Configure and Verify IPv4 and IPv6 Static Routing - CSU359 - Shoolini University

Configure and Verify IPv4 and IPv6 Static Routing

2024, September 9

0. Routing

Routing is the process of selecting a path for traffic in a network. In a computer network, routers perform routing by directing data packets between devices, ensuring they reach the correct destination. Routers use various algorithms and protocols to determine the best path for packet transmission. Routing can be categorized into different types based on how the routes are learned and maintained.

0.1 Routing Concepts

Routers maintain a routing table that contains information about how to reach different networks. When a data packet arrives, the router looks at the destination IP address, consults the routing table, and forwards the packet along the appropriate path.

Key Components of Routing:

0.2 Types of Routing

Routing can be broadly classified into three main categories: static routing, dynamic routing, and default routing. Each type has its own use cases and configuration methods.

0.2.1 Static Routing

Static routing is manually configured by network administrators. It involves defining explicit paths for network traffic and does not change unless manually updated. Static routing is useful for small, stable networks with predictable traffic flows.


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip}
0.2.2 Dynamic Routing

Dynamic routing is automatically managed by routing protocols, which allow routers to discover and maintain the best paths to network destinations. Routers share routing information with each other and adjust to changes in the network, such as link failures or topology changes.

0.3 Common Dynamic Routing Protocols

0.2.3 Default Routing

Default routing is a special type of static route used when no specific route is found for the destination in the routing table. The default route directs traffic to a default gateway, which is typically the router that connects the local network to the internet.


Router(config)# ip route 0.0.0.0 0.0.0.0 {next-hop-ip}

0.4 Interior vs. Exterior Routing Protocols

Routing protocols can also be classified into two categories based on where they operate: interior gateway protocols (IGPs) and exterior gateway protocols (EGPs).

0.4.1 Interior Gateway Protocols (IGPs)

Interior Gateway Protocols are used for routing within a single autonomous system (AS), which is typically an organization’s internal network. Common IGPs include RIP, OSPF, and EIGRP.

0.4.2 Exterior Gateway Protocols (EGPs)

Exterior Gateway Protocols are used for routing between different autonomous systems, usually on the internet. The most common EGP is BGP (Border Gateway Protocol), which manages routing between internet service providers (ISPs) and large enterprise networks.

0.5 Administrative Distance (AD)

Routers can learn about routes from different sources (e.g., static, RIP, OSPF, EIGRP). When multiple routes to the same destination are learned, the router uses the administrative distance (AD) to select the most trustworthy route. Lower AD values are preferred.

0.6 Metric

The metric is a value used to determine the best route when multiple routes exist to the same destination. Different routing protocols use different metrics:

0.7 Route Summarization

Route summarization is the process of combining multiple network routes into a single, summarized route. This reduces the size of the routing table and improves routing efficiency, especially in large networks.

0.8 Practical Considerations for Routing

1. Static Routing and Its Importance

Static routing refers to the manual configuration of routes by network administrators. In static routing, the routes are fixed, meaning they don't change unless manually updated. Unlike dynamic routing, static routing does not require routing protocols or automatic updates, making it simple and secure but less flexible for complex networks. Static routing is commonly used in smaller, stable networks where traffic patterns are predictable, or as a backup in larger, dynamic networks.

1.1 How Static Routing Works

In static routing, administrators manually define routes to specific networks by specifying the destination network, subnet mask, and next-hop IP address or exit interface. These routes are then stored in the router's routing table and used to forward packets to the specified destinations.

For example, to configure a static route to the network 192.168.10.0/24 through the next-hop IP address 192.168.1.1, the command would be:


Router(config)# ip route 192.168.10.0 255.255.255.0 192.168.1.1

This command instructs the router to forward all packets destined for 192.168.10.0/24 via the next-hop router at 192.168.1.1.

1.2 Key Components of Static Routing

1.3 Advantages of Static Routing

1.4 Disadvantages of Static Routing

1.5 Static Route Configuration Examples

1.5.1 IPv4 Static Route

To configure a static route for an IPv4 network, use the following command structure:


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip}

Example: Configuring a static route to 192.168.20.0/24:


Router(config)# ip route 192.168.20.0 255.255.255.0 192.168.1.1
1.5.2 IPv6 Static Route

To configure a static route for an IPv6 network, use the ipv6 route command:


Router(config)# ipv6 route {destination-network}/prefix {next-hop-ipv6}

Example: Configuring a static route to 2001:db8:1::/64:


Router(config)# ipv6 route 2001:db8:1::/64 2001:db8::1

1.6 Static Routing Use Cases

1.7 Administrative Distance in Static Routing

Static routes have an administrative distance (AD) of 1 by default, meaning they are highly trusted by the router. If you want a static route to serve as a backup for a dynamic route, you can increase its AD to make it less preferred.


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip} {administrative-distance}

Example: Configuring a floating static route with an AD of 200:


Router(config)# ip route 192.168.20.0 255.255.255.0 192.168.1.1 200

1.8 Verifying Static Routes

After configuring static routes, you can verify them using the following command:


Router# show ip route

This displays the routing table and shows all configured routes. Static routes will be indicated with the letter "S" in the output.

1.9 Importance of Static Routing

2. IPv4 and IPv6 Static Routing

Static routing for both IPv4 and IPv6 involves manually configuring specific routes on a router to direct network traffic to known destinations. These routes remain constant unless changed manually, making static routing suitable for simple, stable network environments or backup configurations in larger networks. The principles of static routing apply similarly to both IPv4 and IPv6, but the configuration commands and addressing schemes differ due to the nature of the protocols.

2.1 IPv4 Static Routing

IPv4 (Internet Protocol version 4) uses 32-bit addresses to identify network devices. Static routing in IPv4 involves specifying the destination network, the subnet mask, and the next-hop IP address or exit interface. IPv4 static routing is commonly used in small networks or where manual control over routing paths is required.

2.1.1 Configuring IPv4 Static Routes

The basic syntax for configuring an IPv4 static route is as follows:


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip/exit-interface}

For example, to configure a static route to the network 192.168.50.0/24 with the next-hop IP address 192.168.1.1, the command would be:


Router(config)# ip route 192.168.50.0 255.255.255.0 192.168.1.1
2.1.2 Verifying IPv4 Static Routes

After configuration, you can verify the static routes in the routing table using:


Router# show ip route

The static route will be listed with the prefix S in the output:


S    192.168.50.0/24 [1/0] via 192.168.1.1
2.1.3 Practical Considerations for IPv4 Static Routing

2.2 IPv6 Static Routing

IPv6 (Internet Protocol version 6) uses 128-bit addresses, allowing for a vastly larger address space than IPv4. Static routing in IPv6 is configured similarly to IPv4 but with some differences due to the structure of IPv6 addresses. IPv6 uses a prefix length rather than a subnet mask, and addresses are written in hexadecimal notation.

2.2.1 Configuring IPv6 Static Routes

The basic syntax for configuring an IPv6 static route is:


Router(config)# ipv6 route {destination-network}/{prefix-length} {next-hop-ipv6/exit-interface}

For example, to configure a static route to the network 2001:db8:1::/64 with the next-hop IP address 2001:db8::1, the command would be:


Router(config)# ipv6 route 2001:db8:1::/64 2001:db8::1
2.2.2 Verifying IPv6 Static Routes

To verify IPv6 static routes in the routing table, use the command:


Router# show ipv6 route

The static route will be displayed with the prefix S:


S    2001:db8:1::/64 [1/0] via 2001:db8::1
2.2.3 Practical Considerations for IPv6 Static Routing

2.3 Administrative Distance (AD) in Static Routing

Both IPv4 and IPv6 static routes have an administrative distance (AD) of 1 by default, making them highly trusted routes. You can adjust the AD to make static routes act as backup routes (floating static routes) by assigning a higher AD value:


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip} {administrative-distance}
Router(config)# ipv6 route {destination-network}/{prefix-length} {next-hop-ipv6} {administrative-distance}

2.4 Importance of Static Routing for IPv4 and IPv6

3. Default Route

In computer networks, static routing refers to manually configured routes in a router's routing table. A default route is a special type of static route that serves as a catch-all for packets addressed to networks that are not explicitly listed in the routing table. Configuring and verifying default routes is critical for ensuring that packets can reach destinations outside the local network when no specific route is known.

3.1 Default Route Overview

A default route is used when a router has no specific route for a destination network. The router forwards packets to the next-hop IP address defined by the default route.

Key Points:

3.2 Configuring IPv4 Static Default Route

To configure a static default route in IPv4, you use the command ip route followed by the default route and the next-hop address.


Router(config)# ip route 0.0.0.0 0.0.0.0 {next-hop-ip}

In this command:

3.3 Verifying IPv4 Static Default Route

After configuring the default route, you can verify it using the following command:


Router# show ip route

This command displays the routing table, and the default route should appear as:


S*    0.0.0.0/0 [1/0] via {next-hop-ip}

3.4 Configuring IPv6 Static Default Route

For IPv6, the default route is configured using the ipv6 route command:


Router(config)# ipv6 route ::/0 {next-hop-ipv6}

In this command:

3.5 Verifying IPv6 Static Default Route

Verification of the IPv6 default route is done using:


Router# show ipv6 route

You should see the default route listed as:


S*    ::/0 [1/0] via {next-hop-ipv6}

3.6 Practical Considerations

4. Network Route

A network route specifies a path that data packets must follow to reach a particular destination network. It is a foundational concept in routing, as routers use routes to determine how to forward packets to their destinations. The network route contains the network address and subnet mask, defining which network the route applies to, along with the next-hop address or exit interface.

4.1 Types of Network Routes

There are different types of network routes based on how they are defined and managed:

4.2 Static Network Route Configuration

A static network route is manually configured on the router, specifying a path to a specific destination network. This is often used for predictable, stable networks or in scenarios where dynamic routing is unnecessary.


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip}

For example, if a network administrator wants to configure a route to the network 192.168.10.0/24, the command would be:


Router(config)# ip route 192.168.10.0 255.255.255.0 192.168.1.1

4.3 Verifying Static Network Routes

To verify that a static route is correctly configured, the following command is used:


Router# show ip route

This displays the routing table, and the static route should appear as:


S    192.168.10.0/24 [1/0] via 192.168.1.1

4.4 Dynamic Network Routes

Dynamic routes are learned and managed by routing protocols such as OSPF, EIGRP, RIP, etc. The router automatically updates its routing table when the network topology changes, making dynamic routes suitable for larger, more complex networks.

To enable dynamic routing, configure the routing protocol. For example, to configure OSPF, use:


Router(config)# router ospf 1
Router(config-router)# network {network} {wildcard-mask} area {area-id}

This enables OSPF for the specified network and area.

4.5 Verifying Dynamic Network Routes

Dynamic routes can also be verified using the show ip route command. For OSPF, dynamic routes will appear with the identifier O, for EIGRP it will appear as D, and so on.


O    10.1.1.0/24 [110/2] via 10.1.1.2, 00:00:03, FastEthernet0/0

4.6 Route Administrative Distance and Metrics

When multiple routes to the same destination exist, routers use the administrative distance and metrics to select the best path.

4.7 Practical Considerations

5. Host Route

A host route is a route that directs traffic to a specific, single host. Unlike network routes, which target entire networks, a host route applies to only one device or IP address. This type of route is useful in situations where traffic needs to be routed to a particular host in a specific way, without affecting other devices on the network.

5.1 Host Route Characteristics

5.2 Configuring an IPv4 Host Route

A static host route is configured by specifying the destination IP address, a subnet mask of 255.255.255.255, and the next-hop address. Here is an example command:


Router(config)# ip route 192.168.1.10 255.255.255.255 {next-hop-ip}

In this example:

5.3 Configuring an IPv6 Host Route

In IPv6, a host route is configured similarly, using the /128 prefix length to represent a single host:


Router(config)# ipv6 route 2001:db8::1/128 {next-hop-ipv6}

In this command:

5.4 Verifying Host Routes

After configuring a host route, you can verify its presence in the routing table using the following command:


Router# show ip route

For IPv4, the host route should appear as:


S    192.168.1.10/32 [1/0] via {next-hop-ip}

For IPv6, use the following command:


Router# show ipv6 route

The host route will appear as:


S    2001:db8::1/128 [1/0] via {next-hop-ipv6}

5.5 Practical Applications of Host Routes

5.6 Limitations of Host Routes

6. Floating Static Route

A floating static route is a static route configured with a higher administrative distance than the primary route to a destination. It is used as a backup route, becoming active only when the primary route (usually a dynamically learned route) fails. Floating static routes provide redundancy in network routing without constantly influencing the primary routing decisions.

6.1 Understanding Floating Static Routes

In routing, the administrative distance (AD) is a value used by routers to select the best route when there are multiple routes to the same destination. Routes with a lower AD are preferred. A floating static route is configured with a higher AD than the primary route, allowing it to serve as a backup route.

6.2 Configuring a Floating Static Route

The configuration of a floating static route is similar to a standard static route, but with an additional parameter to set the administrative distance. The AD is added after the next-hop IP address in the command:


Router(config)# ip route {destination-network} {subnet-mask} {next-hop-ip} {administrative-distance}

For example, to configure a floating static route to the network 192.168.20.0/24 with an administrative distance of 200, you would use the following command:


Router(config)# ip route 192.168.20.0 255.255.255.0 192.168.1.1 200

In this command:

6.3 Verifying Floating Static Routes

To verify a floating static route, use the following command to check the routing table:


Router# show ip route

Initially, the floating static route will not appear in the routing table as long as the primary route is active. When the primary route fails, the floating static route will become visible and active.

6.4 Configuring a Floating Static Route for IPv6

To configure a floating static route for IPv6, the process is similar, but you use the ipv6 route command:


Router(config)# ipv6 route {destination-network}/prefix {next-hop-ipv6} {administrative-distance}

For example, to configure a floating static route for the network 2001:db8:1::/64 with an AD of 150:


Router(config)# ipv6 route 2001:db8:1::/64 2001:db8:0:1::1 150

6.5 Practical Applications of Floating Static Routes

6.6 Considerations for Floating Static Routes