1. Must turn on CDP for all routers; hence this routing protocol is Cisco proprietary.

2. Only works in hub and spoke topology.

3. Has a default administrative distance of 160.

4. Extremely easy to configure.

5. Makes default route easier to configure for every spoke to hub communication. The hub router actually advertises default route to every spoke router using CDP.

R1 is the hub, the rest of the routers are spokes.

IP address parameters for all routers.

R1

interface FastEthernet0/0
 ip address 10.0.0.1 255.255.255.248
 duplex auto
 speed auto
end

interface Loopback1
 ip address 1.1.1.1 255.255.255.255
end
interface Loopback2
 ip address 2.2.2.2 255.255.255.255
end
interface Loopback3
 ip address 3.3.3.3 255.255.255.255
end

R2

interface FastEthernet0/0
 ip address 10.0.0.2 255.255.255.248
 duplex auto
 speed auto
end

R3

interface FastEthernet0/0
 ip address 10.0.0.3 255.255.255.248
 duplex auto
 speed auto
end

R4

interface FastEthernet0/0
 ip address 10.0.0.4 255.255.255.248
 duplex auto
 speed auto
end

Enable ODR routing, make sure cdp is turned on for every router

R1#sh run | s router
router odr
R1#

Routing table for all spoke routers

R2#sh ip route odr
o* 0.0.0.0/0 [160/1] via 10.0.0.1, 00:00:16, FastEthernet0/0
R2#

R3#sh ip route odr
o* 0.0.0.0/0 [160/1] via 10.0.0.1, 00:00:33, FastEthernet0/0
R3#

R4#sh ip route odr
o* 0.0.0.0/0 [160/1] via 10.0.0.1, 00:00:44, FastEthernet0/0
R4#

Reachability test for all spoke routers

R1 reaching int loopback192 of R2 and int loopback172 of R3

R1#ping 172.16.0.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/6/12 ms
R1#

R1#ping 192.168.0.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/5/8 ms
R1#

R2 reachability to int loopback1-3 of R1 and int loopback172 of R3

R2#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms
R2#ping 2.2.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms
R2#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/6/8 ms
R2#ping 172.16.0.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/8/12 ms
R2#

R3 reachability to R1,R2 loopback

R3#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms
R3#ping 2.2.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/9/16 ms
R3#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms
R3#ping 192.168.0.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/7/8 ms
R3#

R4 reachability to R1,2,3 loopback

R4#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms
R4#ping 2.2.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/8 ms
R4#ping 3.3.3.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
R4#ping 192.168.0.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/8/12 ms
R4#ping 172.16.0.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/9/16 ms
R4#