The error "ElastiCache network bandwidth in allowance exceeded" typically occurs when the amount of data transfer or network traffic between your ElastiCache cluster and its clients surpasses the allowed limits set by AWS. This can be caused by a sudden increase in client requests, inefficient cache usage patterns, or an improperly configured ElastiCache cluster. Additionally, it could also be due to data-heavy operations like snapshots, backups, and replication, which consume significant bandwidth.
To resolve this error, you should first analyze the traffic patterns and determine the cause of the excessive network usage. Optimize your cache usage by reviewing the efficiency of your data retrieval methods, such as using pipelining for multiple requests or consolidating data. Ensure that cache keys are appropriately sized and structured. If needed, consider upgrading your ElastiCache instance type to one with higher network performance capabilities. For data-heavy operations, schedule them during off-peak hours to minimize impact on network bandwidth. Finally, monitor your network usage regularly using tools like AWS CloudWatch to proactively identify and address any potential issues before they exceed the allowed bandwidth.