# ArubaCX VXLAN Interoperability Fails with VNIs Above 65535

DevFeed: [ArubaCX VXLAN Interoperability Fails with VNIs Above 65535](<https://devfeed.tech/articles/dear-arubacx-vxlan-vni-has-24-bits-11178.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/05/arubacx-vxlan-vni-arp/>)

Published: 2025-05-29T05:55:00Z

Content type: opinion

Language: en

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

Topics: [VXLAN](<https://devfeed.tech/topics/vxlan.md>), [networking](<https://devfeed.tech/topics/networking.md>), [interoperability](<https://devfeed.tech/topics/interoperability.md>), [Testing](<https://devfeed.tech/topics/testing.md>)

Tags: [configuration](<https://devfeed.tech/tags/configuration.md>), [interoperability](<https://devfeed.tech/tags/interoperability.md>), [netlab](<https://devfeed.tech/tags/netlab.md>), [networking](<https://devfeed.tech/tags/networking.md>), [testing](<https://devfeed.tech/tags/testing.md>), [vxlan](<https://devfeed.tech/tags/vxlan.md>)

## AI overview

The article reports that an ArubaCX virtual machine failed inter-vendor VXLAN integration tests when using a VNI of 101000. Packet capture showed the configured VNI being encoded as 35646, the lower 16 bits of 101000. ArubaCX also refused packets with the correct VNI. The suggested workarounds are using VNIs 5000 and 5001 in the tests, or using netlab 2.0.1, which rejects ArubaCX VNI values above 65535.

## Source excerpt

I thought I've seen it all, but the networking vendors (and their lack of testing) never cease to amaze me. Today's special: ArubaCX software VXLAN implementation. We decided it's a good idea to rewrite the VXLAN integration tests to use one target device and one FRR container to test inter-vendor VXLAN interoperability. After all, what could possibly go wrong with a simple encapsulation format that could be described on a single page? Everything worked fine (as expected), except for the ArubaCX VM (running release Virtual.10.15.1005, build ID AOS-CX:Virtual.10.15.1005:9d92f5caa6b6:202502181604), which failed every single test. Read more ...