Goal of this step
- Give IP addresses to the serial WAN link
- Bring the link UP
- NO routing yet
🔹 What we are configuring (very clear)
- Link: Serial between HO-R1 and BR-R2
- Network:
10.255.255.0 /30 - Only two usable IPs (perfect for WAN)
| Device | Interface | IP |
|---|---|---|
| HO-R1 | Serial | 10.255.255.1 /30 |
| BR-R2 | Serial | 10.255.255.2 /30 |
🔹 STEP 15.1 — Configure WAN on HO-R1
- Click HO-R1 → CLI
- Type exactly (adjust serial number if needed, e.g.
0/3/0):
enable
configure terminal
interface serial 0/3/0
ip address 10.255.255.1 255.255.255.252
no shutdown
⚠️ If HO-R1 is the DCE side, add:
clock rate 64000
Then:
end
write memory
🔹 STEP 15.2 — Configure WAN on BR-R2
- Click BR-R2 → CLI
- Type:
enable
configure terminal
interface serial 0/3/0
ip address 10.255.255.2 255.255.255.252
no shutdown
end
write memory
🔹 STEP 15.3 — Verify WAN link (LOOK only)
On either router:
show ip interface brief
You want to see:
- Serial interface → up / up
🔹 STEP 15.4 — Test WAN connectivity
From HO-R1:
ping 10.255.255.2
✅ You should get replies.
🧠 What you just learned
- WAN links use small subnets
- Serial links require no shutdown
- DCE side provides clocking
- Two routers can now talk directly
🚫 STOP HERE
❌ No routing
❌ No OSPF
❌ No static routes
❌ No ISP yet
