Industrial campus: A new service prefix never reaches clients
The incident
Engineering stations reach plant service gateways through the site core and two production aggregation layers. Four routed metro nodes form a ring; the service gateway has a separate handoff. BGP carries the primary service prefix, but the connected secondary service subnet is absent from remote BGP tables. Investigate plant gateway transport from R2: 10.177.130.0/24 to 10.177.136.0/24 (TCP/502), and 10.177.131.0/24 to 10.177.137.0/24 (TCP/4840).
Your objective
Restore both authorized service transports and return reachability, including clients and service hosts in both halves of the primary subnet. Keep R3 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R2 and R1. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.
The network
Link addressing (5)
- R1 R2
10.177.144.0/30 - R2 R3
10.177.145.0/30 - R3 R4
10.177.146.0/30 - R4 R1
10.177.147.0/30 - R4 R5
10.177.148.0/30
What you’ll practice
Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.