1 VM loses network connection

B

Bart Brouwer

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Proxmox Subscriber
Jan 18, 2017
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Hello, i have 2 Proxmox servers (latest versions 4.4) configured into a cluster.
The network on both in Bridge mode.

6 VMs work fine on proxmox server 1
2 VM's work fine on proxmox server 2

But 1 vm dont work fine at server 2.
Ubuntu 16, phmyadmin and apache installed.
His own external IP.

The problem is:
The Ubuntu server loses network connection at a random time.
And this VM server network connection comes up again at a random time. this could be 5 minutes but also 1 hour.
When the network loses connection, i could not connect through SSH from home,
But when i logon on the proxmox VNC, and do: Ping to a website, the connection comes up again.
Looks like a 'sleeping' network connection?


I have installed the prxmox firewall and works fine with the other VM servers.

i disabled the lokal firewall at the VM's.
I allready changed the virtual network adapter from the ubuntu server from virtio to E1000 but no beter result. I rebooted the fysical server.
 

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Hi Bart
I am not sure here if it is a PVE problem or a routing problem.
Maybe you could try to configure the VM with a different IP address and see if the problem still occurs?
 
Hello Manu, tnx! at this moment i disabled the Proxmox firewall and testing if the problem occurs.
at this moment it goes well for 4 hours ;)

update: damn, losing connection again.
I have asked the provider for a routing check.

but there are no 'sleeping' modes available on ubuntu network connections?
 
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Tonight i swap 2 VM's external IP adresses.
And today the same server having the same problem. So, it couldnt be the routing :( (they checked also and coulnt find anything).

Could there be a network driver problem into ubuntu 16?
 
when you say the VM looses network connection as seen from the ouside how do you detect this ? what is doing MRTG in the background ? Ping ? It could be also that the problem comes from your hosting provider.

to debug this a bit, when the VM loses its network connection, can you check inside the VM if the (virtual ) Ethernet link is active :

ip --color link

you see LOWER_UP if the Virtual Ethernet link

if you see LOWER_UP

try to ping an address in your LAN ( another VM, or the gateway )
 
Hello manu, i have a monitoring system (PRTG) from somewhere else. So i know exactly when the problem exist.
I will check ip --color link it when it happen again.
when i ping to a website inside the vm, 2 seconds later (like waking up from sleep modus) ping replys good.

For this moment, I made a backup and restore from the server. For trying.
 
I made 8-2-2017 a backup and restore. 1 day everything went well, but today 2 VM's (on different physical servers) had the same problem.
The vm's were 5 - 20 minutes 'offline' from outside (ping with PRTG). 1 vm server is a production server, so i must fix this problem :(
I was to late behind my pc for checking above options.

so, for now i disabled the proxmox firewall at datacenter level now and waiting if it goes better / good.
:( :( :(
when the problem is : proxmox firewall, i will use again the firewalls from ubuntu VM's.

update: till now (10-02-2017 7:23 AM) no problems. I will wait till the end of this day. fingers crossed.
But if proxmox firewall is a problem.. who could help me?
 
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I will open in short minutes a new thread, why other has equal problems with KVM and exists as other threads! This is very interessting about KVM and routing and firewall - block expl. diferent KVM-machines to communicate from inside to outside!
 
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