With "drop the newtork" I mean that both ping and SSH toward the guests
throw a "Destination Host Unreachable".
When the network drops, running `ifconfig` from inside the guests keeps
showing the same, correct data as before the drop, like IP address, MAC
and netmask. But after the ethernet cable is unplugged and re-plugged
causing a drop, the guests may no longer be reached via SSH nor ping-ed,
and vice versa, the guests may not reach any virtual or physical host in
the network, yielding a "Destination Host Unreachable".
A ping toward "localhost" from inside the guests works correctly, as
well as SSH.
My network configuration has nothing peculiar; I have no NAT or firewall
configured anywhere in my network, except for a few unrelated port
forwards set on the home ADSL modem/router, but they do not apply since
all accesses to my guest machines are made via their local IP addresses
(ie 192.168.1.100), and so those NAT rules are bypassed. In this
consumer-grade modem/router, NAT rules are applied only to packets
coming from internet and not to packets coming from the local network,
and I'm connecting to the guests from inside the local network.
I'm not involved at all with settings pertaining layer 2 or layer X of
the network.
-- Davide
On 08/24/2015 08:29 PM, Tony Su wrote:
Consider whether you're talking about layer 2 or layer 3 network
connectivity (test).
If this is a Workgroup, consider whether you have a Browse Master issue.
Consider whether your issue is a name resolution issue.
I assume the connection is bridged? Try NAT if it doesn't make a diff to you.
Tony
On Mon, Aug 24, 2015 at 7:29 AM, Vlad Yasevich <vyase...@redhat.com> wrote:
On 08/23/2015 07:31 AM, Davide Baldini wrote:
Thanks Vlad,
.. snip..
As far as I notice, there are no differences shown by `ifconfig`.
The fact is, that all guests drop the network after a cable is unplugged and
then
replugged, while the host's network keeps functioning.
What do you mean by "drop network"? Is the link going down in the guest? Is
the guest losing IP address? Is the guest simply stops being reachable?
Are there any firewall rules on the host?
Thanks
-vlad
Where else can I look?
-- Davide
On 08/19/2015 08:02 PM, Vlad Yasevich wrote:
On 08/16/2015 12:55 PM, Davide Baldini wrote:
When I unplug the ethernet cable from the physical host, guest fails to
reconnect; host
does reconnect.
What do you mean by 'reconnect'? Unplugging the cable for the nic on the
physical host
does not really disconnect the guest from the network. According to the
configuration
your provided, the guest is still connected to the bridge on the host and can
still
communicate with other guests on the same host.
Once the host network is plugged back in, the bridge should start forwarding
packets
back to the guest.
A very simple configuration here, with an almost default Debian 7 on both host
and guest:
-- ON HOST:
/etc/network/interfaces
auto lo
iface lo inet loopback
auto br0
iface br0 inet dhcp
bridge_ports eth1
bridge_stp off
bridge_maxwait 0
bridge_fd 0
-- ON GUEST:
/etc/network/interfaces
auto eth0
allow-hotplug eth0
iface eth0 inet static
address 192.168.1.109
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
dns-nameservers 192.168.1.1
QEMU is started as:
/usr/local/bin/qemu-system-x86_64 -hda /media/raid1/qemu-109 -m 8G -smp 4
-enable-kvm
-netdev bridge,id=br109 -device
virtio-net-pci,netdev=br109,id=nic0,mac=00:00:00:00:01:09
-k it -daemonize
QEMU emulator version 2.3.0
Nothing appears on dmesg. Any hints?
Make sure that the bridge on the host is formed correctly after the cable has
been plugged
back in.
-vlad
-- Davide