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Capstone Network Configuration Lab

Summary​

Configured a multi-network environment with routing, DHCP, and OSPF to allow communication between IT & Security, Sales, and Admin networks. Worked through several interface and neighbor formation issues before achieving full connectivity.

Notes​

Network Overview​

NetworkSubnetGateway
IT & Security10.1.1.0/2610.1.1.1
Sales10.1.1.96/2810.1.1.97
Admin10.1.1.112/2810.1.1.113

WAN Links:

  • Sales ↔ Admin: 10.1.1.248/30
  • Admin ↔ IT: 10.1.1.252/30

Device Configuration​

ITSecurityRouter​

Interfaces:

  • G1/0 → 10.1.1.1/26 (LAN)
  • G2/0 → 10.1.1.254/30 (to Admin)

DHCP Relay:

ip helper-address 10.1.1.113

Routing: Static default route → 10.1.1.253

OSPF networks:

  • 10.1.1.0/26
  • 10.1.1.252/30

AdminRouter​

Interfaces:

  • G0/0 → 10.1.1.250/30 (to Sales)
  • G2/0 → 10.1.1.253/30 (to IT)
  • G3/0 → 10.1.1.113/28 (LAN)

DHCP Pool — Admin:

  • Network: 10.1.1.112/28
  • Gateway: 10.1.1.113
  • DNS: 10.1.1.115

OSPF networks:

  • 10.1.1.112/28
  • 10.1.1.248/30
  • 10.1.1.252/30

SalesRouter​

Interfaces:

  • G0/0 → 10.1.1.97/28 (LAN)
  • G0/1 → 10.1.1.249/30 (to Admin)

DHCP Pool — Sales:

  • Network: 10.1.1.96/28
  • Gateway: 10.1.1.97

OSPF networks:

  • 10.1.1.96/28
  • 10.1.1.248/30

Issues Encountered​

1. OSPF Neighbor Not Forming​

  • Symptom: ITSecurityRouter had no OSPF neighbors
  • Cause: Admin ↔ IT link misconfigured and moved to fiber interface
  • Fix:
    • Assigned IPs to G2/0 on both routers
    • Reconnected correct interfaces
    • Reset OSPF process

2. No Route to Admin Network​

  • Symptom: IT router could not reach 10.1.1.115
  • Cause: Admin LAN interface GigabitEthernet1/0 was down/down
  • Fix:
    • Enabled interface with no shutdown
    • Verified physical connection to switch

3. Incorrect Interface Assignment​

  • Symptom: Admin LAN assigned to wrong interface (G1/0 vs G3/0)
  • Cause: Switch connected to incorrect port
  • Fix:
    • Moved Admin LAN to G3/0
    • Connected switch to G3/0
    • Removed IP from incorrect interface

4. Initial Packet Loss​

  • Symptom: First ping had 80% success rate
  • Cause: ARP resolution delay
  • Result: Subsequent pings successful

Verification​

OSPF Neighbor: IT ↔ Admin adjacency established (FULL state)

Routing Table (ITSecurityRouter):

O 10.1.1.96/28  (Sales)
O 10.1.1.112/28 (Admin)

Connectivity Tests — all successful:

  • 10.1.1.113 (Admin Gateway)
  • 10.1.1.115 (Server)

DHCP: Clients received correct IP addresses in each subnet.

Insights​

The most important lesson from this lab was that interface assignment errors are easy to make and hard to spot without methodically verifying each connection. Checking show ip int br at each step would have caught the down/down interface much earlier. The ARP delay on the first ping is also worth remembering — a single failed ping doesn't always mean routing is broken.

OSPF neighbor formation is sensitive to interface configuration. When neighbors won't form, the first step is always to verify that the connecting interfaces have matching subnet IPs and are actually up/up.

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