to a small maintenance window) and accurately (by not affecting any existing setting) is key. Upgrading a mid-sized network (with physical functions varying from hundreds to thousands) within a maintenance window of a few hours is a mammoth task. Hence, automation saves the day. Configuration updates and health checks after the application of changes via automation are getting extremely popular; also, the rollback option is scripted. Hence, if anything was to go wrong, the script would automatically roll back with minimal or no human intervention. Similarly, for upgrades, pre- and post-checks can be automated, and similar rollback options can be added in case the upgrade hits a roadblock. Automation, Orchestration, and Testing The following figure depicts broad areas of network automation: Network Automation Deployment Testing Operations Automation Operation Automation Physical Lab Testing Configuration Functions Changes Virtual Pre-Production Software Functions Testing Upgrades Cloud-Native Production Hardware Functions Testing Replacements Service Observability Orchestration Network Audits Reporting Figure 17.2 - Network automation areas Testing: Testing is one of the most essential aspects of network design. This includes the functional testing of the individual network elements, which could be physical, virtual, or cloud-native. Testing areas also include the integration validation of all the network elements (whether they can communicate with each other and are tuned in terms of latency, timers, and other inter-dependent configurations), and then testing end-to-end call flows of various types, which would test the overall functioning of the various network functions making the network. For a network, all the expected use cases that it is designed to support must be tested in detail. This should also include border and edge cases and failure testing. This would help to understand the limits of the network and its performance during a network component failure. Another important aspect of the test is to evalua