--- title: Sturgeon's Law, VRRPv3 Edition « ipSpace.net blog description: A deep dive into a VRRPv3 interoperability nightmare caused by ambiguous checksum calculation wording in RFC 5798. When testing a dozen platforms in netlab,... canonical: https://daily.dev/posts/sturgeon-s-law-vrrpv3-edition-ipspace-net-blog-wuyjvnnxa twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Sturgeon's Law, VRRPv3 Edition « ipSpace.net blog | daily.dev og:description: A deep dive into a VRRPv3 interoperability nightmare caused by ambiguous checksum calculation wording in RFC 5798. When testing a dozen platforms in netlab,... og:url: https://daily.dev/posts/sturgeon-s-law-vrrpv3-edition-ipspace-net-blog-wuyjvnnxa og:image: https://api.daily.dev/og/posts/wuyjvNNXA.png og:image:alt: Sturgeon's Law, VRRPv3 Edition « 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. # Sturgeon's Law, VRRPv3 Edition « ipSpace.net blog **[ipSpace.net Blog](https://daily.dev/sources/ipspace)** · 5 min read · 0 upvotes · 0 comments ## Summary A deep dive into a VRRPv3 interoperability nightmare caused by ambiguous checksum calculation wording in RFC 5798. When testing a dozen platforms in netlab, Arista EOS and FRR were found to include an IPv4 pseudo-header in VRRP checksums (borrowing from IPv6 rules), while Cisco IOS, Nexus OS, and most others do not. This mismatch causes each side to reject the other's packets as having invalid checksums, potentially resulting in two simultaneous VRRP masters on the same segment. RFC 9568 (April 2024) clarified that IPv4 VRRP checksums should NOT include a pseudo-header. Arista EOS can be fixed with `vrrp ipv4 checksum pseudo-header exclude`, and FRR has had `no vrrp checksum-with-ipv4-pseudoheader` since late 2022, though downstream distros like Cumulus Linux 5.10 and current VyOS Vagrant boxes may not yet have the fix available. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does Arista EOS refuse to yield VRRP master to Cisco IOS in a multi-vendor setup? Arista EOS and Cisco IOS use incompatible VRRPv3 checksum calculations for IPv4. EOS includes an IPv4 pseudo-header (borrowing from IPv6 rules) while Cisco IOS does not, causing each side to reject the other's advertisements as having invalid checksums. This can result in two simultaneous VRRP masters on the same segment. RFC 9568 clarified that IPv4 VRRP checksums must not include a pseudo-header. _Engineers running mixed-vendor VRRP segments track interoperability issues like this on daily.dev._ ### How do I fix Arista EOS VRRPv3 checksum incompatibility with other vendors? Use the command `vrrp ipv4 checksum pseudo-header exclude` on Arista EOS to make it RFC 9568-compliant. For FRR, the command `no vrrp checksum-with-ipv4-pseudoheader` has been available since late 2022. Note that downstream distros like Cumulus Linux 5.10 still ship an older FRR version without this fix, and current VyOS Vagrant boxes also lack the configuration knob. _Staying on top of vendor-specific VRRP fixes before a production outage is easier when the right posts surface on daily.dev._ ### What changed in RFC 9568 compared to RFC 5798 for VRRPv3 checksum calculation? RFC 9568 clarified that for IPv4 VRRPv3 messages, the checksum covers only the VRRP message itself and does not include a pseudo-header. For IPv6, the checksum still includes the pseudo-header. RFC 5798 was ambiguous on this point, referring to a pseudo-header without specifying that IPv4 has no such concept, leading to two incompatible implementation camps. _Developers navigating RFC-level protocol changes find the relevant discussions faster on daily.dev._ ## Similar posts on daily.dev - [The Never-Ending IPv6 Loopback Prefix Saga « ipSpace.net blog](https://daily.dev/posts/the-never-ending-ipv6-loopback-prefix-saga-ipspace-net-blog-4nlhgh10l) · ipSpace.net Blog · 0 upvotes · 0 comments - [IPng Networks](https://daily.dev/posts/ipng-networks-u37jx9af5) · IPng Networks · 0 upvotes · 0 comments - [Multivendor SR-MPLS « ipSpace.net blog](https://daily.dev/posts/multivendor-sr-mpls-ipspace-net-blog-qekokwduk) · ipSpace.net Blog · 0 upvotes · 0 comments --- Tags: [#networking](https://daily.dev/tags/networking) [View this post on daily.dev](https://daily.dev/posts/sturgeon-s-law-vrrpv3-edition-ipspace-net-blog-wuyjvnnxa) ```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":"Sturgeon's Law, VRRPv3 Edition « ipSpace.net blog","url":"https://daily.dev/posts/sturgeon-s-law-vrrpv3-edition-ipspace-net-blog-wuyjvnnxa","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/sturgeon-s-law-vrrpv3-edition-ipspace-net-blog-wuyjvnnxa"},"datePublished":"2026-08-11T08:51:47.329Z","dateModified":"2026-08-24T06:58:41.905Z","description":"A deep dive into a VRRPv3 interoperability nightmare caused by ambiguous checksum calculation wording in RFC 5798. 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