I have an IP on interface ens160 ( 10.209.70.147 ) which is up and responding to traffic. Then I add another interface eth0 in "connected state" from vmware console and add another IP ( 10.209.226.248) in netplan to eth0. When I do a netplan apply I see that IP in ens160 goes down temporarily. systemd also confirms it:-
Aug 21 17:56:39 10 kernel: [3542843.809266] vmxnet3 0000:03:00.0 ens160: intr type 3, mode 0, 3 vectors allocated
Aug 21 17:56:39 10 kernel: [3542843.809833] vmxnet3 0000:03:00.0 ens160: NIC Link is Up 10000 Mbps
Aug 21 17:56:39 10 systemd-networkd[307]: ens160: Lost carrier
Aug 21 17:56:39 10 systemd-networkd[307]: ens160: Link UP
Aug 21 17:56:40 10 systemd-networkd[307]: ens160: Gained carrier
Aug 21 17:56:41 10 ntpd[607]: Listen normally on 28 ens160 10.209.226.248:123
TCP dump also shows packet loss on 10.209.70.147:-
78194 2023-08-21 17:56:40.457615 0.307371 10.49.24.148 10.209.70.149 TCP 1356 [TCP Retransmission] 59675 → 9090 [PSH, ACK] Seq=197416 Ack=139625 Win=262144 Len=1300
78278 2023-08-21 17:56:41.061066 0.603451 10.49.24.148 10.209.70.149 TCP 1356 [TCP Retransmission] 59675 → 9090 [PSH, ACK] Seq=197416 Ack=139625 Win=262144 Len=1300
78195 2023-08-21 17:56:40.477066 0.000000 10.49.24.148 10.209.70.147 TCP 68 59873 → 443 [SYN] Seq=0 Win=64896 Len=0 MSS=1352 WS=256 SACK_PERM=1
80105 2023-08-21 17:56:41.490827 1.013761 10.49.24.148 10.209.70.147 TCP 68 [TCP Retransmission] 59873 → 443 [SYN] Seq=0 Win=64896 Len=0 MSS=1352 WS=256 SACK_PERM=1
This packet loss causes traffic to go down for couple of seconds. This is happening on Ubuntu 20.04. Haven't checked on higher versions. Is it a known issue on Ubuntu 20.04? Can not netplan apply behaviour be made smooth without making the interface go down temporarily? Any leads will be helpfull.