Comment 3 for bug 1727301

the networking is configured via systemd-networkd.
bonding module is loaded with 'max_bonds=0' to address upcoming systemd change
https://github.com/systemd/systemd/issues/6184

pre-upgrade:

# networkctl
IDX LINK TYPE OPERATIONAL SETUP
  1 lo loopback carrier unmanaged
  2 eth0 ether carrier configuring
  3 eth1 ether carrier configuring
  4 bond0 ether routable configured
  5 bond0.200 ether routable configured

# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
4: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
5: bond0.200@bond0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff

interfaces(.d) and netplan are empty and unused/disabled

/etc/systemd/network:

# cat eth1.network
[Match]
Name=eth1

[Network]
Bond=bond0

# cat eth0.network
[Match]
Name=eth0

[Network]
Bond=bond0

# cat bond0.netdev
[NetDev]
Name=bond0
Kind=bond

[Bond]
Mode=802.3ad
MIIMonitorSec=0.1s
LACPTransmitRate=fast
UpDelaySec=0.2s
DownDelaySec=0.2s

# cat bond0.network
[Match]
Name=bond0

[Address]
Address=192.168.1.100/24

[Route]
Gateway=192.168.1.1

[Network]
VLAN=bond0.200

[Link]
MTUBytes=9000

# cat bond0.200.netdev
[NetDev]
Name=bond0.200
Kind=vlan

[VLAN]
Id=200

# cat bond0.200.network
[Match]
Name=bond0.200

[Address]
Address=10.10.0.100/16

[Route]
Gateway=10.10.0.1

[Link]
MTUBytes=9000

After upgrade:

# networkctl
IDX LINK TYPE OPERATIONAL SETUP
  1 lo loopback carrier unmanaged
  2 eth0 ether carrier configuring
  3 eth1 ether carrier configuring
  4 bond0 ether routable configured
  5 bond0.200 ether routable configured

However, the link of eth0, eth1 and the bond and vlan interface changes to NOARP

# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,NOARP,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,NOARP,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
4: bond0: <BROADCAST,MULTICAST,NOARP,MASTER,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff
5: bond0.200@bond0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 5a:42:ff:c5:26:61 brd ff:ff:ff:ff:ff:ff