Traceroute

traceroute 1.1.1.1

Right now, the packet is going through R1→R2→R6 which is the best route with the longest prefix match.

We have now shut down R1’s f0/0 interface:

int f0/0
 shutdown

Now we traceroute:

Now the packet is following the path R1→R3→R6 because EIGRP has a lower AD value than OSPF and the EIGRP path through R1→R4→R6 has a higher metric value (increased it by lowering R4 f2/1 interface bandwidth).

We are currently shutting down R1’s f1/0 interface:

int f1/0
 shutdown

Now we traceroute again:

Now the packet is following the path R1→R4→R6 because EIGRP has a lower AD value than OSPF.

We have now shut down R1’s f2/0 interface:

int f2/0
 shutdown

Now we traceroute again:

Now R1→R5→R6 is the path left for R1 to reach R6’s loopback.

Pre-requisites: EIGRP, OSPF, Static Routing, AD value.

Static routing is a routing protocol that helps to keep your network organized and to optimize routing performance. It enables the router to assign a specific path to each network segment and to keep track of network changes. This helps to improve network stability and continuity. This adds security because a single administrator can only authorize routing to particular networks.

We are going to see how a router selects the best path for a packet, which is decided based on:

1. Longest Prefix
2. Lowest AD value
3. Lowest Metric value