Summing UP all Above comments:
----------------------------

Ubuntu:
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic


this scenario is: i need to create 1000 of virtual interface , this is scale environment, where each new interface causing restart of networkd-dispatcher, losing out on older interface, if there creation is not completed successfully.
 

-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------
Operation:
create 2 virtual interface of mac vlan type, as 2icx0, 2icx1,
always the last created interface is availble, older one get deleted due to

Apr 16 10:56:28 u18_svr_madsz networkd-<wbr>dispatcher[<wbr>824]: WARNING:Unknown index 72 seen, reloading interface list
Apr 16 10:56:28 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx0: Lost carrier

Same feature macvlan work in 16.04

<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------

 

problem occurs when both interface created using multiprocessing module of python
----------------
Process 1 execution ->
ip link add link ens34 2icx0 type macvlan
ifconfig 2icx0 up
ip addr add 192.168.49.230/16 dev 2icx0

Process 2 execution ->
ip link add link ens34 2icx1 type macvlan
ifconfig 2icx1 up
ip addr add 192.168.49.231/16 dev 2icx1

----------------

however this works when run in a order like:
-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-------<wbr>-
ip link add link ens34 2icx0 type macvlan
ifconfig 2icx0 up
ip addr add 192.168.49.230/16 dev 2icx0
ip link add link ens34 2icx1 type macvlan
ifconfig 2icx1 up
ip addr add 192.168.49.231/16 dev 2icx1
 

 

 

 

Failed Logs:
------
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>udevd[30948]<wbr>: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>udevd[30948]<wbr>: Could not generate persistent MAC address for 2icx0: No such file or directory
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx0: Gained carrier
Apr 16 10:56:27 u18_svr_madsz networkd-<wbr>dispatcher[<wbr>824]: WARNING:Unknown index 71 seen, reloading interface list
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>timesyncd[<wbr>22214]: Network configuration changed, trying to establish connection.
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>udevd[30960]<wbr>: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Apr 16 10:56:27 u18_svr_madsz systemd-<wbr>udevd[30960]<wbr>: Could not generate persistent MAC address for 2icx1: No such file or directory
Apr 16 10:56:28 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx1: Gained carrier
Apr 16 10:56:28 u18_svr_madsz networkd-<wbr>dispatcher[<wbr>824]: WARNING:Unknown index 72 seen, reloading interface list
Apr 16 10:56:28 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx0: Lost carrier
Apr 16 10:56:28 u18_svr_madsz systemd-<wbr>timesyncd[<wbr>22214]: Synchronized to time server 91.189.89.199:123 (ntp.ubuntu.com).
Apr 16 10:56:29 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx1: Gained IPv6LL

Successful Logs:
------
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>udevd[31348]<wbr>: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx0: Gained carrier
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>timesyncd[<wbr>22214]: Network configuration changed, trying to establish connection.
Apr 16 12:10:38 u18_svr_madsz networkd-<wbr>dispatcher[<wbr>824]: WARNING:Unknown index 75 seen, reloading interface list
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>udevd[31348]<wbr>: Could not generate persistent MAC address for 2icx0: No such file or directory
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>udevd[31358]<wbr>: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>udevd[31358]<wbr>: Could not generate persistent MAC address for 2icx1: No such file or directory
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx1: Gained carrier
Apr 16 12:10:38 u18_svr_madsz networkd-<wbr>dispatcher[<wbr>824]: WARNING:Unknown index 76 seen, reloading interface list
Apr 16 12:10:38 u18_svr_madsz systemd-<wbr>timesyncd[<wbr>22214]: Synchronized to time server 91.189.91.157:123 (ntp.ubuntu.com).
Apr 16 12:10:39 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx0: Gained IPv6LL
Apr 16 12:10:40 u18_svr_madsz systemd-<wbr>networkd[<wbr>22168]: 2icx1: Gained IPv6LL