1. Overview
2. Characteristics
   1. Network Type
      1. Internal routes are those injected into EIGRP by the network command (AD 90)
      2. External routes are redistributed into EIGRP from a different routing source (AD 170)
   2. Metric
      1. Bandwidth (in kbps)
      2. Delay (tens of microseconds)
      3. Reliability (ratio good frame/total frame 1-255)
      4. Load (ratio traffic/capacity 1-255)
      5. Throughput (65536×10^7/If BW)
      6. Latency (65536×If Delay/10^6)
      7. MTU
      8. Hop Count
      9. Formulas
         1. Classic Composite Metric
         2. Wide Metrics
   3. Packet Format
      1. carried directly in IP packets, using protocol number 88
3. Packets
   1. Hello (Default 5s, NBMA 60s)
   2. Acknowledgment (ACK)
   3. Update (Opcode 1)
   4. Query (Opcode 3)
   5. Reply (Opcode 4)
   6. SIA-Query (Opcode 10)
   7. SIA-Reply (Opcode 11)
   8. Reliable Transport Protocol (RTP)
      1. Manages the delivery and reception of EIGRP packets
      2. Assure delivery of Multicast and Unicast Packets
      3. Carry a nonzero Sequence number in its header
      4. Conditional Receive
4. CLI
   1. show ip eigrp traffic
   2. show ip eigrp neighbors
      1. H
      2. Address
      3. Interface
      4. Hold
      5. Uptime
      6. SRTT - Smooth Round Trip Time
      7. RTO - Retransmission Time Out
      8. Q Cnt
      9. Seq Num
   3. ip hello-interval eigrp {as-num} {sec}
   4. ip hold-time eigrp {as-num} {sec}
5. Router Adjacencies
   1. Adjacency Creation Process
   2. Discovery
      1. Multicast Hellos
         1. FF02::A
         2. 224.0.0.10
      2. Unicast Hellos
         1. Static Neighbor through neighbor command
   3. Neighbor Parameters Agreement
      1. EIGRP K-Values
      2. EIGRP Autonomous System (AS) Number
      3. Use of primary addresses for EIGRP neighbor relationships
      4. Use of the common IP network address on a single subnet
      5. EIGRP Authentication Parameters (if configured)
   4. Timers
      1. Hold Time (3x Hello Timers)
      2. Hello Time (5sec. / NBMA 60sec.)
   5. Neighbor Table
6. Diffusing Update Algorithm
   1. Topology table
      1. Contain all EIGRP routing information
      2. Network are in Active or Passive State
   2. Feasible Distance
   3. Reported Distance
   4. Feasible Successor
   5. Metric : 256 * [(10⁷ / slowest-bandwidth) + cumulative-delay] (default K)
7. External links
   1. Introduction to EIGRP
   2. Enhanced Interior Gateway Routing Protocol
   3. wikipedia/EIGRP
   4. DocWiki