Sessions Expire due to Network partitioning in Zookeeper

Recently, carried out a test to to find the behavior of clients when a zookeeper server is isolated from the zookeeper leader.

Here used a ensemble of 3 zookeeper servers called A, B and C. And quorum was set up like below.

A - Follower
B - Leader
C - Follower​

A <==> B <==> C
I____________I

And 3 clients are connected to ensemble like below.

C1 is connected A. Both C1 and A are in the same machine.
C2 is connected B. Both C2 and B are in the same machine.
C3 is connected C. Both C3 and C are in the same machine.

To remove the network link between B and C iptables utility is used.

command used:
iptables -I INPUT -s Server_B_IP -j DROP
iptables -I INPUT -s Server_C_IP -j DROP

After removing the link connections looks like below.

A <===> B C
I________I

Simply there is no way to send any packets from zookeeper server B to zookeeper server C and vice versa. But the connection exists between between B and C. And also there is no way to send any packets from B to C3 and vice versa. But the connection exists between between B and C3.

Here What I noticed is that the client connected to Zookeeper Server "C", could not connect to the ensemble, resulting a session expiration timeout.

For this experiment I used tickTime of 3000ms and client session expiration timeout of 45000ms. And tested with different combinations also.