This knowledge base has moved to the documentation site. Please visit the knowledge base here for the most up to date content. This site is no longer maintained.

Unable to Bring up TUN/TAP Devices



TUN/TAP devices other than swp* interfaces do not pass traffic.


  • Cumulus Linux 2.2.x


Upgrade to Cumulus Linux 2.5.0 or later.  This issue was previously tracked by internal engineering defect CM-3788.

Root Cause

The Cumulus Linux patch network-tun-no-carrier.patch disabled default TUN/TAP behavior in order to prevent link flap during switchd restart.


This support portal has moved

Cumulus Networks is now part of the NVIDIA Networking Business Unit! The NVIDIA Cumulus Global Support Services (GSS) team has merged its operations with the NVIDIA Mellanox support services team.

You can access NVIDIA Cumulus support content from the Mellanox support portal.

You open and update new cases on the Mellanox support portal. Any previous cases that have been closed have been migrated to the Mellanox support portal.

Cases that are still open on the Cumulus portal will continue to be managed on the Cumulus portal. Once these cases close, they will be moved to the Mellanox support portal.

Powered by Zendesk