Technology: WAN
Area: DMVPN
Vendor: Cisco
Software: 12.X , 15.X ISR
Platform: ISR 1800, 2800, 3800, 1900, 2900, 3900, Platforms: 4300, 4400

Traffic Flow:

• Packet is sent from Spoke1 to Spoke2 network via Hub (according to routing table)
• Spoke1 has this prefix via HUB tunnel IP for which has also NHRP static mapping
• Hub routes packet to Spoke2 according to routing table via tunnel

DMVPN Phase 1 and EIGRP:

• Configure spokes as a stubs
• Advertise their connected routes
• Disable split horizon on hub (Spoke to Spoke prefix advertisement)
• Use next-hop self command (default)

HUB:
!
!
router eigrp 100
no auto-summary
network 20.1.0.0 0.0.255.255
network 172.16.2.0 0.0.0.255
!
! Tunnel source
!
interface Loopback0
ip address 30.159.1.1 255.255.255.0
!
! VPN network
!
interface Loopback 1
ip address 20.1.1.1 255.255.255.0
!
! mGRE tunnel
!
interface Tunnel0
ip address 172.16.1.1 255.255.255.0
no ip redirects
ip nhrp authentication av1labs
ip nhrp map multicast dynamic
ip nhrp network-id 111
no ip split-horizon eigrp 100
ip summary-address eigrp 100 20.0.0.0 255.0.0.0
tunnel source Loopback0
tunnel mode gre multipoint
tunnel key 123

Spokes Configuration example:

Traffic Flow:

• Packet is sent from Spoke A to Spoke B network via Hub (according to routing table)
• Spoke1 has this prefix via HUB tunnel IP for which has also NHRP static mapping
• Hub routes packet to Spoke2 according to routing table via tunnel

DMVPN Phase 1 and EIGRP:

• Configure spokes as a stubs
• Advertise their connected routes
• Disable split horizon on hub (Spoke to Spoke prefix advertisement)
• Use next-hop self command (default)

SPOKE A:
!
!
router eigrp 100
no auto-summary
network 172.16.1.0 0.0.0.255
network 20.1.2.0 0.0.0.255
eigrp stub connected
!
interface Loopback0
ip address 30.159.2.2 255.255.255.0
!
interface Loopback 1
ip address 20.1.2.2 255.255.255.0
!
! GRE tunnel
!
interface Tunnel0
ip address 172.16.1.2 255.255.255.0
ip nhrp authentication av1labs
ip nhrp map 172.16.1.1 30.159.1.1
ip nhrp map multicast 30.159.1.1
ip nhrp nhs 172.16.1.1
ip nhrp network-id 111
ip nhrp holdtime 60
ip nhrp registration timeout 30
tunnel source Loopback0
tunnel destination 30.159.1.1
tunnel key 123

SPOKE B:
!
!
router eigrp 100
no auto-summary
network 172.16.1.0 0.0.0.255
network 20.1.3.0 0.0.0.255
eigrp stub connected
!
interface Loopback0
ip address 30.149.3.3 255.255.255.0
!
interface Loopback 1
ip address 20.1.3.3 255.255.255.0
!
! GRE tunnel
!
interface Tunnel0
ip address 172.16.1.3 255.255.255.0
ip nhrp authentication av1labs
ip nhrp map 172.16.1.1 30.159.1.1
ip nhrp map multicast 30.159.1.1
ip nhrp nhs 172.16.1.1
ip nhrp network-id 111
ip nhrp holdtime 60
ip nhrp registration timeout 30
tunnel source Loopback0
tunnel destination 30.159.1.1
tunnel key 123