1) Install controller
2) Enable features
feature:install odl-l2switch-all
feature:install odl-l2switch-switch-rest

3) Connect a mininet switch with 400+ hosts connected.
4) Do one round of ping between the hosts. (ping with -c 1 option)
5) Pings are successful.
6) Make REST call and count the hosts.
7) Not all hosts are learned.
8) This is happening only at scale of 400+.
9) The test is automated and the result is available below link
https://jenkins.opendaylight.org/releng/job/l2switch-csit-periodic-1node-cds-host-scalability-daily-only-master/plot/Inventory%20Host%20Scalability/

10) This behavior is noticed with Helium too.