The IT Stuff

EIGRP Summarization:

EIGRP Auto-summarization done when redistributing cannot be disabled.
EIGRP Auto-summarization done at class boundary and should be disabled with a “no auto-summary” when dealing with discontiguous networks.
EIGRP Will not automatically summarize external routes.
Automatic summarization can disabled using the following command:
Router(config-router)#no auto-summary
TO configure a summary route out a particular interface using the ip summary-address eigrp [...]

show ip route:  To inspect the routing table.
show ip route eigrp: To filter the routing table and show only the routes learned from EIGRP.
show ip protocols:  Verifies autonomous system, timer values, identified networks, and EIGRP neighbors (routing information sources).
show ip eigrp topology: Shows the EIGRP topology table and identifies successors and feasible successors.
show ip eigrp [...]

Cisco’s EIGRP  uses  metrics; Delay, Bandwidth, Reliability and Load. MTU is NOT used in the calculation of the metric, however the MTU is tracked through the path to find the smallest MTU.EIGRP only uses Delay and Bandwidth with Bandwidth taking precedence

Bandwidth
Delay
Reliability
Load

EIGRP Metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) + (K3*Delay)*(K5/(Reliability + K4)))
The k [...]

Maintaining a table of loop-free paths to every destination
DUAL saves all paths in the topology table.
Selects lowest cost , loop free paths to each destination
DUAL enables EIGRP routers to determine whether a path advertised by a neighbor is looped or loop-free, and allows a router running EIGRP to find alternate paths without waiting on [...]

Advance Distance vector Protocol
Support for IP, IPX, and AppleTalk via protocol-dependent modules
Considered classless (same as RIPv2 and OSPF)
Support for VLSM/CIDR, Discontigous Subnets
Support for summaries and discontiguous networks
Efficient neighbor discovery
Communication via Reliable Transport Protocol (RTP)
Best path selection via Diffusing Update Algorithm (DUAL)
Fast Convergence
Partial Updates
Flexible network design
100% Free Classless routing
easy [...]