Manual:Route lookup example

Route lookup example

Simple example:

[admin@MikroTik] > /ip address print
 #   ADDRESS            NETWORK         BROADCAST       INTERFACE
 0   10.1.0.3/16        10.0.0.0        10.1.255.255    ether1
 1   10.2.0.3/16        10.0.0.0        10.2.255.255    ether2

[admin@MikroTik] > /ip route print
 #      DST-ADDRESS        PREF-SRC        G GATEWAY         DISTANCE INTERFACE
 0 A S  0.0.0.0/0                          r 10.1.0.1        1        ether1
                                           r 10.2.0.1                 ether2
 1 ADC  10.1.0.0/16        10.1.0.3                          0        ether1
 2 ADC  10.2.0.0/16        10.2.0.3                          0        ether2

• Packet with destination address 10.1.1.1 will be forwarded using connected route (number 1) via interface ether1 to host with address 10.1.1.1.
• Packet with destination address 10.50.0.1 will be forwarded using static route (number 0) via interface ether1 to gateway 10.1.0.1, or via interface ether2 to gateway 10.2.0.1.
• Locally originated packet with destination address 10.100.0.1 will be sent using static route (number 0) via interface ether1 to gateway 10.1.0.1, or via interface ether2 to gateway 10.2.0.1.
• Locally originated packet with destination address 10.2.1.1 will be sent using connecter route (number 2) via interface ether2 to host with address 10.2.1.1 using source address 10.2.0.3.

If route does not have pref-src, then source address of locally originated packets is selected from local addresses of the router so that:

• this local address is assigned to the output interface
• gateway matches network of this local address

So, in the above example, if locally originated packet is sent to gateway 10.1.0.1, then local address 10.1.0.3 will be chosen, because

• address 10.1.0.3 is assigned to the output interface of this route (ether1)
• gateway 10.1.0.1 is inside the network 10.1.0.0/16 of this address