Correlate the control plane and the forwarding path.
Move from knowing protocol vocabulary to diagnosing a fault across multiple views of the network.
Compare tables with behavior
A learned route, selected route, and working service are different observations. Use a packet trace to connect them.
Keep the boundaries intact
A repair that restores an application by removing all filters changes the security policy. Verify both the allowed and forbidden flows.
Practice under constraints
Investigate before editing, use minimal changes, and record why the remediation follows from your observations. These are independent exercises, not an official Cisco exam simulator.
Green links. Broken checkout.
Chicago payments network. Four routed metro nodes form a ring; the service gateway has a separate handoff. Route checks and ICMP succeed. The primary service transport fails even though an allow rule appears in the service access list. Investigate the two service networks from R2: 10.201.130.0/24 to 10.201.136.0/24 (TCP/443), and 10.201.131.0/24 to 10.201.137.0/24 (TCP/8443).
Link addressing (5)
- R1 R2
10.201.144.0/30 - R2 R3
10.201.145.0/30 - R3 R4
10.201.146.0/30 - R4 R1
10.201.147.0/30 - R4 R5
10.201.148.0/30
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