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INCIDENT #192 · BGP

Backup network: The service edge stops exchanging BGP routes

Medium25 minutesPro lab

The incident

Backup agents traverse a routed storage boundary while replication monitoring and a lab tenant share a separate branch. Two distribution routers carry separate client, partner, monitoring and service branches. Direct uplink connectivity works, but remote routers no longer learn either service prefix from the service edge. Investigate backup transport from R1: 10.174.224.0/24 to 10.174.230.0/24 (TCP/2049), and 10.174.225.0/24 to 10.174.231.0/24 (UDP/111).

Your objective

Restore both authorized service transports and return reachability, including clients and service hosts in both halves of the primary subnet. Keep R5 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R1 and R6. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.

The network

Network topology6 devices 5 links

Backup network: The service edge stops exchanging BGP routes — network topologyR1: Client edge. R2: West distribution. R3: East distribution. R4: Service gateway. R5: Partner edge. R6: Monitoring edge. R1 connects to R2. R2 connects to R3. R3 connects to R4. R2 connects to R5. R3 connects to R6. Connections show physical links, not service health.R1 ↔ R2 · 10.174.240.0/30R2 ↔ R3 · 10.174.241.0/30R3 ↔ R4 · 10.174.242.0/30R2 ↔ R5 · 10.174.243.0/30R3 ↔ R6 · 10.174.244.0/30R1Client edgeR1 · Client edge · Starting deviceR2WestdistributionR2 · West distributionR3EastdistributionR3 · East distributionR4ServicegatewayR4 · Service gatewayR5Partner edgeR5 · Partner edgeR6MonitoringedgeR6 · Monitoring edge
Physical links · Service health not shown
6 devices · Cisco IOS syntax · Simulated network

What you’ll practice

ebgppeer as validationroute exchange

Interview exercises are inspired by common industry competencies. They are not proprietary interview questions.