DMVPN Configuration

Template Configuration:
## R1
int g1/0
ip address 122.1.1.1 255.255.255.0
no shut
duplex full
exit

## R2
int g1/0
ip address 122.1.1.2 255.255.255.0
no shut
duplex full
exit

## R3
int g1/0
ip address 122.1.1.3 255.255.255.0
no shut
duplex full
exit

conf t
int range f1/1 – 3
shutdown
no shutdown
exit

HUB:
interface tunnel 0
! IP address
ip address 10.0.0.1 255.255.255.0

! Bandwidth – Will be part of routing metrics
bandwidth 1000

! Ensures longer packets are fragmented before they are encrypted
ip mtu 1400

! The following line must match on all nodes that “want to use” this mGRE tunnel:
ip nhrp authentication donttell

! Note that the next line is required only on the hub
ip nhrp map multicast dynamic
Note: encapsulating multicast based on encapsulating unicast

! The following line must match on all nodes that want to use this mGRE tunnel:
ip nhrp network-id 99
ip nhrp holdtime 300

! Turns off split horizon on the mGRE tunnel interface; otherwise, EIGRP will not advertised routes that are learned vie the mGRE interface backout that interface.
no ip split-horizon eigrp 1

!
tunnel source g1/0
tunnel mode gre multipoint
tunnel key 100000

SPOKES:
SPOKES 1
int tunnel 0
ip address 10.0.0.2 255.255.255.0
!
ip nhrp authentication donttell

! Definition of NHRP server at the hub (10.0.0.1), which is permantly mapped to the static public address of the hub (122.1.1.1)..(left Private / Public address)
ip nhrp map 10.0.0.1 122.1.1.1

! Sends multicast packets to the hub router, and enables the use of a dynamic routing protocol between spoke and the hub.
ip nhrp map multicast 122.1.1.1

! The following line must match on all nodes that want to use this
ip nhrp network-id 99
ip nhrp holdtime 300

! Configures the hub router as the NHRP next-hop server
ip nhrp nbs 10.0.0.1
ip tcp adjust-mss 1360
delay 1000
tunnel source g1/0
tunnel destination 122.1.1.1
tunnel key 100000

SPOKES 2
int tunnel 0
ip address 10.0.0.3 255.255.255.0
ip nhrp authentication donttell
ip nhrp network-id 99
ip nhrp map 10.0.0.1 122.1.1.1
ip nhrp map multicast 122.1.1.1
ip nhrp nhs 10.0.0.1
tunnel source g1/0
tunnel destination 122.1.1.1
tunnel key 100000

Configuring Dynamic routing protocol:
! Configure on all Hub and spokes
router eigrp 1
network 10.0.0.0
network 192.168.0.0
no auto-summary

Troubleshooting:

EIGRP IS FLAPPING?
https://community.cisco.com/t5/switching/eigrp-continually-flapping/td-p/1811550
https://learningnetwork.cisco.com/thread/76634
https://community.cisco.com/t5/routing/random-eigrp-peer-termination-received-msgs/td-p/2055665
https://community.cisco.com/t5/switching/eigrp-flapping-retry-limit-exceeded/td-p/1925753

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s