For troubleshooting, or just generally seeing what's going on, we can use

• LLDP (Link Layer Discovery Protocol)
• CDP (Cisco Discovery Protocol)
• IP Scanners (nmap)
• Network Scanners
• SNMP

We can run scans as needed or we can schedule them

Traffic analysis - View traffic information from network devices such as routers, switches, firewalls, etc.

• Identify traffic flows and view summaries
• Can collect over a long period of time for reports or forensics

Performance Monitoring We can gather key performance metrics using SNMP, NetFlow, protocol analysis (WireShark), or software agents

Availability Monitoring - Is a device up or down

• Can be used with alerts to send an alert when a device goes does

Configuration Monitoring - Allows us to monitor the configurations of a number of devices to ensure that they are consistent.

• Often part of a larger management system where alerts can be sent if a configuration changes and backups can be deployed