1. M

    pve-firewall cannot be used because fragmented packets are not supported

    Hello all, we operate a proxmox cluster with 3 nodes. The network settings look like this on all 3 nodes: As you see the bridge ist VLAN aware. We need this, because some of our machines need access to more than 32 VLANs, but we cannot add more than 32 NICs. So the VMs then have 1 interface...
  2. G

    Proxmox fluctuation in Network Speed via Iperf

    I got an issue since a while that the network connection speed drops on my Proxmox. (I check it with Iperf3) I have an 2.5 Gbit connection but sometimes the speed drops to 1 Gbit or sometimes even 100 Mbit. The clue is. I get this resolved 99% of the time when I change the MTU in the GUI from...
  3. S

    Weird issue with MTU = 16182 : Windows client cannot open files on LXC Samba server

    Lately without me doing any configuration change, except for updating the Proxmox host (7.4-17 now) and the LXC Guest Samba server, I ran into a huge headache with connecting from my Windows 11 SMB client to the above Samba server. Basically, whenever I tried to open the drive or browse the...
  4. I

    ovs made bond with vlan and custom mtu

    Hi! I apologize to open up another lot-discussed-topic, at the moment everything looks to me working well but still i would like to get confirmation if my thinking is good and specific configuration is good. My effort is computer has four physical interfaces and two of them are 10g and...
  5. S

    MTU related info spammed in log.

    In my SysLogs, I'm seeing the following over and over, anywhere form every few minutes to every hour or so. Apr 22 13:54:55 server9 corosync[3275313]: [KNET ] host: host: 1 (passive) best link: 0 (pri: 1) Apr 22 13:54:55 server9 corosync[3275313]: [KNET ] host: host: 1 has no active links...
  6. T

    Incorrect MTU calculation when CT sending packets over bridged VXLAN port

    We have an overlay network (configured as described below) which worked fine on PVE6.4 but after migrating the containers to a PVE 7.2 node have noticed some odd behavior, with packets above a certain size being discarded by the vxlan interface, but only when sent from a container, VMs continue...
  7. D

    Slow backups and poor performance of VMs during backups

    I am hoping I provide enough info off the bat to give a good idea of what is going on. But I am a little lost and just have a lot of questions I guess. I will also do my best to update with what has been answered, and link or say what the answer/solution was. The setup: So we have 4 HP DL360p...
  8. S

    [ovs] mtu on several devices are "wrong" after a reboot

    Hey there, after testing the behavior a bit, there are probably two bugs I noticed. One "bug" is resolved with an ifreload or with ifup -a. 1. A ovs_bonds Interface have the mtu of 1500 - despite setting it to 9000 (ovs_mtu 9000). netstat -i (only bond0 and vmbr9) Kernel Interface table Iface...
  9. J

    [SOLVED] Unable to Allocate Image on GlusterFS

    Throwing this solution up in case someone else runs into the issue. Scroll down to the bottom for the key Take Aways and dev recommendations. Environment 3x PVE 7.0-11 nodes clustered together Every node has a ZFS pool with a GlusterFS brick on it Glusterd version 9.2 Gluster is configured in a...
  10. C

    vlan mtu not set

    I have a strange issue, that the mtu size of vlans are not set. My /etc/network/interfaces: # network interface settings; autogenerated # Please do NOT modify this file directly, unless you know what # you're doing. # # If you want to manage parts of the network configuration manually, # please...
  11. O

    HELP: Wireguard and OpenVPN cap out at 23mbps

    Hi, I am running Proxmox on a HP Thinclient T630. The internet connection of the server is 100down/50up but over both WG and OVPN I get maximum 23-25mbps either way. I tried them in both a VM and a LXC with no change. I played with the MTU from 1420/1500 all the way to 1200 - again no...
  12. G

    Bridge does not inherit MTU from ports in PVE 7 using ifupdown2

    Consider the following example config in /etc/network/interfaces: auto lo iface lo inet loopback auto mgmt0 iface mgmt0 auto mgmt1 iface mgmt1 auto north0 iface north0 mtu 9000 auto north1 iface north1 mtu 9000 auto bond0 iface bond0 bond-slaves north0 north1 bond-miimon 100...
  13. S

    Setting MTU globally

    Hi. I have a requirement that all traffic leaving proxmox is using a certain MTU lower than 1500, including traffic from VMs What is the way to configure this? Should we just set the MTU on the public interface and the bridge? To ensure all traffic is using a certain MTU, must the MTU be...
  14. Dunuin

    MTU and Proxmox?

    Hi, Right now I'm rebuilding my network because I switched the servers from Gbit to 10G but I'm not sure how to optimize the MTU. 1.) Is it useful to switch from 1500 MTU to 9000 MTU jumboframes? I've heard that this would reduce the number of packets and because of that would increase the...
  15. L

    New cluster vpn mtu gre problem

    Hi, I'm trying to setup a new cluster with three nodes throw VPN to make a small HA. I'm usinc tinc for the vpn and ovs to bridge the node with gre. It's working quiet well but i'm getting some issue with ssh and...
  16. T

    [SOLVED] Possible MTU misconfiguration detected

    Hello, I changed the MTU on both nodes to 8988, and I got the likely full bandwidth. But after some minutes all breaks. ISCSI won't work and in the syslog at both nodes is something like this: un 28 16:22:03 pangolin corosync[2211]: [KNET ] pmtud: possible MTU misconfiguration detected. kernel...
  17. X

    Shutdown of VM/CT changes Bridge MTU

    Hello PVE-Community, I recently setup a three node cluster and I have this weird issue where the shutdown of a VM or CT changes the MTU of the bridge that is used for communication between VM/CTs and also for the cluster link. The MTU is changed to whatever is configured at the primary...
  18. A

    Speed problem with MTU 9000 hypervisor and MTU 1500 VMs

    Hello, We have speed loss with mtu set to 9000 and WMs using a mtu of 1500. Here is the configuration, we have 2 proxmox connected to a switch : vmbr1 is an ovs bridge with mtu 9000. Bond0 is an ovs bond with mtu 9000, each member of the bond has a mtu of 9000 using pre-up, and is link vmbr1...
  19. S

    Probleme mit MTU

    Hallo. Wir haben aktuell Probleme mit der MTU Size. Ich beschreibe hier kurz unsere Umgebung: Wir haben eine NetApp stehen die per NFS an Cisco 3750 Switches hängt. Die NFS Shares werden von einem PVE Cluster (Dell R720 Server) der aus fünf Nodes besteht gemountet. Die NetApp und die Switches...
  20. C

    Message too long, mtu=1500 on OVSInt Port

    I just ran into trouble with enabling multicast on the OVSIntPorts. My cluster network uses 2 Intel 10G ports bonded together, 1 Bridge, 2 IntPorts. On the switch side I added a trunk and enabled jumboframes. After setting (according to the wiki) MTU to 8996 ceph cluster stops working, while...


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