4Network Assurance

• 4.1Diagnostic tools (debug, ping, traceroute, SNMP, syslog)

  Covers debug and the CPU-friendly conditional debug, ping for L3 reachability (extended ping with source/size/df-bit), traceroute for seeing where a path stops, SNMP for collecting device state by polling and notification, and syslog with severity design--all framed as the isolation judgment of "which tool confirms what, without overloading a production device."

• 4.2Traffic visibility and measurement (NetFlow, SPAN, IP SLA)

  Covers Flexible NetFlow for aggregating "who talked to whom and how much" (define a flow record, flow exporter, and flow monitor, then apply it to an interface), packet-copying with SPAN (same device), RSPAN (via a VLAN), and ERSPAN (across L3 using GRE), and IP SLA for actively measuring reachability, latency, and jitter with synthetic traffic and switching paths through object tracking--framed as the selection judgment of "which measurement confirms this symptom."

• 4.3Controllers and programmable management (Catalyst Center, NETCONF, RESTCONF)

  Covers the four intent-based workflows of Cisco Catalyst Center (formerly DNA Center) with Assurance and its AI/machine-learning anomaly detection, NETCONF which writes XML over SSH port 830 into a candidate datastore and applies it atomically with commit, and RESTCONF which maps CRUD onto HTTP methods with JSON--framed as the selection judgment of "which mechanism safely delivers this change."