Router-in-the-middle FTP/HTTP lab (Packet Tracer)¶

Theory prerequisites

Read Packets & IP Addressing, Switches vs Routers, and Subnetting & DHCP. Return to the Lab-Aligned Learning Path after verification.

This lab builds directly on the router-in-the-middle architecture by implementing VLSM / Subnetting (/26 with mask 255.255.255.192) across two separate broadcast domains.

The server now lives on a different subnet, reached through a router. This is the smallest possible step up that actually requires routing (no NAT yet — that's a separate concept).

All IP addresses are statically assigned without DHCP or external internet connectivity.

Topology¶

Addressing Plan¶

Subnet 1 Network: 192.168.1.0/26 (Usable: 192.168.1.1 – 192.168.1.62, Mask: 255.255.255.192, Broadcast: 192.168.1.63)
Subnet 2 Network: 192.168.1.64/26 (Usable: 192.168.1.65 – 192.168.1.126, Mask: 255.255.255.192, Broadcast: 192.168.1.127)

Device	Interface	IP Address	Subnet Mask	Default Gateway	Role / Notes
Router0	`Gig0/0`	`192.168.1.1`	`255.255.255.192`	—	Subnet 1 Default Gateway
Router0	`Gig0/1`	`192.168.1.65`	`255.255.255.192`	—	Subnet 2 Default Gateway
PC1	`Fa0`	`192.168.1.11`	`255.255.255.192`	`192.168.1.1`	Subnet 1 Client (MAC: `0001.1111.1111`)
PC2	`Fa0`	`192.168.1.22`	`255.255.255.192`	`192.168.1.1`	Subnet 1 Client (MAC: `0002.2222.2222`)
Server0	`Fa0`	`192.168.1.100`	`255.255.255.192`	`192.168.1.65`	Subnet 2 HTTP / FTP Server
Laptop0	`Fa0`	`192.168.1.70`	`255.255.255.192`	`192.168.1.65`	Subnet 2 Client

1. Place Devices¶

2x Generic PC (PC1, PC2)
1x Laptop (Laptop0)
2x Switch (2960-24TT: Switch0, Switch1)
1x Router (1941: Router0)
1x Server (Server0)

2. Cable Devices (Copper Straight-Through)¶

Subnet 1 Connections¶

PC1 (FastEthernet0) <—> Switch0 (FastEthernet0/2)
PC2 (FastEthernet0) <—> Switch0 (FastEthernet0/1)
Switch0 (FastEthernet0/3) <—> Router0 (GigabitEthernet0/0)

Subnet 2 Connections¶

Router0 (GigabitEthernet0/1) <—> Switch1 (FastEthernet0/1)
Switch1 (FastEthernet0/2) <—> Server0 (FastEthernet0)
Switch1 (FastEthernet0/3) <—> Laptop0 (FastEthernet0)

3. Router0 Configuration¶

Open the CLI on Router0 and execute the following configuration:

enable
configure terminal
hostname Router0

! Subnet 1 Gateway Configuration
interface GigabitEthernet0/0
 ip address 192.168.1.1 255.255.255.192
 no shutdown
exit

! Subnet 2 Gateway Configuration
interface GigabitEthernet0/1
 ip address 192.168.1.65 255.255.255.192
 no shutdown
exit

end
write memory

Note: No dynamic routing protocol or static routes are needed because Router0 has directly connected interfaces in both Subnet 1 and Subnet 2.

4. Host Configuration (Static IP Setup)¶

Open each end device and configure static IP settings under Desktop > IP Configuration:

Subnet 1 Hosts¶

PC1:
IP Address: 192.168.1.11
Subnet Mask: 255.255.255.192
Default Gateway: 192.168.1.1
PC2:
IP Address: 192.168.1.22
Subnet Mask: 255.255.255.192
Default Gateway: 192.168.1.1

Subnet 2 Hosts¶

Server0:
IP Address: 192.168.1.100
Subnet Mask: 255.255.255.192
Default Gateway: 192.168.1.65
Laptop0:
IP Address: 192.168.1.70
Subnet Mask: 255.255.255.192
Default Gateway: 192.168.1.65

5. Enable HTTP & FTP Services on Server0¶

Navigate to Server0 > Config tab > Services: * HTTP: Ensure HTTP and HTTPS services are toggled On. * FTP: Ensure FTP service is toggled On. Under user accounts, add username cisco / password cisco with all permissions (Read, Write, Delete, Rename, List) checked.

6. Verification and Testing¶

From PC1 or PC2 in Subnet 1:

A. ICMP Ping Test¶

Open Desktop > Command Prompt and test connectivity across subnets:

ping 192.168.1.100

(The first ping packet may time out while ARP resolves across hops; subsequent pings will succeed with TTL decremented to 127/254).

B. HTTP Web Browser Test¶

Open Desktop > Web Browser and navigate to:

http://192.168.1.100

You should see the default Cisco Packet Tracer web page.

C. FTP Client Test¶

Open Desktop > Command Prompt and run:

ftp 192.168.1.100

Enter username cisco and password cisco. Once authenticated, verify file access:

dir
get index.html
quit

7. Key Observations & Troubleshooting¶

Action / Verification	Concept Demonstrated
`show ip route` on Router0	Displays two directly connected routes (`192.168.1.0/26` on `Gig0/0` and `192.168.1.64/26` on `Gig0/1`).
Why `255.255.255.192` is required	Prevents subnet overlap errors on Router0 and defines two distinct broadcast domains of 62 usable IPs each.
Removing Default Gateway on PC1	Cross-subnet ping fails because PC1 cannot determine where to forward non-local traffic without a gateway.
Packet Tracer Simulation Mode	Inspect how Ethernet frame MAC addresses change at each L2 hop while source and destination IP addresses remain constant end-to-end.

Observe ARP in 1-Router Lab¶

Take 5 minutes to observe ARP in Packet Tracer using Simulation Mode:

In your current lab, switch from Realtime to Simulation mode (bottom right icon).
Ping from PC1 (192.168.1.11) to Server0 (192.168.1.100).
Click the Play / Forward button step-by-step:
Notice that PC1 creates an ICMP packet, but it cannot send it yet because it doesn't know the MAC address of its Gateway (192.168.1.1).
PC1 broadcasts an ARP request (Who has 192.168.1.1?).
Once Router0 replies with its MAC address, PC1 sends the ICMP ping.
On PC1's command prompt, type:
```
arp -a
```
You will see the Gateway IP mapped to Router0’s physical MAC address.