# IPv6 Router Advertisement Forwarding Disrupts netlab VRRPv3 Integration Tests

DevFeed: [IPv6 Router Advertisement Forwarding Disrupts netlab VRRPv3 Integration Tests](<https://devfeed.tech/articles/ipv6-and-the-revenge-of-the-stupid-bridges-11159.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/03/stupid-bridges-strike-again/>)

Published: 2025-03-24T07:08:00Z

Content type: article

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [networking](<https://devfeed.tech/topics/networking.md>), [Networks](<https://devfeed.tech/topics/networks.md>), [Linux](<https://devfeed.tech/topics/linux.md>), [Containers](<https://devfeed.tech/topics/containers.md>), [Testing](<https://devfeed.tech/topics/testing.md>), [Integration testing](<https://devfeed.tech/topics/integration-testing.md>)

Tags: [bridging](<https://devfeed.tech/tags/bridging.md>), [cisco](<https://devfeed.tech/tags/cisco.md>), [container](<https://devfeed.tech/tags/container.md>), [integration-testing](<https://devfeed.tech/tags/integration-testing.md>), [ipv6](<https://devfeed.tech/tags/ipv6.md>), [linux](<https://devfeed.tech/tags/linux.md>), [netlab](<https://devfeed.tech/tags/netlab.md>), [networks](<https://devfeed.tech/tags/networks.md>)

## AI overview

This technical blog post investigates VRRPv3 IPv6 integration-test failures in netlab. It finds that an Arista cEOS container forwarded IPv6 router advertisements between two LAN segments because newly appearing interfaces were enabled in VLAN 1, causing some hosts to treat both prefixes as directly connected. A workaround was implemented in netlab 1.9.4.

## Source excerpt

This blog post describes another "OMG, this cannot possibly be true" scenario discovered during the netlab VRRP integration testing. I wanted to test whether we got the nasty nuances of VRRPv3 IPv6 configuration right on all supported platforms and created a simple lab topology in which the device-under-test and an Arista cEOS container would be connected to two IPv6 networks (Arista EOS is a lovely device to use when testing a VRRP cluster because it produces JSON-formatted show vrrp printouts). Most platforms worked as expected, but Aruba CX, Cumulus Linux with NVUE, and Dell OS10 consistently failed the tests. We were stumped until Jeroen van Bemmel discovered that the Arista container forwards IPv6 router advertisements between the two LAN segments. Read more ...