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INCIDENT #044 · BGP

A healthy but empty peer

Expert35 minutesPro lab

The incident

Albuquerque edge. The partner network branches off near ingress while the service sits three transport hops farther away. Clients cannot reach the primary service. Restoring its BGP advertisement still leaves replies to one client address failing. Investigate the two service networks from R1: 10.206.128.0/24 to 10.206.136.0/24 (TCP/443), and 10.206.129.0/24 to 10.206.137.0/24 (TCP/8443).

Your objective

Restore both authorized service transports and return reachability, including clients and service hosts in both halves of the primary subnet. Keep R6 blocked from both service transports, keep SSH blocked to both service subnets, and preserve monitoring between R1 and R4. Do not change physical topology or addressing. These are network forwarding checks, not application-level transactions.

The network

Network topology6 devices 5 links

A healthy but empty peer — network topologyR1: Client edge. R2: Ingress hub. R3: WAN transit. R4: Service handoff. R5: Service gateway. R6: Partner edge. R1 connects to R2. R2 connects to R3. R3 connects to R4. R4 connects to R5. R2 connects to R6. Connections show physical links, not service health.R1 ↔ R2 · 10.206.144.0/30R2 ↔ R3 · 10.206.145.0/30R3 ↔ R4 · 10.206.146.0/30R4 ↔ R5 · 10.206.147.0/30R2 ↔ R6 · 10.206.148.0/30R1Client edgeR1 · Client edge · Starting deviceR2Ingress hubR2 · Ingress hubR3WAN transitR3 · WAN transitR4ServicehandoffR4 · Service handoffR5ServicegatewayR5 · Service gatewayR6Partner edgeR6 · Partner edge
Physical links · Service health not shown
Link addressing (5)
  • R1 R210.206.144.0/30
  • R2 R310.206.145.0/30
  • R3 R410.206.146.0/30
  • R4 R510.206.147.0/30
  • R2 R610.206.148.0/30
6 devices · Cisco IOS syntax · Simulated network

What you’ll practice

bgp originationreturn pathcompound failures

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