--- title: Why Do We Need IBGP Full Mesh? « ipSpace.net blog description: A historical explanation of why IBGP requires a full mesh topology. BGP version 1 (RFC 1105, 1989) was designed as a simple replacement for EGP, with no... canonical: https://daily.dev/posts/why-do-we-need-ibgp-full-mesh-ipspace-net-blog-quhhnx3sh twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Why Do We Need IBGP Full Mesh? « ipSpace.net blog | daily.dev og:description: A historical explanation of why IBGP requires a full mesh topology. BGP version 1 (RFC 1105, 1989) was designed as a simple replacement for EGP, with no... og:url: https://daily.dev/posts/why-do-we-need-ibgp-full-mesh-ipspace-net-blog-quhhnx3sh og:image: https://api.daily.dev/og/posts/QuHHNX3sH.png og:image:alt: Why Do We Need IBGP Full Mesh? « 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. # Why Do We Need IBGP Full Mesh? « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 4 min read · 0 upvotes · 0 comments ## Summary A historical explanation of why IBGP requires a full mesh topology. BGP version 1 (RFC 1105, 1989) was designed as a simple replacement for EGP, with no intra-AS loop detection mechanism. The designers explicitly stated that if BGP was used within an AS, all BGP gateways must have direct sessions with each other (full mesh). Early networks avoided this requirement by redistributing BGP routes into IGP (using bgp synchronization). As BGP evolved through versions 2, 3, and 4, the full mesh requirement became a scalability bottleneck in large ISP networks, eventually leading to route reflectors (RFC 1966) and confederations (RFC 1965) in 1996. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does IBGP require a full mesh between peers? IBGP requires a full mesh because BGP version 1 had no mechanism to detect intra-AS routing loops. The split-horizon rule — never advertise an IBGP-learned route to another IBGP peer — prevents loops only if all IBGP peers are fully meshed. RFC 1105 explicitly states that BGP gateways within a single AS 'MUST have direct BGP sessions with each other (the BGP sessions should form a complete graph).' _Network engineers working through BGP design decisions find the protocol history and RFC context on daily.dev._ ### What were the alternatives to IBGP full mesh in early BGP deployments? Early BGP deployments avoided IBGP full mesh by redistributing BGP routes into IGP. The bgp synchronization feature in Cisco IOS required BGP prefixes to be present in an IGP before advertising them to other autonomous systems. When redistributing into OSPF, the first AS in the AS-path was copied into the OSPF tag, allowing egress routers to recreate a short AS-path when redistributing back into BGP. _Keeping up with BGP evolution and legacy design trade-offs is easier when daily.dev surfaces the right deep-dives for you._ ### When were BGP route reflectors introduced and what RFC defines them? BGP route reflectors were introduced in RFC 1966, published in June 1996, as a solution to the IBGP full mesh scalability bottleneck in large service provider networks. BGP confederations were introduced at the same time in RFC 1965, also June 1996. Route reflectors were first implemented in Cisco IOS software release 11.1. _Engineers scaling BGP in large networks track RFC milestones and implementation details like these on daily.dev._ --- Tags: [#networking](https://daily.dev/tags/networking), [#bgp](https://daily.dev/tags/bgp) [View this post on daily.dev](https://daily.dev/posts/why-do-we-need-ibgp-full-mesh-ipspace-net-blog-quhhnx3sh) ```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":"Why Do We Need IBGP Full Mesh? « ipSpace.net blog","url":"https://daily.dev/posts/why-do-we-need-ibgp-full-mesh-ipspace-net-blog-quhhnx3sh","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/why-do-we-need-ibgp-full-mesh-ipspace-net-blog-quhhnx3sh"},"datePublished":"2026-08-11T08:51:56.903Z","dateModified":"2026-08-11T09:00:15.945Z","description":"A historical explanation of why IBGP requires a full mesh topology. 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