Different types of routes

In INTT, there are 5 types of routes
1) Connected routes
2) Static routes
3) Dynamic routes
4) Summary routes
5) Default routes

1) Connected routes are routes which are automatically created in the routing table upon entering the following commands to configure the interfaces

conf t
int fax/x or sx/x/x
ip address <host address> <subnet mask>
no shut

As long as the interfaces are configured in the router and are shown to be up and running, the router will assume that the interfaces belong to active subnets which are directly connected and thus, they create connected routes to them. Connected routes have a AD of 0 which is the highest in terms of trustworthiness in Cisco routers.

2) Static routes are routes which are created manually by operators. It is often denoted in the format as shown

ip route <destination network address> <subnet mask> <exit interface/next hop address>

In Newton's third law of motion where action and reaction are equal and opposite, we can infer that for every static path we create, there should be a reverse path. It is because most devices exchange requests and responses and there is a need for bi-directional paths. In choosing whether to use exit interfaces or next hop addresses, there are a few points to note. Firstly, static routes based on exit interfaces have faster lookup than next hop addresses. However, exit interfaces are more useful for serial point to point connections where there is only one device at each end. For ethernet networks, it is better to use next hop addresses to prevent flooding. Static routes AD is 1, which is less trustworthy than connected routes

3) Dynamic routes are routes created by the routers automatically. They do it by activating dynamic routing protocols. These protocols help the routers to advertise their directly connected networks to other routers using routing updates. They also calculate the best paths from these routing updates and place them inside the routing table. For RIP, the commands are as follows

router rip
network <directly connected network #1>
network <directly connected network #2>

For INTT, we learning about RIPv1 which is classful routing protocols and RIPv2, OSPF, EIGRP which are classless routing protocols. Classful routing protocols advertise their network addresses only while classless routing protocols advertise their network addresses and subnet masks. More details will be covered in my classes later on.

3) Summary routes are routes which combine various routes into a single route. This reduces the size of the routing table and makes routing faster. The tradeoff is that accurarcy of routing will be compromised as unwanted ip addresses get forwarded instead of dropped while using summarization.

4) Default routes are routes of the last resort. When the packets have no matching routing entries, the default route is used to forward the packets. Once a default route is created, no packets will be dropped by the router. All packets with unknown destinations will be forward through s0/0/0, in the case below.

ip route 0.0.0.0 0.0.0.0 s0/0/0

In case of a stub router, default routes can be used to summarized all the routes into one route.