EIGRP summarization and Default Route

EIGRP supports summarization at the interface level anywhere throughout the topology






R2(config-if)#int f0/0
R2(config-if)#ip summary-address eigrp 100 2.2.2.0 255.255.248.0
01:53:34.283: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 12.1.1.1 (FastEthernet0/0) is resync: summary configured


Default Summary
R2(config-if)#ip summary-address eigrp 100 0.0.0.0 0.0.0.0

EIGRP Unicast Updates

EIGRP hello packets are sent to the multicast address 224.0.0.10, whereas topology synchronization between two neighbors is unicast. 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 is required to be configured on the other end as well.

Configuring neighbor command on one side will bring the adjacency down





configuring neighbor command on the other end will bring the adjacency up

EIGRP Multi-AF Mode

EIGRP Multi-AF Mode, also known as EIGRP Named Mode. The named mode is the new way of configuring EIGRP; this mode allows EIGRP configurations to be entered in a hierarchical manner under the router mode. 



#R2
router eigrp EIGRP-R2
 !
 address-family ipv4 unicast autonomous-system 100
  !
  topology base
  exit-af-topology
  network 1.1.1.0 0.0.0.255
  network 12.1.1.0 0.0.0.255
 exit-address-family
#R1
router eigrp EIGRP-R1
 !
 address-family ipv4 unicast autonomous-system 100
  !
  topology base
  exit-af-topology
  network 2.2.2.0 0.0.0.255
  network 12.1.1.0 0.0.0.255
 exit-address-family


EIGRP Wide Metric scaling is automatically enabled when EIGRP runs in Named Mode. This can be seen from the delay value now being measured in picoseconds in the EIGRP topology