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IPV6 conflict VM Ubuntu 20.04 - Netplan

Irkoska

11/29/23, 8:57 PM

I have a problem, I've two virtual machines, but the problem is that when I turn on the second VM I lost the connection on the first one and vice versa.

Here is the bridge netplan configuration on the host server :

network:
  version: 2
  renderer: networkd
  ethernets:
    enp1s0f0:
      dhcp4: no
      dhcp6: no
  bridges:
    viifbr0:
      addresses:
        - 135.xxx.159.xx/24
        - 2001:xxxx:xxx:500f::/128
      interfaces: [ enp1s0f0 ]
      routes:
        - on-link: true
          to: 0.0.0.0/0
          via: 135.xxx.159.xxx
        - on-link: true
          to: ::0/
          via: 2001:xxxx:xxx:50ff:ff:ff:ff:ff
      gateway6: 2001:xxxx:xxx:50ff:ff:ff:ff:ff
      macaddress: xx:40:xx:fe:xx:7b
      nameservers:
         addresses:
           - 8.8.8.8
           - 8.8.4.4
           - 2001:4860:4860::8888
           - 2001:4860:4860::8844

(IPv6 Forwarding is enabled)

Here is the client network configuration :

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet6 static
        accept_ra 0
        address 2001:xxxx:xxx:500f::a2
        netmask 64


post-up /sbin/ip -r route add 2001:xxxx:xxx:50ff:ff:ff:ff:ff dev eth0
post-up /sbin/ip -r route add default via 2001:xxxx:xxx:50ff:ff:ff:ff:ff

Can you help me ?

Thank you.

Regards, Irkoska

185

1 + 6

ubuntu

virtual-machines

bridge

netplan

vidarlo

11/29/23, 9:01 PM

No, based on a very vague description and no configuration of the clients, we can't help you. How is the clients configured? Do you have RA functioning, or are you running static assignments?

Irkoska

11/29/23, 9:10 PM

Thank you @vidarlo for your quick reply, I edited the topic to add the client configuration. The configuration is the same on both virtual machines.

vidarlo

11/29/23, 9:13 PM

Both run with the same IP? In the same subnet?

Irkoska

11/29/23, 9:33 PM

All VM have a different IPv6 but the gateway is the same (2001:xxxx:xxx:50ff:ff:ff:ff:ff)

Gerald Schneider

11/30/23, 6:22 AM

Do these two VMs by chance have the same MAC address (maybe because one is a clone of the other)?

Irkoska

11/30/23, 1:38 PM

Oooooh my goodness was that the hypervisor had assigned the same mac address on the machines. Thank you @GeraldSchneider. Now I must find why my virtual machines are not reachable.

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Gerald Schneider

11/30/23, 2:39 PM

Make sure the VMs have different MAC addresses. An external DHCP server would not be able to distinguish them with the same MAC address and would assign both the same IP address.

+ 1

Irkoska

11/30/23, 2:44 PM

Yes of course, the hypervisor had assigned the same mac address on the virtual machines. Thank you. Now I must find why my virtual machines are not reachable.

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