This section of the CCNA exam covers the static routes, for both IPv4 and IPv6.

There are three types of routes that you will find in the routing table;

  • the static routes,
  • connected and
  • routing protocol routes.

The static routes are added to the routing table through manual configuration by an administrator; this has its advantages and disadvantages. Each static route is configured using “ip route” or “ipv6 route”. It is important to understand the different types of static routes.

As an Administrator,  when you configure an IP address to a routers interface, it automatically adds a connected and local route to its routing table and its able to route traffic between it’s different connected interfaces. But if a router want to send traffic to a subnet that it is NOT directly connected to, then it’s going to need some way to know how to get there. You can either do it as an administrator by adding a static route on the router as we will be doing shortly or the router can learn those routes dynamically through a routing protocol.

 

In this example, Router-1 is only directly connected to 10.1.0.0 /24 and 10.0.0.0/24 networks, so, it can route traffic to both networks but will not be able to router traffic to 10.0.1.0/24 and 10.0.2.0/24 networks behind Router-2. So, we must tell it how to get there;

 

 

  • Rt1(config)#ip route 10.0.1.0 255.255.255.0 10.0.0.2
  • Rt1(config)#ip route 10.0.2.0 255.255.255.0 10.0.0.2
  • Rt1(config)#exit

Similarly, Router-2 is only directly connected to 10.0.0.0/24, 10.0.1.0/24 and 10.0.2.0/24 networks, so, it can route traffic between the three networks but will NOT be able to router traffic to 10.1.0.0 /24 network behind Router-1. So, we must tell it how to get there;

  • Rt2(config)#ip route 10.1.0.0 255.255.255.0 10.0.0.1
  • Rt2(config)#exit

Let’s add another router to the existing two routers called router 3

Router 3 (connected to 10.1.1.0 and 10.1.0.0 networks but has three networks that it cannot reach)

  • Rt3(config)#ip route 10.0.0.0 255.255.255.0 10.1.0.2
  • Rt3(config)#ip route 10.0.1.0 255.255.255.0 10.1.0.2
  • Rt3(config)#ip route 10.0.2.0 255.255.255.0 10.1.0.2
  • Rt3(config)#exit

Router 1 (connected to 10.1.0.0 and 10.0.0.0 networks but has three networks that it cannot reach)

  • Rt1(config)#ip route 10.1.1.0 255.255.255.0 10.1.0.1
  • Rt1(config)#ip route 10.0.1.0 255.255.255.0 10.0.0.2
  • Rt1(config)#ip route 10.0.2.0 255.255.255.0 10.0.0.2
  • Rt1(config)#exit

Router 2 (connected to 10.0.0.0, 10.0.1.0 and 10.0.2.0 networks but has two networks that it cannot reach)

  • Rt2(config)#ip route 10.1.0.0 255.255.255.0 10.0.0.1
  • Rt2(config)#ip route 10.1.1.0 255.255.255.0 10.0.0.1
  • Rt2(config)#exit

Once we have configured all the these routes, we are going to have reachability between all the different subnets on our network.

IPV6 Configuration

The configuration is the same for IPV6 as shown, **<<More details about IPV6>>.**

Example: Configure a static route to 2001:aaa::/64 using serial 0/0 interface

3.3.a Default route

Simply put, a default route is used to route traffic to any network that is not in your routing table. Any traffic destined to a network that is not in the routing table will be dropped by the router without a default route defined.

  • It’s a router saying I don’t know how to get to that destination, so I will send it to my default route which sends it to the next hop and I am sure the next hop router will take care of it.
  • A default static route is a destination IP address 0.0.0.0/0.

Configuration 1

Ipv4 Config -( ip route 0.0.0.0 0.0.0.0 <ip for next-hop OR exit interface on the router>)

Ipv6 Config  -( ip route ::/0 <ip for next-hop OR exit interface on the router>)

  • Rt3(config)#ip route 0.0.0.0 0.0.0.0 10.1.0.2
  • Rt3(config)#end

Verify

 

 

 

 

 

 

Our static default route appears in the table;

  • Static default route as(S*),
  • 0.0.0/0 as the destination ip address,
  • Connected route as 1 in [1/0], 0 as the metric
  • via =next hop,
  • 10.1.0.2 =next hop ipv4 address

(Any destination you don’t know, pass it over to 10.1.0.2 next hop, which is also the gateway of last resort, especially when dealing with a network with a single exit point.)

Configuration 2

  • Rt3(config)#ip route 0.0.0.0 0.0.0.0 10.1.0.1
  • Rt3(config)#ip route 0.0.0.0 0.0.0.0 10.0.0.2
  • Rt3(config)#end

(Any destination you don’t know, pass it over to 10.1.0.1 next hop on the networks to the left, 10.0.0.2 represents for the networks on the right)

Verify

3.3.b Network route

A static route that comprise a subnet. A network route configured to route traffic to a specific network. Without a network route, packets will get routed via the default route if one exists

A network route identifies the network, network mask and next hop IP address to send packets to. The network mask in a network route can be /1 through /31

Note:

The network mask in a network route cannot be /0, that will make it a (default route), It cannot also be /32 which will make it a (host route). From the rule of specificity, a More specific network route takes precedence over less specific network routes (based on the network mask)

Configure an IPv4 network route by typing:

Ipv4 Config Configuration

  • – (ip route < network-to-route-to > <subnet-mask> <exit interface on the router OR next-hop ip address>)

Ipv6 Config Configuration

  • – (ipv6 route <network-to-route-to>/ <subnet-mask> <exit interface on the router OR next-hop ip address>)

Example of Network route

  • Rt3(config)#ip route 192.168.1.0 255.255.255.0 10.10.10.2
  • Rt3(config)#end

3.3.c Host route

A host route is used to route traffic to a specific host NOT Network.  The subnet mask in the route will always be all 1’s which means non CIDR is 255.25.255.255 that is /32 for IPv4 and /128 for IPv6.

  • Host routes are automatically added to the routing table for all IPv4 and IPv6 addresses that are configured on the router interfaces
  • The Host routes are the most specific route possible and therefore take precedence over all other routes (based on the network mask)

Configuration

Ipv4 Config

  • – (ip route < host-to-route-to > <subnet-mask> <exit interface on the router OR next-hop ip address>)

Ipv6 Config

  • – (ipv6 route < host-to-route-to >/ <subnet-mask> <exit interface on the router OR next-hop ip address>)

Example        

  • Rt3(config)#ip route 172.16.1.3 255.255.255.255 10.10.10.2
  • Rt3(config)#end

3.3.d Floating static

A floating static route is a static route with an administrative distance higher than that of the static or dynamic routing protocol in use. They are very useful in providing a backup to a primary link. 

Floating static routes act as a backup route should the preferred dynamic routing protocol lose its neighbor relationships and thereby having its routes removed from the routing table. When the dynamic routes are removed from the routing table, the floating static route is inserted into the routing table since it has the next best administrative distance

Example

            So, if OSPF is the preferred routing protocol to use, its AD 110.

You will then set your floating static to be 111 or greater

Ipv4 Config Configuration format

– (ip route < Network-to-route-to> <subnet-mask> <exit interface on the router OR next-hop ip address> 111)

Ipv6 Config Configuration format

– (ipv6 route < Network-to-route-to >/ <subnet-mask> <exit interface on the router OR next-hop ip address> 111)

Example        

  • Rt3(config)#ip route 192.168.1.0 255.255.255.0 10.10.10.2 111
  • Rt3(config)#end