After contrail compute reboot, in a contrail openstack environment, it was noticed that, multiple VMs went unreachable. This problem does not happen in all computes but some of them.

multiple VMs went unreachable after compute reboot.

Noticed below lines in vrouter container logs on the compute.

UVHOST: error connecting uvhost socket FD 108 to /var/run/vrouter/uvh_vif_tap004f9078-02: No such file or directory (2)

Find the tap interface name from CLI using below command

# contrail-tools vif --list

1. The reason found to be socket file for the tap interface were not present.

# ls -lthr /var/run/vrouter/ | grep <tap interface name>

2. Confirm if there are no issues in a new socket file creation by creating a new VM in the compute.

3. If no issues, noticed in Step 2, Consider live migrating the VMs back and forth between different computes.