Introduction to Static Routing

Static routing provides a simple, efficient, and reliable solution for routing traffic in a network, particularly in smaller networks, or where network resources are limited. Usually, such networks are very small companies, branch offices, or even home networks, also known as Small Office/Home Office (SOHO), that have become a very popular working environment in the last several years.

While dynamic routing protocols are more common in large enterprise networks, where they easily adapt to topology changes, static routing, as the name suggests, is more static and heavily depends on network administrators to configure it manually. 

Although it can become difficult to manage static routing as the network grows in size or complexity, at the same time, it provides several benefits such as reliability, path control, efficiency, improved security, and cost-effectiveness.

Static Routing: An In-depth Overview

Static routing is a type of routing where network administrators manually configure the routes packets take to reach their ultimate destination. Unlike dynamic routing protocols, which automatically update the routing tables based on changes in the network topology, static routing does not involve exchanging routing information between routers or other routing-capable devices.

Instead, routes remain fixed until they are modified or removed from the device configuration. As a result, routes are not automatically adjusted in response to changes in a network topology. 

When to Use Static Routing

Static routing is generally considered less efficient and more error-prone than dynamic routing protocols. However, static routing can be useful when there is a need for tight control over network traffic or where the network is simple enough.

Therefore, static routing is unsuitable for large, complex, or dynamic networks as it requires a lot of manual configuration and management.

Static routing is typically used in small networks or situations where the infrastructure is relatively stable and does not change frequently. One of the most common use cases for static routing is point-to-point links and situations when no additional paths exist between the connected locations.

In static routing, the administrator configures routes manually to each network that the router should know about to be able to send packets there. A static route contains a destination network and its corresponding next-hop address (neighboring router). Once configured, the static route becomes available in the routing table.

When a packet arrives at a router, the router checks its routing table to determine the next-hop address for the packet. The router then forwards the packet to this address, which could be a directly connected network or another router on the path to the destination.

The administrative distance (AD) of a static route is 1 by default. This makes it a worse option than directly connected networks, but always a better routing source than any of the routing protocols. The AD can also be manually changed to a different value, which is usually used when configuring backup routes to the same network.

The Importance of a Default Route

As simple as static routing is, configuring static routes to many networks can be cumbersome. Using static routes to networks spread out in a topology that shares the same exit point (next-hop address) complicates the overall configuration and makes the routing tables bigger. 

However, the key point of static routing is that it requires the router to contain a route to every possible network, which in some cases can be very difficult or even impossible, such as for internet traffic. 

The solution comes in the form of a default route which is also a static route, but instead of pointing to a specific network, it points to any location. It is also known as the gateway of last resort or simply a default gateway. 

A default route is used to route packets for which no specific matching route is found in the routing table. Instead of dropping these packets, the default route allows the router to forward them to a pre-defined gateway or next-hop address.

In addition to improving static routing by providing a fallback option in case of unknown destinations, it also allows for more efficient traffic routing, reducing the need for manual configuration of specific routes for every destination. Using a default route allows the router to communicate to any network available on the internet.