CloudMonitor helps you monitor the usage of NAT Gateway by monitoring the number of SNAT connections of the NAT gateway and so on. You can also set alarm rules for the monitored items. For more information, see NAT gateway monitoring.
You can also monitor the inbound bandwidth, outbound bandwidth, per-second incoming packet count, and per-second outgoing packet count of each EIP bound to the NAT gateway at any time on CloudMonitor. For more information, see EIP monitoring.