Why this step matters
Before configuring anything, you must know:
- which interface is LAN
- which is WAN
- which goes upstream / downstream
This prevents 90% of CCNA mistakes.
🔹 11.1 Head Office Router — HO-R1
Open HO-R1 → CLI and just look, don’t configure:
show ip interface brief
Conceptual role of interfaces:
- GigabitEthernet0/0 → LAN side (to DIST-SW1)
- Serial0/x/x → WAN side (to BR-R2)
- GigabitEthernet0/1 (if connected to ISP) → Internet-facing
👉 HO-R1 = LAN ↔ WAN boundary
🔹 11.2 Branch Router — BR-R2
On BR-R2 → CLI:
show ip interface brief
Roles:
- Serial0/x/x → WAN (to HO-R1)
- GigabitEthernet0/1 → Branch LAN (to BR-SW4)
👉 BR-R2 = branch gateway
🔹 11.3 ISP Router — ISP-R0
On ISP-R0:
show ip interface brief
Role:
- Interfaces here represent public / ISP-side
- We won’t do much config on this device
👉 ISP-R0 = outside world
🔹 11.4 Distribution Switch — DIST-SW1
On DIST-SW1 → CLI:
show interfaces status
What to identify:
- Port to HO-R1 → uplink
- Port to BR-R2 → routed/uplink
- Ports to HQ-SW2 / HQ-SW3 → access-switch uplinks
👉 DIST-SW1 = traffic aggregator
🔹 11.5 Access Switches
HQ-SW2
- Ports → PCs (users)
HQ-SW3
- Ports → Server
- Ports → Wireless router
BR-SW4
- Ports → Branch PCs
- One uplink → BR-R2
👉 Access switches = end devices only
🧠 One-sentence summary (lock this in)
Routers connect networks; switches connect devices; serial = WAN; Ethernet = LAN.
🚫 Still NOT doing
❌ No IP addresses
❌ No VLANs
❌ No routing
❌ No DHCP
