Transport – IP, protocol type 88 (does not use UDP or TCP) Implements its own Reliable Transport Protocol, providing reliable multicast and unicast packet delivery.
Metric – Based on the constrained bandwidth and cumulative delay by default, and optionally load reliability, and extended metrics
Hello Interval – Interval which a router sends EIGRP Hello messages on an interface
Hold timer – Timer used to determine when a neighboring router has failed, based on no longer receiving EIGRP messages during this timer period.
Update destination address – Normally sent to 224/0.0.10 or FF02::A with retransmissions unicasting to neighbor IP
Full or Partial updates – Full updates are used when discovering new EIGRP neighbors, all other updates are partial
Authentication – EIGRP supports MD5 and SHA
VLSM/Classless – EIGRP includes the subnet mask with each route allowing it to support discontiguous networks and VLSM.
Route Tags – Enables EIGRP to tag internal or external routes using route-maps, these routes can also be filtered based on tags using distribute lists.
Next-hop field – Supports advertisement of routes with a different next hop router.
Manual Route Summarization – allows route summarization at any point of a EIGRP network
Multiprotocol – Supports IPv4 and IPv6