bidirectionnal connection fro merge replication?

Hello, I only need to know if I need to have a bidirectionnal connection between the subscriber and the publisher for merge replication or if the connection ca be openned only from the publisher to the subscriber if i use the push subscription option.
Thanks in advanceIn a push merge replication scenario you still need to ensure that there is a communication going when new transactions are posted on the subscriber(-s)'s side.