Pros and Cons of Static Routing - dummies

By Edward Tetz

Routing protocols interfaces can be dynamically or statically assigned. Static network routing has benefits and drawbacks as compared to implementing dynamic routing protocols. On the benefit side, you have the following:

  • Predictability: If you change your network design and layout and suffer from a device failure, static routes do not change. You always know the path your data will take.

  • Network bandwidth overhead: Static routing has zero overhead, whereas all dynamic routing protocols have some degree of overhead. For example, on a network with 200 segments, the router will send updates from each interface every 30 seconds, and those updates are about 3KB of data. Over the course of a day, this traffic adds up.

  • Easy to configure: This issue is relative, depending on the size of your network. Although small networks are easy to configure, as a network grows, applying changes to all the routers can become a big task.

The few drawbacks to static routing include the following:

  • Lack of scalability: For the 200 segment network mentioned previously, which possibly contains 200 routers, you could be dealing with thousands of routing table entries. Manually calculating all those routes and keeping them up-to-date would be a Herculean task and very prone to error. Even if you implement a good network-addressing design that allows for route summarization, you are still left with an overwhelming number of routes to manage.

  • Large network implementation: When working with a network of 200 routers, the task of updating one route can become a complex task, especially if you update the routes in the wrong order. In that case, you could lose access to a large section of the network until someone visits that router with a rollover cable or connects from another area of the network.

  • No redundancy: Dynamic routing protocols can update routing tables in the event of device or interface failure, so if there are multiple possible paths, these protocols will continue to allow data flow. Static routes do not allow for this automatic failover or redundant paths, so if you have a failure, you must manually adjust routes to move data through an alternative path.