We had a node that could not connect to indy network due to zmq.Again errors.

[KimEbert42]

We had a node that could not connect to the indy network. We saw the message in the log file on the node it was trying to connect to

aaaaaa could not transmit message to bbbbbb

This message kept repeating.

This appears to be due to a zmq.Again error.

This indicates that zmq PAIR connections may not recover from networking errors.

https://stackoverflow.com/questions/49222514/recovering-from-zmq-error-again-on-a-zmq-pair-socket

We only log a message on error, which will not recover the TCP connection

https://github.com/hyperledger/indy-plenum/blob/main/stp_zmq/zstack.py#L865

A work around is to restart the node that has displayed the message and the node attempting to connect will be able to connect.