--- title: Fix AS-Path in Environments Reusing BGP AS Numbers « BGP... description: A hands-on BGP lab exercise that walks through configuring AS override on Provider Edge (PE) routers to fix AS-path issues when multiple customer sites share... canonical: https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Fix AS-Path in Environments Reusing BGP AS Numbers « BGP Labs | daily.dev og:description: A hands-on BGP lab exercise that walks through configuring AS override on Provider Edge (PE) routers to fix AS-path issues when multiple customer sites share... og:url: https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c og:image: https://api.daily.dev/og/posts/o9SncqO8c.png og:image:alt: Fix AS-Path in Environments Reusing BGP AS Numbers « BGP Labs 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. # Fix AS-Path in Environments Reusing BGP AS Numbers « BGP Labs **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 6 min read · 0 upvotes · 0 comments ## Summary A hands-on BGP lab exercise that walks through configuring AS override on Provider Edge (PE) routers to fix AS-path issues when multiple customer sites share the same BGP AS number. The problem arises because CE routers reject routes where their own AS appears in the path. The solution is to configure 'neighbor as-override' on PE1 and PE2 EBGP sessions, replacing the customer AS number with the provider AS number, then resending updates with a soft reset. The lab uses a 4-router topology (PE1, PE2, CE1, CE2) with netlab for automated configuration, and supports validation on FRRouting or Arista EOS CE routers. A key side effect noted is that AS override disables BGP loop prevention, causing CE routers to see two copies of their own prefixes. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I fix BGP routes being rejected when multiple customer sites use the same AS number? Configure 'neighbor as-override' on the Provider Edge EBGP sessions facing each customer. This replaces the customer AS number in the AS path with the provider's own AS number before advertising routes to other CE routers. After enabling it, trigger a soft outbound reset with a command like 'clear ip bgp soft out' to resend updated BGP advertisements. Note that this disables BGP loop prevention, so CE routers will see two copies of their own prefixes. _Engineers dealing with BGP AS reuse across customer sites track solutions like this on daily.dev._ ### Does Arista EOS support BGP AS override? Arista EOS does not support the AS override functionality. It is available on FRRouting and other BGP implementations, but not on Arista EOS. Additionally, Arista EOS does not display routes dropped by the BGP loop prevention logic even when BGP soft reconfiguration is configured. _Networking engineers choosing between BGP platforms for multi-site deployments find platform capability comparisons on daily.dev._ ## Similar posts on daily.dev - [Enforcing the First AS in BGP AS\_PATHs](https://daily.dev/posts/enforcing-the-first-as-in-bgp-as-paths-yx1xiadkj) · Cloudflare · 0 upvotes · 0 comments --- Tags: [#networking](https://daily.dev/tags/networking), [#bgp](https://daily.dev/tags/bgp) [View this post on daily.dev](https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c) ```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":"Fix AS-Path in Environments Reusing BGP AS Numbers « BGP Labs","url":"https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c"},"datePublished":"2026-08-11T08:52:47.920Z","dateModified":"2026-08-11T09:10:16.047Z","description":"A hands-on BGP lab exercise that walks through configuring AS override on Provider Edge (PE) routers to fix AS-path issues when multiple customer sites share...","image":"https://media.daily.dev/image/upload/s--58gMhC4P--/f_auto/v1722860399/public/Placeholder%2012","thumbnailUrl":"https://media.daily.dev/image/upload/s--58gMhC4P--/f_auto/v1722860399/public/Placeholder%2012","isAccessibleForFree":true,"articleSection":"ipSpace.net Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"ipSpace.net Blog","logo":"https://media.daily.dev/image/upload/s--xS7E82MT--/f_auto,q_auto/v1786438303/logos/ipspace?_a=BAMAMicg0","url":"https://daily.dev/sources/ipspace"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"networking,bgp","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"ipSpace.net Blog","item":"https://daily.dev/sources/ipspace"},{"@type":"ListItem","position":3,"name":"Fix AS-Path in Environments Reusing BGP AS Numbers « BGP Labs"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/fix-as-path-in-environments-reusing-bgp-as-numbers-bgp-labs-o9sncqo8c#faq","mainEntity":[{"@type":"Question","name":"How do I fix BGP routes being rejected when multiple customer sites use the same AS number?","acceptedAnswer":{"@type":"Answer","text":"Configure 'neighbor as-override' on the Provider Edge EBGP sessions facing each customer. This replaces the customer AS number in the AS path with the provider's own AS number before advertising routes to other CE routers. After enabling it, trigger a soft outbound reset with a command like 'clear ip bgp soft out' to resend updated BGP advertisements. Note that this disables BGP loop prevention, so CE routers will see two copies of their own prefixes. Engineers dealing with BGP AS reuse across customer sites track solutions like this on daily.dev."}},{"@type":"Question","name":"Does Arista EOS support BGP AS override?","acceptedAnswer":{"@type":"Answer","text":"Arista EOS does not support the AS override functionality. It is available on FRRouting and other BGP implementations, but not on Arista EOS. Additionally, Arista EOS does not display routes dropped by the BGP loop prevention logic even when BGP soft reconfiguration is configured. Networking engineers choosing between BGP platforms for multi-site deployments find platform capability comparisons on daily.dev."}}]} ```