systemd LACP bond mess up aggregation ID for NICs

arch linux with lts kernel systemd networkd is configured to bond two NICs into LACP trunk with smart switch (DGS-1210-28). But it fails after OS startup - only one NIC is used for bond connection. As shown in /proc/net/bonding/* Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011) Bonding Mode: IEEE 802.3ad Dynamic link aggregation Transmit Hash Policy: layer3+4 (1) MII Status: up MII Polling Interval (ms): 1000 Up Delay (ms): 0 Down Delay (ms): 0 802.3ad info LACP rate: slow Min links: 0 Aggregator selection policy (ad_select): stable System priority: 65535 System MAC address: **:**:**:**:**:ad Active Aggregator Info: Aggregator ID: 2 Number of ports: 1 Actor Key: 9 Partner Key: 3 Partner Mac Address: **:**:**:**:**:6e Slave Interface: enp7s0 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: **:**:**:**:**:67 Slave queue ID: 0 Aggregator ID: 1 Actor Churn State: churned Partner Churn State: churned Actor Churned Count: 1 Partner Churned Count: 1 details actor lacp pdu: system priority: 65535 system mac address: **:**:**:**:**:ad port key: 0 port priority: 255 port number: 1 port state: 69 details partner lacp pdu: system priority: 65535 system mac address: 00:00:00:00:00:00 oper key: 1 port priority: 255 port number: 1 port state: 1 Slave Interface: enp2s0 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 1 Permanent HW addr: **:**:**:**:**:ef Slave queue ID: 0 Aggregator ID: 2 Actor Churn State: none Partner Churn State: none Actor Churned Count: 0 Partner Churned Count: 0 details actor lacp pdu: system priority: 65535 system mac address: **:**:**:**:**:ad port key: 9 port priority: 255 port number: 2 port state: 61 details partner lacp pdu: system priority: 32768 system mac address: **:**:**:**:**:6e oper key: 3 port priority: 128 port number: 15 port state: 61 notice that bond have AggregatorID=2, and unused (churned) NIC have AggregatorID=1, which is weird. I'd expect bond to have AggregatorID=1 This can be "fixed" by physical port reconnect for churned NIC. After this both NICs are used by bond. This can be seen in kernel log: >> OS startup >> churned NIC physical disconnect >> churned NIC physical connect notice that NIC "enp7s0" initialized first, but gets churned. Config files: enp-any.network [Match] Name=enp* [Network] Bond=Trunk0 Trunk0.netdev [NetDev] Name=Trunk0 Kind=bond [Bond] Mode=802.3ad TransmitHashPolicy=layer3+4 MIIMonitorSec=1s LACPTransmitRate=slow Trunk0.network [Match] Name=Trunk0 [Network] VLAN=*** VLAN=*** VLAN=*** LinkLocalAddressing=no BindCarrier=enp2s0 enp7s0