efficiency than fixed-length subnet masks (FLSM)<\/li>\n<li>Streamlined routing, where a router functions only with a VLSM sequence, versus a full IP address<\/li>\n<\/ul>\n<p>VLSMs are used by a variety of network systems and services, including:<\/p>\n<ul>\n<li>Intermediate System to Intermediate System Protocol (IS-IS)<\/li>\n<li>Border Gateway Protocol (BGP)<\/li>\n<li>Enhanced Interior Gateway Routing Protocol (EIGRP)<\/li>\n<li>Cisco&#8217;s Open Shortest Path First (OSPF)<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>What Does Variable Length Subnet Mask Mean? A Variable Length Subnet Mask (VLSM) is a numerical masking sequence, or IP address subset, based on overall network requirements. A VLSM allows a network administrator to use long masks for networks with few hosts and short masks for networks with multiple hosts. A VLSM is used with [&hellip;]<\/p>\n","protected":false},"author":7813,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","format":"standard","meta":{"_acf_changed":false,"_lmt_disableupdate":"","_lmt_disable":"","om_disable_all_campaigns":false,"footnotes":""},"definitioncat":[219],"class_list":["post-11307","definition","type-definition","status-publish","format-standard","hentry","definitioncat-networks"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v24.2 (Yoast SEO v24.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>What is Variable Length Subnet Mask (VLSM)? - Definition from Techopedia<\/title>\n<meta name=\"description\" content=\"This definition explains the meaning of Variable Length Subnet Mask and why it matters.\" \/>\n<meta name=\"robots\" content=\"noindex, follow\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Variable Length Subnet Mask\" \/>\n<meta property=\"og:description\" content=\"This definition explains the meaning of Variable Length Subnet Mask and why it matters.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm\" \/>\n<meta property=\"og:site_name\" content=\"Techopedia\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/techopedia\/\" \/>\n<meta property=\"article:modified_time\" content=\"2011-12-02T18:49:40+00:00\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:site\" content=\"@techopedia\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm\"},\"author\":{\"name\":\"Margaret Rouse\",\"@id\":\"https:\/\/www.techopedia.com\/#\/schema\/person\/f5dd538e31ee352d105b8af36c4268a5\"},\"headline\":\"Variable Length Subnet Mask\",\"datePublished\":\"2011-12-02T18:43:49+00:00\",\"dateModified\":\"2011-12-02T18:49:40+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm\"},\"wordCount\":158,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.techopedia.com\/#organization\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm#respond\"]}],\"articleSection\":\"\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm\",\"url\":\"https:\/\/www.techopedia.com\/definition\/25932\/variable-length-subnet-mask-vlsm\",\"name\":\"What is Variable Length Subnet Mask (VLSM)? 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