Task:
● Load the Initial EIGRP configuration in your lab
● Configure EIGRP in Classic Mode on R1 - R4 using AS 100.
● Configure an EIGRP process named MULTI-AF on R5 using AS 100.
● Enable EIGRP on the DMVPN tunnel between these devices.
● Configure R4 and R5 so that they exchange EIGRP packets only as unicasts with each other on the DMVPN network.
Configuration:
R1-R3:
!
router eigrp 100
network 172.16.0.0 0.0.0.255
!
R4:
!
router eigrp 100
network 172.16.0.0 0.0.0.255
!
R5:
!
router eigrp MULTI-AF
!
address-family ipv4 unicast autonomous-system 100
!
topology base
exit-af-topology
network 172.16.0.0 0.0.0.255
exit-address-family
!
Verification:
By default, EIGRP hello packets are sent to the multicast address 224.0.0.10, whereas topology synchronization between two neighbors is unicast. Like RIP, the neighbor statement under the EIGRP process is used to send hello packets as unicasts.
However, unlike RIP, the passive-interface command is not needed to suppress the sending of the multicast hellos. This means that if the neighbor statement is configured on one end of the adjacency, it must also be configured on the other end.
Below we see that R5 has established EIGRP adjacency with R1 - R4
R5:
!
show eigrp address-family ipv4 100 neighbors
!
After the neighbor statement is configured on R5, all adjacencies are dropped because all multicast hellos are dropped. When R4 configures the neighbor statement as well, their adjacency is re-established:
R5:
!
configure terminal
router eigrp MULTI-AF
address-family ipv4 unicast autonomous-system 100
neighbor 172.16.0.4 tunnel0
!
R4:
!
configure terminal
router eigrp 100
neighbor 172.16.0.5 tunnel0
!
Because R5 is configured for unicast exchange on the DMVPN tunnel, adjacencies to all other spokes besides R4 are rejected. Basically, EIGRP cannot be enabled for both unicast and multicast over the same interface; thus, in this case, all received EIGRP multicast HELLO packets are ignored:
R5:
!
show eigrp address-family ipv4 100 neighbors
!
R5:
!
debug eigrp packet
!
