Upgrading the primary to protocol version 1

You can now upgrade the replica set protocol version to pv1:

1. Use the mongo (https://docs.mongodb.com/manual/mongo/#the-mongo-shell) shell to connect to the primary in the replica set:

 mongo --host <address of primary>

2. Once connected to the primary, run these commands to update the protocol version for the replica set:

cfg = rs.conf();
 cfg.protocolVersion=1;
 rs.reconfig(cfg);