Static Routing

Static routing is a method of manually configuring routes in a router’s routing table. In this approach:

• The network administrator defines the path for data packets manually.

• Unlike dynamic routing, routers do not automatically learn routes.

• Dynamic routing uses protocols like RIP and OSPF to discover routes automatically.

Introduction to Router

A router is a networking device that connects multiple computer networks and directs data packets between them.

Key Functions:

• Operates at Layer 3 (Network Layer) of the OSI model, Analyzes incoming data packets to determine destination address.

• Determines the best path to forward incoming packets.

• Facilitates communication between different IP networks.

• Manages traffic between different IP networks like LANs (Local Area Networks) and the WAN (Wide Area Network).

Cisco Router Configuration Modes:

Mode	Prompt	Description
User EXEC Mode	Router>	Basic monitoring commands
Privileged EXEC Mode	Router#	Full access to show and debug commands
Global Config Mode	Router(config)#	Configure global router settings
Interface Config Mode	Router(config-if)#	Configure individual interfaces

For Modes of Cisco Router Configuration

Cisco routers operate through a hierarchical command-line interface with different modes, each serving specific purposes in configuration and monitoring. The four primary configuration modes are:

1. User EXEC Mode

• Prompt: Router>

• Access Level: Basic user access; read-only.

• Entered by: Logging into the router.

• Purpose: Basic monitoring and diagnostics. No configuration allowed.

• Exit: Type logout or exit.

Common Commands:

• ping 8.8.8.8 – Test connectivity to a remote host.

• traceroute 8.8.8.8 – Show the path packets take to Google DNS.

• show version – Display IOS version and system information.

• show ip interface brief – Summarize interfaces and statuses.

• ? – View available commands.

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2. Privileged EXEC Mode

• Prompt: Router#

• Access Level: Full read access and limited write access.

• Entered by: Typing enable from User EXEC Mode.

• Purpose: View detailed configuration, debug, and access all operational commands.

• Exit: Use disable to return to User EXEC Mode.

Common Commands:

• show running-config – Display current configuration.

• show startup-config – View saved configuration in NVRAM.

• copy running-config startup-config – Save current configuration.

• reload – Reboot the router.

• debug [option] – Enable troubleshooting/debugging.

• configure terminal – Enter Global Configuration Mode.

• Ctrl + Z – Return to Privileged EXEC Mode from any configuration mode.

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3. Global Configuration Mode

• Prompt: Router(config)#

• Access Level: Full write access to system-wide settings.

• Entered by: Typing configure terminal from Privileged EXEC Mode.

• Purpose: Modify global device configurations.

• Exit: Use exit to return to Privileged EXEC Mode or Ctrl + Z.

Common Commands:

• hostname CoreRouter – Change the device name.

• enable secret [password] – Set encrypted Privileged EXEC password.

• line console 0 / line vty 0 4 – Configure console/remote access.

• interface FastEthernet0/0 – Enter Interface Configuration Mode.

• ip route [dest] [mask] [next-hop] – Add static routes.

• ip route 10.0.0.0 255.0.0.0 192.168.1.2 — Add static route to 10.0.0.0 via 192.168.1.2

• banner motd #Message# – Set login banner message.

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4. Interface Configuration Mode

• Prompt: Router(config-if)#

• Access Level: Modify settings specific to an interface.

• Entered by: From Global Config Mode: interface [type] [number]
  (e.g., interface FastEthernet0/0)

• Purpose: Configure individual router interfaces (IP, speed, duplex).

• Exit: Use exit to return to Global Configuration Mode.

Common Commands:

• ip address 192.168.1.1 255.255.255.0 – Assign IP address.

• no shutdown – Enable the interface (bring it up).

• shutdown – Disable the interface.

• description Link-to-Switch1 – Label interface.

• duplex full – Set full-duplex communication.

• speed 100 – Set speed to 100 Mbps.

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Useful Keyboard Shortcuts and CLI Tips

Shortcut	Function
TAB	Auto-complete the current command.
?	Display available commands or options.
Ctrl + C	Cancel current command or operation.
Ctrl + Z	Exit to Privileged EXEC Mode.
UP/DOWN arrows	Scroll through command history.
SHOW ?	List all "show" command options.

Static Routing Configuration Example

Configure static routing between R1 and R2 using FastEthernet interfaces.

Network Details

Router	Interface	IP Address	Network
R1	FastEthernet0/0	10.0.0.1	10.0.0.0/8
R1	FastEthernet0/1	20.0.0.1	20.0.0.0/8
R2	FastEthernet0/0	20.0.0.2	20.0.0.0/8
R2	FastEthernet0/1	30.0.0.1	30.0.0.0/8

Interconnecting Network (between R1 and R2): 20.0.0.0/8

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Configuration Steps

Static Route Syntax

ip route <destination-network> <subnet-mask> <next-hop-IP>

R1 Configuration

R1# configure terminal
R1(config)# interface fastethernet0/0
R1(config-if)# ip address 10.0.0.1 255.0.0.0
R1(config-if)# no shutdown
R1(config-if)# exit

R1(config)# interface fastethernet0/1
R1(config-if)# ip address 20.0.0.1 255.0.0.0
R1(config-if)# no shutdown
R1(config-if)# exit

Telling R1: "To reach the 30.0.0.0 network, send traffic to 20.0.0.2 (R2)."

R1(config)# ip route 30.0.0.0 255.0.0.0 20.0.0.2

Checking Configuration

R1# show ip route
R1# show ip interface brief

R2 Configuration

R2# configure terminal
R2(config)# interface fastethernet0/0
R2(config-if)# ip address 20.0.0.2 255.0.0.0
R2(config-if)# no shutdown
R2(config-if)# exit

R2(config)# interface fastethernet0/1
R2(config-if)# ip address 30.0.0.1 255.0.0.0
R2(config-if)# no shutdown
R2(config-if)# exit

Tells R2: "To reach the 10.0.0.0 network, send traffic to 20.0.0.1 (R1)."

R2(config)# ip route 10.0.0.0 255.0.0.0 20.0.0.1

R2# show ip route
R2# show ip interface brief

Expected Outcome

• All interfaces should be in up/up state after using no shutdown.

• R1 and R2 should successfully ping each other's LAN IPs:

  • From R1: ping 30.0.0.1

  • From R2: ping 10.0.0.1

• show ip route should display manually configured static routes.

• show ip interface brief should confirm correct IP assignments and interface status.