Static Routing Advantages & Disadvantages, When we use Static Routes

Static Routing Advantages & Disadvantages, When we use Static Routes

This article is about the Static Routing Advantages & Disadvantages and When we use Static Routes. Static routes are the most simple way to configure the routing with any routing protocol.
A router can discover remote networks in two ways:

• Manually : remote networks are entered manually in the route table by means of static routes.
• Dynamically : remote routes are discovered automatically using a dynamic routing protocol.

Static routing provides both advantages and disadvantages compared to dynamic routing, for example:

Advantages of using static routing:

• Static routes are not advertised through the network, which increases security.
• Static routes consume less bandwidth than dynamic routing protocols. No CPU cycle is used to calculate and communicate routes.
• The route that uses a static route to send data is known.

Disadvantages of using static routing:

• Initial setup and maintenance are prolonged.
• The configuration is prone to errors, especially in large networks.
• Administrator intervention is required to maintain changing route information.
• It does not adapt well to growing networks; Maintenance becomes increasingly complicated.
• It requires a complete knowledge of the entire network for proper implementation.

Dynamic And Static Routing:

The following table compares the characteristics of dynamic routing and static routing. Note that the advantages of one method are the disadvantages of the other.

Comparison table between dynamic and static routing.

Dynamic routing	Static routing
Network size independent configuration	Configuration becomes more complex as network size increases
Automatically adapts to topology changes	Administrator intervention is required if the topology changes
Suitable for simple and complex topologies	Suitable for simple topologies
Less Safe	Safer
Uses CPU, Memory and range bandwidth	No need for additional resources
The route depends on the current topology	The route to destination is always the same

In summary, static routes are useful for smaller networks with only one route to an external network. They also provide security on a larger network for certain types of traffic or links to other networks that need more control. It is important to understand that static routing and dynamic routing are not mutually exclusive.
Remember that the administrative distance (AD) value is a measure of the preference of route sources. Route origins with low AD values ​​are preferred over route origins with high AD values. The value of AD for a static route is 1. Therefore, a static route will have priority over all dynamically learned routes, which will have values ​​greater than AD.

When we use Static Routes

Static routing has three main uses:

1. It facilitates the maintenance of the routing table in smaller networks in which they are not expected to grow significantly.
2. It provides routing to and from internal route networks . An internal route network is one that is accessed through a single route and whose router has only one neighbor.
3. Use a single default route to represent a route to any network that does not have a more specific match with another route in the routing table.

The following image shows an example of the connection of an internal route network and the connection of a predetermined route. Note that any network connected to R1 has only one way to reach other destinations (R2 for example). Therefore, the 172.16.3.0 network is an internal route network and the R1 is an internal route router.

In this example, you can configure a static route on R2 to reach the R1 LAN. Also, since R1 has only one way to send non-local traffic, a default static route can be configured on R1 to point to R2 as the next hop for all other networks.

Types of Static Routes

Static routes are often used more frequently to connect to a specific network or to provide a gateway of last resort for an internal route network. They can also be used for the following:

• To reduce the number of routes announced by summarizing several contiguous networks as a single static route
• To create a backup route in case a link in the main route fails

Well, we will see the following types of static routes IPv4 and IPv6:

• Standard static route
• Default static route
• Summary Static Route
• Floating static route

 STANDARD STATIC ROUTE

IPv4 and IPv6 support the configuration of static routes. Static routes are useful for connecting to a specific remote network.

DEFAULT STATIC ROUTE

A default or default route is a route that matches all packets and is used by the router if a packet does not match any other more specific route in the routing table. In addition, it  can be learned dynamically or statically configured . A default static route is simply a static route with 0.0.0.0/0 as the destination IPv4 address. When configuring a default static route, a gateway of last resort is created.
Default static routes are used in the following cases:

• When no other route in the routing table matches the destination IP address of the packet. In other words, when there is no more specific match. They are commonly used when connecting a company's peripheral router to the ISP network.
• When a router has another unique router to which it is connected. In this situation, the router is known as an internal route router.

SUMMARY STATIC ROUTE

To reduce the number of entries in the routing table, several static routes can be summarized in a single static route if the following conditions are met:

• The destination networks are contiguous and can be summarized in a single network address.
• All static routes use the same exit interface or IP address of the next hop.

FLOATING STATIC ROUTE

Floating static routes are static routes that are used to provide a backup route to a main static or dynamic route , in the event of a link failure. The floating static route is used only when the main route is not available.
To achieve this, the floating static route is configured with an administrative distance greater than the main route. Administrative distance represents the reliability of a route. If there are several routes to the destination, the router will choose the one with the least administrative distance.
For example, suppose an administrator wants to create a floating static route as a backup for a route discovered by EIGRP. The floating static route must be configured with an administrative distance greater than the EIGRP. The EIGRP has an administrative distance of 90. If the floating static route is configured with an administrative distance of 95, the dynamic route discovered by the EIGRP is preferred to the floating static route. If the route discovered by the EIGRP is lost, the floating static route is used instead.