EIGRP Notes

• To establish neighbor relationship, the neighbors MUST BE ON THE SAME SUBNET.
• EIGRP does support secondary addresses. But EIGRP always sources data packets from the primary address.
  • Configure all the routers on a particular subnet with the primary addresses that belong to the same subnet.
  • Routers will not form EIGRP neighbors over secondary networks.
• All the K values must be the same for all routers of AS# or there will be no neighbor relationship.
• Static routes are automatically advertised by EIGRP if next hop is interface and the interface is covered by the network statement. Need a distribute-list to prevent that.
• Split-horizon is always enabled by default on all EIGRP interfaces [including physicals].
• EIGRP Delays are the accumulation of outbound interfaces from source to destination.
• If 2 EIGRP domains are on same routers, they need to be redistributed manually into each other. It will not happen automatically.
• if EIGRP over ATM SVC: Add a neighbor statement in the EIGRP process, to convert from a multicast to a unicast [multicast will flap over ATM SVCs].