EIGRP
Routing Algorithm
DUAL
calculates least cost loop-free routes
calculates backup routes
feasible successor
advertised distance (AD)
cost between the next-hop router and the destination
feasible distance (FD)
AD+cost between the local router and the next-hop router
Characteristics
Enhaced Interior Gateway Protocol
Distance Vector Routing Protocol
load-balance between 4 unequal cost routes
Transport Protocol
RTP
Reliable Transport Protocol
guaranteed ordered delivery and reception of EIGRP packets to all neighbors
Only IP
Network protocols supported
IP
IPX
AppleTalk
Cisco-proprietary
classless
routes are automatically summarized at the major network number boundary
partial triggered updates
updates are sent only when the path or the metric changes for a route
Subtema
commands
configuration
router eigrp <autonomous-system>
<autonomous system>
1-65536
Not related with AS number
MUST be equal in every router running eigrp on the network
network <network addr> <wildcard>
interfaces matching network addr and wildcard
will send eigrp updates
will appear in routing table
verification
show ip eigrp topology
all-links
you can see all the routes
routes that match feasible condition
routes that NOT match feasible condition
show routes that match feasible condition
feasible successor
backup route
show ip protocols
packets
Hello
Ethernet
multicast
Comparison with other Routing Protocols
Differences with RIP
Periodic updates
EIGRP has
partial
only send what changes
bounded
only send to who needs it
No backup routes
slow convergence
holddown timer
higher bandwidth utilization
Tables
Neighbor
next-hop
interface
Topology
includes feasible successors
Routing
(Externas) D EX
Administrative Distance = 170
i.e IGRP
Metric
parameters
bandwidth
reliability
0-255
delay
formula
k2*delay/(k1*bandwidth+k3*reliability)
default
k1=1
k2=1
k3=0
The lower the better
concepts
successor
best route
lowest FD
lowest cost
installed in routing table
up to 6 successors can exist if they have the same FD
feasible successor
backup route
next-hop router for a backup path
AD less than the FD of the current successor route
feasible condition
matched by
successor
feasible sucessors
route distance