The network is reliable
Service calls made over the network might fail. There can be congestion in network or power failure impacting your systems. The request might reach the destination service but it might fail to send the response back to the primary service. The data might get corrupted or lost during transmission over the wire. While architecting distributed cloud applications, you should assume that these type of network failures will happen and design your applications for resiliency.
To handle this scenario, you should implement automatic retries in your code when such a network error occurs. Say one of your services is not able to establish a connection because of a network issue, you can implement retry logic to automatically re-establish the connection.
There are some very good points in here.