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INCIDENT #041 · BGP

Peering after the migration

Medium25 minutesPro lab

The incident

Minneapolis edge. Four routed metro nodes form a ring; the service gateway has a separate handoff. Direct uplink connectivity works, but remote routers no longer learn either service prefix from the service edge. Investigate the two service networks from R2: 10.206.34.0/24 to 10.206.40.0/24 (TCP/443), and 10.206.35.0/24 to 10.206.41.0/24 (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 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

Network topology5 devices 5 links

Peering after the migration — network topologyR1: West metro. R2: Client metro. R3: South metro. R4: East metro. R5: Service gateway. R1 connects to R2. R2 connects to R3. R3 connects to R4. R4 connects to R1. R4 connects to R5. Connections show physical links, not service health.R1 ↔ R2 · 10.206.48.0/30R2 ↔ R3 · 10.206.49.0/30R3 ↔ R4 · 10.206.50.0/30R4 ↔ R1 · 10.206.51.0/30R4 ↔ R5 · 10.206.52.0/30R1West metroR1 · West metroR2Client metroR2 · Client metro · Starting deviceR3South metroR3 · South metroR4East metroR4 · East metroR5ServicegatewayR5 · Service gateway
Physical links · Service health not shown
Link addressing (5)
  • R1 R210.206.48.0/30
  • R2 R310.206.49.0/30
  • R3 R410.206.50.0/30
  • R4 R110.206.51.0/30
  • R4 R510.206.52.0/30
5 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.