GitHub user rbaweja closed a discussion: Net Creation Fails on Second KVM Host Due to Invalid Bridge Name Format
### problem Summary: When adding a second KVM host with identical bridge and VLAN configuration to an existing zone, CloudStack fails to create a VNet interface, throwing an error due to an invalid bridge name. ### versions Environment: CloudStack Version: [e.g., 4.20.0.0] Hypervisor: KVM Host OS: Ubuntu 24.04 (or your exact OS) Network Setup: cloudbr0: Management (Access) cloudbr1: Guest (VLAN-aware, native + trunked VLANs) cloudbr3: Public (VLAN-aware, trunked, tagged at ACS level) ### The steps to reproduce the bug 1. Create a working zone with one KVM host using ens1f0np0 for guest VLAN bridge (cloudbr1). 2. Add another KVM host with the same physical interface name. 3. Deploy a guest VM with a VLAN-enabled network (e.g., VLAN ID 1996). 4. Observe that the bridge creation fails on the second host. ### What to do about it? Observed Behavior Agent log from new host shows: Execution of process for command [.../modifyvlan.sh -v 1996 -p ens1f0np0 -b brens1f0np0-1996 -o add ] failed. Error: argument "brens1f0np0-1996" is wrong: "name" not a valid ifname ... line 59: /proc/sys/net/ipv6/conf/brens1f0np0-1996/disable_ipv6: No such file or directory Cannot find device "brens1f0np0-1996" Failed to create br: brens1f0np0-1996 Root Cause The bridge name brens1f0np0-1996 exceeds the 15-character IFNAMSIZ limit imposed by the Linux kernel. Resulting bridge creation fails due to invalid interface name. Expected Behavior CloudStack should: Generate compliant bridge names (≤15 characters). OR pre-validate final bridge names before attempting creation. OR use a shortened/hashed format (e.g., brv1996, brg123, etc.) Temporary Workaround Renaming physical interfaces to shorter names (e.g., eth0) avoids name length issues — but this is not sustainable or ideal in managed deployments. Suggested Fix Update the BridgeVifDriver or modifyvlan.sh logic to: Enforce safe-length bridge names Apply a safe naming convention that avoids appending full interface names + VLAN IDs blindly GitHub link: https://github.com/apache/cloudstack/discussions/11148 ---- This is an automatically sent email for users@cloudstack.apache.org. To unsubscribe, please send an email to: users-unsubscr...@cloudstack.apache.org
