Cisco Network Fundamentals // Static Routes

Welcome to the first of my Cisco Network Fundamentals series

I will be covering all sorts from the exam topics, including live simulation scenarios. Long reads have their place but I wanted these to be something you could quickly review on a coffee break. Also, even though the primary focus it exam prep, my hope is that they will be read by anyone looking for on point, quick review knowledge.

Lets get started..

In order for routers to forward packets to remote networks, they must know how to reach them. There are two options: static or dynamic routes.

Static routes are manually configured on each router. They are used for a couple of reasons:

• where there is only a single path to a network (a.k.a. stub network)

• when connecting to an ISP and configuring it as a default (static) route

There are a number of problems with implementing static routes network-wide. Some include:

• failure to scale well

• does not automatically react/recover to changes in the network

• tedious to configure for large networks (see point 1)

To configure a static route:

R1(conf)# ip route prefix mask address | interface [distance]

The prefix and mask is the destination network and subnet mask. You can use an address to define the IP address of the next hop towards the destination network or specify a local router interface that the router will use to send traffic out to the destination network. The optional distance keyword can be used to manually define the administrative distance for the route.

Static Default Routes

One of the most common uses of static routes is for creating a default route. There are often cases when you want to forward packets that are not defined in a specific route out an interface or towards another router. A common example is when connecting to an ISP. If traffic is destined for an address range not defined within your organization (i.e. your coworker’s Facebook updates), then it makes sense to configure a default route towards your ISP or other organization.

To configure a static default route:

R1(conf)# ip route 0.0.0.0 0.0.0.0 address | interface ]

Floating Static Routes

There are some circumstances when it makes sense to use a static route as a backup to a dynamic routing protocol. In order for this to work, however, the default administrative distance value on the static route must be raised so it will have a lower priority than the dynamic routing protocol.

If you would like help with the Cisco Route 300-101 prep or any other Cisco exam, I offer a mentor program. Feel free to get in touch to find out more.