SOLVED: Local VM with VLAN tag disconnects the physical host

A

atatury

Member
Oct 29, 2023
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Hello all,

I created a local VM (with local-lvm storage) with an interface with vlan tag 10. Vmbr0 bridge which this VM connected is vlan aware and physical host management is also connected to this bridge and it is also on vlan 10.
When VM is started, communication with host is disconnected and only way is to reboot. Whem VM is created without VLAN tag, everything is OK. Host runs Proxmox 9.2 and my /etc/network/interfaces is attached. I also give the "qm config" output:

Code: 
agent: 1
boot: order=scsi0;ide2;net0
cores: 2
cpu: host
ide2: local:iso/ubuntu-24.04.4-live-server-amd64.iso,media=cdrom,size=3325654K
memory: 8192
meta: creation-qemu=11.0.0,ctime=1783589846
name: 2404-test
net0: virtio=BC:24:11:E7:E8:CB,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-100-disk-0,iothread=1,size=300G
scsihw: virtio-scsi-single
smbios1: uuid=f159d89b-d9bb-4aa2-9ae6-af8d44bf6388
sockets: 1
vmgenid: 8bba09de-920e-41c4-9485-8b97cda34069

Can you please help?

Thank you..
 

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Is vlan_filtering actually enabled for vmbr0? You can check via:
Code: 
ip -details link show vmbr0
 
Here is the output of "ip -details link show vmbr0" from the physical host:

9: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether f4:1d:6b:f8:6d:f6 brd ff:ff:ff:ff:ff:ff promiscuity 0 allmulti 0 minmtu 68 maxmtu 65535
bridge forward_delay 0 hello_time 200 max_age 2000 ageing_time 30000 stp_state 0 priority 32768 vlan_filtering 0 vlan_protocol 802.1Q bridge_id 8000.f4:1d:6b:f8:6d:f6 designated_root 8000.f4:1d:6b:f8:6d:f6 root_port 0 root_path_cost 0 topo
logy_change 0 topology_change_detected 0 hello_timer 0.00 tcn_timer 0.00 topology_change_timer 0.00 gc_timer 14.43 fdb_n_learned 22 fdb_max_learned 0 vlan_default_pvid 1 vlan_stats_enabled 0 vlan_stats_per_port 0 group_fwd_mask 0 gr
oup_address 01:80:c2:00:00:00 mcast_snooping 1 no_linklocal_learn 0 mcast_vlan_snooping 0 mst_enabled 0 mcast_router 1 mcast_query_use_ifaddr 0 mcast_querier 0 mcast_hash_elasticity 16 mcast_hash_max 4096 mcast_last_member_count 2 mcast_startu
p_query_count 2 mcast_last_member_interval 100 mcast_membership_interval 26000 mcast_querier_interval 25500 mcast_query_interval 12500 mcast_query_response_interval 1000 mcast_startup_query_interval 3125 mcast_stats_enabled 0 mcast_igmp_versio
n 2 mcast_mld_version 1 nf_call_iptables 0 nf_call_ip6tables 0 nf_call_arptables 0 addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 gso_ipv4_max_size 6
5536 gro_ipv4_max_size 65536

Looks like it's not enabled. Can you also check please?

Thank you..
 
Yes, it seems like it is not enabled - did you apply the network configuration after setting it in /etc/network/interfaces ? It's weird that vlan_filtering is 0, judging from your interfaces file.

This also explains why it takes down the VLAN on the host, because then a new bridge vmbr0v10 is created, with bond0.10 as bridge_port, which "blackholes" the VLAN 10 from vmbr0. You'll need to ensure that vmbr0 is VLAN-aware (usually by reapplying the network configuration, although I'd double-check if vlan_filtering survives a reboot) and then it should work.
 
Although my /etc/network/interfaces file does contain "bridge-vlan-aware yes" line but GUI doesn't show up that vmbr0 is vlan aware !?? It seems that some kind of typo (or tab usage) causes that it's not enabled. I enabled it from the GUI and all seems working. Thank you very much for your support Shanreich, appreciated.

Best regards..
 
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