Doubt about simple static routing.

RouterOS General
1

Hi, i just made a lab from a book with gns3 about simple static routing, everything works well, but i don’t understand two of them.

RB_A
/ip route
add distance=1 dst-address=10.1.1.4/30 gateway=10.1.1.2
add distance=1 dst-address=10.1.1.8/30 gateway=10.1.1.2
add distance=1 dst-address=172.16.2.0/24 gateway=10.1.1.2
add distance=1 dst-address=172.16.3.0/24 gateway=10.1.1.2
add distance=1 dst-address=172.16.4.0/24 gateway=10.1.1.2

¿Why to use this routes if i don’t have them in any interface defined?, dst-address=10.1.1.4/30 gateway=10.1.1.2, dst-address=10.1.1.8/30 gateway=10.1.1.2.
Here is all the lab in a picture.


hosting imagenes

2

10.1.1.4/30 is on the link between RB_B and RB_C
10.1.1.8/30 is on the link between RB_C and RB_D

Both 10.1.1.4 and 10.1.1.8 are network addresses. In case of /30 it means:

10.1.1.4 - network address
10.1.1.5 - first usable address
10.1.1.6 - second usable address
10.1.1.7 - broadcast

If you had /29, it would be total 8 addresses, /28 would be 16, etc. And same ways as with /30, first is network address and last is broadcast.

3

Thanks friend, now I understand that part better.