R1(config)#int FastEthernet0/0
R1(config-if)#ip address 1.1.1.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#exit
R1(config)#ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
R1(config)#end
R1#wr
Building configuration...
*Mar 1 00:15:23.571: %SYS-5-CONFIG_I: Configured from console by console[OK]
R1#
We then try to send a couple of pings from R1 and look at the ARP table:
R1#ping 2.2.2.2 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
.!!
Success rate is 66 percent (2/3), round-trip min/avg/max = 68/74/80 ms
R1#ping 3.3.3.3 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
.!!
Success rate is 66 percent (2/3), round-trip min/avg/max = 68/68/68 ms
R1#ping 4.4.4.4 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
.!!
Success rate is 66 percent (2/3), round-trip min/avg/max = 72/82/92 ms
R1#ping 5.5.5.5 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
.!!
Success rate is 66 percent (2/3), round-trip min/avg/max = 68/70/72 ms
R1#
R1#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 5.5.5.5 0 c002.28b4.0000 ARPA FastEthernet0/0
Internet 4.4.4.4 0 c002.28b4.0000 ARPA FastEthernet0/0
Internet 3.3.3.3 0 c002.28b4.0000 ARPA FastEthernet0/0
Internet 2.2.2.2 0 c002.28b4.0000 ARPA FastEthernet0/0
Internet 1.1.1.1 - c001.1b8c.0000 ARPA FastEthernet0/0
R1#
And here is the Wireshark packet capture during the ping test.
R1(config)#do show run int FastEthernet0/0 | inc interface|ip address
interface FastEthernet0/0
ip address 1.1.1.1 255.255.255.0
R1(config)#
R1(config)#no ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
R1(config)#ip route 0.0.0.0 0.0.0.0 1.1.1.2
R1(config)#
R1(config)#end
R1#
*Mar 1 00:26:12.919: %SYS-5-CONFIG_I: Configured from console by console
R1#
R1#clear arp-cache
R1#
R1#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 1.1.1.1 - c001.1b8c.0000 ARPA FastEthernet0/0
R1#
R1#ping 2.2.2.2 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
.!
Success rate is 50 percent (1/2), round-trip min/avg/max = 92/92/92 ms
R1#ping 3.3.3.3 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!
Success rate is 100 percent (2/2), round-trip min/avg/max = 64/66/68 ms
R1#ping 4.4.4.4 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!
Success rate is 100 percent (2/2), round-trip min/avg/max = 68/98/128 ms
R1#ping 5.5.5.5 re 2
Type escape sequence to abort.
Sending 2, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
!!
Success rate is 100 percent (2/2), round-trip min/avg/max = 60/86/112 ms
R1#
R1#show ip arp
R1#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 1.1.1.1 - c001.1b8c.0000 ARPA FastEthernet0/0
Internet 1.1.1.2 0 c002.28b4.0000 ARPA FastEthernet0/0
R1#
And here is the Wireshark capture during the ping test.
Internet#show run int fa0/0 | inc interface|ip address|proxy
interface FastEthernet0/0
ip address 1.1.1.2 255.255.255.0
no ip proxy-arp
R1#ping 2.2.2.2 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
...
Success rate is 0 percent (0/3)
R1#
R1#
R1#ping 2.2.2.2 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
...
Success rate is 0 percent (0/3)
R1#ping 3.3.3.3 re 3
Type escape sequence to abort.
Sending 3, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
...
Success rate is 0 percent (0/3)
R1#
R1#
R1#
R1#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 1.1.1.1 - c001.1b8c.0000 ARPA FastEthernet0/0
R1#
Have a question about something in this article? You can receive help directly from the article author. Sign up for a free trial to get started.
Comments (1)
Commented:
ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 1.1.1.2
This has all of the same benefits as routing to the next-hop address, but ensures that the traffic doesn't use another interface regardless of the routing table's data for the next hop. It also has other applications, such as statically leaking routes between VRF instances.
Good write-up.