[PVE-User] pve-user Digest, Vol 64, Issue 25

Martin Schuchmann ms at city-pc.de
Sun Jul 28 19:13:04 CEST 2013

schrieb pve-user-request at pve.proxmox.com:
> i have been running a private cloud for about a year, although i am using PVE for 4 years but this is first time i am using it for remote cloud.
> every thing is working great and nothing happen for about a year. however i observe one issue. which is Virtual Machine lan card related,
> this is not happening very frequently . but happen once in a 3 month and not on all machines but few machines.
> the problem is, VM stop reaching the LAN and WAN.
> when i ping , it says "destination host unreachable"

We had a similar problem in a datacenter: We startet to ping the switch 
to whom the physical network interface is connected via cronjob - and 
the problem disappears. The datacenter maintainer told us, that there 
could be a problem with the ARP table in the switch, when connecting 
different (virtual) MAC Adresses over different VLANs on the same cable 
- if there is no traffic on some of them, it may loose the cached older 
MACs and does not check for new ones, because he has already an amount 
of active MACs on this line.

There should be no problem with that, but obviously it was exactly the 
problem - and according to your case, it could be the same, as you told 
to run a private cloud for years before without that behaviour. We 
experienced this only on one networkinterface  - at other servers with 
other LAN cards, it works properly all the time.

It is just a workaround, but myabe the solution could be only found in 
the switch firmware...

Many regards,


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