● Disable all physical interfaces on R1, R2, R3, R4, and R5, with the exception of their connections to the DMVPN cloud.
● Ensure that CDP is enabled on the DMVPN cloud between these devices and enable ODR on R5.
● Ensure that all DMVPN routers have IPv4 reachability to each other's Loopback0 prefixes.
Explanation
On-Demand Routing (ODR) uses Cisco Discovery Protocol (CDP) to advertise connected IPv4 routes of a stub router to the hub. The hub router then advertises a default IPv4 route back to the spokes via CDP.
For ODR to be functional, there should be no dynamic routing protocol configured on spokes. Assuming that the hub and spokes are already running CDP, the configuration of this feature requires only one command on the hub, router odr.
In this design, CDP is disabled on the mGRE Tunnel interface of all routers by default; therefore, the additional command cdp enable is required on all routers. Verify that spoke routers are CDP neighbors with the hub router, which is R5.
R1
show cdp neighbors tunnel0
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
show cdp neighbors tunnel0
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
R3
show cdp neighbors tunnel0
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
R4
show cdp neighbors tunnel0
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
R5
show cdp neighbors tunnel0
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay
Device ID Local Intrfce Holdtme Capability Platform Port ID
Total cdp entries displayed : 0
Verify that all spokes received the default route form the hub, and the hub has learned about the Loopback0 prefixes of spokes.
R1
show ip route odr | b Gateway
Gateway of last resort is 172.16.0.5 to network 0.0.0.0
o* 0.0.0.0/0 [160/1] via 172.16.0.5, 00:00:27, Tunnel0
R2
show ip route odr | b Gateway
Gateway of last resort is 172.16.0.5 to network 0.0.0.0
o* 0.0.0.0/0 [160/1] via 172.16.0.5, 00:00:34, Tunnel0
R3
show ip route odr | b Gateway
Gateway of last resort is 172.16.0.5 to network 0.0.0.0
o* 0.0.0.0/0 [160/1] via 172.16.0.5, 00:00:36, Tunnel0
R4
show ip route odr | b Gateway
Gateway of last resort is 172.16.0.5 to network 0.0.0.0
o* 0.0.0.0/0 [160/1] via 172.16.0.5, 00:00:38, Tunnel0
R5
show ip route odr | i 10.1.
10.1.0.0/32 is subnetted, 5 subnets
o 10.1.1.1 [160/1] via 172.16.0.1, 00:00:10, Tunnel0
o 10.1.2.2 [160/1] via 172.16.0.2, 00:00:12, Tunnel0
o 10.1.3.3 [160/1] via 172.16.0.3, 00:00:10, Tunnel0
o 10.1.4.4 [160/1] via 172.16.0.4, 00:00:10, Tunnel0
Verify IPv4 connectivity between Loopback0 prefixes.
R1
ping 10.1.2.2 source loopback0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.2.2, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
ping 10.1.3.3 source loopback0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.3.3, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/6 ms
ping 10.1.4.4 source loopback0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.4.4, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/8/31 ms
ping 10.1.5.5 source loopback0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.5.5, timeout is 2 seconds:
Packet sent with a source address of 10.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/3 ms
Verify that ODR is enabled on the hub, but not on the spokes.
R5
show ip protocols | section odr
Routing Protocol is "odr"
Sending updates every 60 seconds, next due in 52 seconds
Invalid after 180 seconds, hold down 0, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
