Both R1 and R3 advertise 13.13.13.13/32 network into RIP domain
R3 is configured to offset all network updates via interface fa1/0 by 10
R2 receives R3 route with a metric of 11 hops
A debug ip rip events shows that only R1 route succeeds its entrance to rip database
In rip database only the best route is preserved
A debug ip routing on R2 shows that R3 route is not accepted by the routing table and returns code:19
As soon as we shutdown the lo13 interface on R1 the route gets poisoned and R3 route added
We bring up the lo13 interface on R1 and see that R3 route is removed because R2 receives now a better route metric from R1
In the R2 routing table the best protocol candidate route in terms of protocol metric (in our case hops) is added
The protocol metric is just copied to the structure the default routing table entry describing this route
This entry includes a new attribute that was not in the protocol table or database (rip database): distance (of 120 in case of RIP) which indicates the source of the route information
We configure static routing to the same destination and use a distance of 120
Now the static route is installed in the routing table
Not because of the administrative distance but rather the metric which is 0 for static routes
Static routing is a local routing information source to the router
It is different from dynamic routing because no routing information is exchanged between routers
Knowing that, why should I configure a metric for static routes?
Let’s add another static route to the same destination but that points the opposite direction
Both routes are installed because they have the same cost (metric)
In static routing metric and administrative distance are both local
There’s no case that may apply only to the metric in choosing the best route to put in the routing table
Using the metric in static routing is redundant
But the administrative distance is still needed to discriminate the routing information sources
Additionally, we could use different administrative distances per routes…