--- title: Comparing IP and CLNP: Finding Adjacent Nodes «... description: A deep-dive comparison of how TCP/IP and CLNP (OSI networking) solve the problem of finding adjacent nodes on a network segment. TCP/IP uses subnet masks... canonical: https://daily.dev/posts/comparing-ip-and-clnp-finding-adjacent-nodes-ipspace-net-blog-rbbqrcnfw twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Comparing IP and CLNP: Finding Adjacent Nodes « ipSpace.net blog | daily.dev og:description: A deep-dive comparison of how TCP/IP and CLNP (OSI networking) solve the problem of finding adjacent nodes on a network segment. TCP/IP uses subnet masks... og:url: https://daily.dev/posts/comparing-ip-and-clnp-finding-adjacent-nodes-ipspace-net-blog-rbbqrcnfw og:image: https://api.daily.dev/og/posts/RBBQrcnfw.png og:image:alt: Comparing IP and CLNP: Finding Adjacent Nodes « ipSpace.net blog og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Comparing IP and CLNP: Finding Adjacent Nodes « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 5 min read · 0 upvotes · 0 comments ## Summary A deep-dive comparison of how TCP/IP and CLNP (OSI networking) solve the problem of finding adjacent nodes on a network segment. TCP/IP uses subnet masks combined with ARP (IPv4) or Neighbor Discovery (IPv6) to determine adjacency and resolve MAC addresses. CLNP takes a fundamentally different approach: since NSAP addresses belong to nodes rather than interfaces, hosts and routers periodically broadcast Hello messages (ESH/ISH) that neighbors collect to build an adjacency cache including MAC addresses. The post also explores an off-topic but practical angle: how VMware ESXi uses the long-obsolete RARP protocol to announce VM location after live migration, compensating for IP's lack of a native host-advertisement mechanism equivalent to CLNP's Hello messages. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does CLNP determine if a node is adjacent when NSAP addresses belong to nodes not interfaces? CLNP nodes cannot use address prefix matching to determine adjacency because NSAP addresses are node-scoped, not interface-scoped. Instead, every CLNP node broadcasts periodic Hello messages — End-System Hellos (ESH) from hosts and Intermediate System Hellos (ISH) from routers. Each node listens to these on its LAN segments and builds a neighbor cache mapping adjacent NSAPs to outgoing interfaces and MAC addresses, which is functionally equivalent to host routes pointing to interfaces. _Engineers working with OSI or IS-IS internals find protocol comparisons like this on daily.dev._ ### Why does VMware ESXi send RARP packets when a virtual machine is migrated? VMware ESXi sends RARP packets after a VM migration because ESXi does not listen to ARP requests and replies, so it cannot generate gratuitous ARP on the VM's behalf. RARP packets carry only MAC addresses — which ESXi knows — and no IP addresses, making them usable without tracking VM IP state. This signals to the network that the VM's MAC address is now reachable from a new location. _Teams managing VM mobility and data center networking track workarounds like this on daily.dev._ ## Similar posts on daily.dev - [Your router still depends on a 44-year-old protocol to locate every device on your network](https://daily.dev/posts/your-router-still-depends-on-a-44-year-old-protocol-to-locate-every-device-on-your-network-imka9mnej) · XDA Developers · 0 upvotes · 0 comments - [How NetworkManager uses eBPF to support CLAT and IPv6-mostly](https://daily.dev/posts/how-networkmanager-uses-ebpf-to-support-clat-and-ipv6-mostly-fiiow2hx2) · Red Hat Developer · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/comparing-ip-and-clnp-finding-adjacent-nodes-ipspace-net-blog-rbbqrcnfw) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Comparing IP and CLNP: Finding Adjacent Nodes « ipSpace.net blog","url":"https://daily.dev/posts/comparing-ip-and-clnp-finding-adjacent-nodes-ipspace-net-blog-rbbqrcnfw","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/comparing-ip-and-clnp-finding-adjacent-nodes-ipspace-net-blog-rbbqrcnfw"},"datePublished":"2026-08-11T08:51:53.026Z","dateModified":"2026-08-11T08:53:36.317Z","description":"A deep-dive comparison of how TCP/IP and CLNP (OSI networking) solve the problem of finding adjacent nodes on a network segment. 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