1. EIGRP

2. EIGRP Topics EIGRP features EIGRP operation EIGRP metric
EIGRP load balancing
EIGRP configuration
EIGRP route summarization
EIGRP authentication

3. EIGRP Features Fast convergence Supports multiple protocols
Granular metric
Supports unequal costs load balancing
Supports VLSM
Flexible design/route summarization
Supports authentication

4. EIGRP Features Loop free Incremental updates Sends to multicast
Easy configuration

5. EIGRP Operation Advanced Distance Vector
Forms neighbor relationships before exchanging routing information
Maintains adjacency with hellos
every 5 seconds on LAN; 3 missed and neighbor considered dead
Neighbor information maintained in neighbor table
Passive-interface command prevents forming any adjacencies out that interface

6. EIGRP Operation Updates Full upon first exchange
Partial upon change in topology
Bounded
Reliably sent to
Acknowledged
Contain subnet mask
Summarizes at classful boundaries by default
Manual summarization at interfaces

7. EIGRP Route Selection
Metric calculated to destination is called Feasible Distance
Neighbor through which best feasible distance is calculated is called successor
Successor route or routes placed in routing table
Routes through other neighbors may qualify as feasible successor
Feasible successor routes maintained in topology table
Falls back to feasible successor instead of re-computing route
Diffusing Update Algorithm - DUAL

8. EIGRP Route Selection 150 B 45 55 120 192.168.1.0 A C E 45 180 D
Purpose: The figure shows how the IGRP commands operate on the example network.
Emphasize:
An administrator only specifies directly connected networks that he wishes to publish to other routers.
Without the network command, nothing is advertised. With a network command, the router will advertise every subnet within the Class A, B, or C network specified in the configuration. 45
180 D

9. EIGRP Composite Metric
19.2 kbps
19.2 kbps
Source
Destination
Purpose: This figure presents the IGRP metric with its five possible components.
Emphasize : Bandwidth and delay are the two metrics that are most commonly used. They also comprise the default metric.
Note:
Changing IGRP metrics can have great impact on network performance.
Describe the IGRP 24-bit metric field:
Bandwidth—Minimum bandwidth on the route in kilobits per second.
Delay—Route delay in tens of microseconds.
Reliability—Likelihood of successful packet transmission expressed as an integer from 0 to 255.
Loading—Effective bandwidth of path.
MTU—Minimum MTU in path, expressed in bytes.
The following equation calculates the metric. It is presented for instructors and is not required to be taught.
metric = [k1 * bandwidth + (k2 * bandwidth) / (256 - load) + k3 * delay]
If k5 does not equal 0, an additional operation is done:
metric = metric * (k5/(reliability + k4))
The default constant values are k1=k3=1 and k2=k4=k5=0.
Again, if default values are set, metric = bandwidth + delay.
The constants (k1, k2, k3) can be changed using the metric weights command. Changes to the IGRP constant values should be made with great care.
Bandwidth
Delay
Reliability
Loading
MTU

10. EIGRP Load Balancing Maximum six paths – default 4 equal paths
New Route
Source
Initial Route
Purpose: The figure presents how IGRP load sharing improves throughput and increases reliability.
Emphasize: Only feasible paths can be used for IGRP load sharing.
Load-balancing methods vary according to the switching mode because the data structures for process switching, fast switching, and autonomous switching are all different. When process switching, the processor load balances packet by packet. When fast, autonomous, or silicon switching, load balancing is done destination by destination.
By default, the amount of variance is set to one, which results in equal-cost load balancing.
You can use the default-metric command to change the default metric.
Transition: The following pages describe how to configure the IGRP routing protocol.
Destination
Maximum six paths – default 4 equal paths
Next-hop router closer to destination
Within metric variance – default is 1

11. EIGRP Load Balancing Router(config-router)#variance multiplier
Control EIGRP load balancing
Purpose:
This figure displays the commands to allow load sharing and load balancing in an IGRP environment.
Emphasize:
Note the router configuration mode to the students.

12. Configuring EIGRP Router(config)#router eigrp autonomous-system
Defines EIGRP as the IP routing protocol
Purpose: This figure explains how to use the router igrp and network commands to configure an IGRP process.
Emphasize: Note that the AS keyword is required for IGRP.
You can use multiple network commands to specify all networks that are to participate in the IGRP process. Only those networks specified will be published to other routers.
Router(config-router)#network network-number
Selects participating attached networks

13. EIGRP Configuration Example
Autonomous System = 100 E0 S2 S2 S3 S3 E0 A B C
router eigrp 100
network
network
router eigrp 100
network
network
Purpose: The figure shows how the IGRP commands operate on the example network.
Emphasize:
An administrator only specifies directly connected networks that he wishes to publish to other routers.
Without the network command, nothing is advertised. With a network command, the router will advertise every subnet within the Class A, B, or C network specified in the configuration.
router eigrp 100
network

14. Verifying the Routing Protocol—EIGRPS2 S2 S3 S3 E0 A B C
RouterA#sh ip protocols
Routing Protocol is "iegrp 100"
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 100
Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update
:01:01
Distance: (default is 90)
Purpose: This figure shows how the show ip protocol command is used to monitor IGRP operation.
Emphasize: The command displays the routing protocols that are active on the router for IP. It also gives network and timer information. In this example, IGRP is displayed.
Point out the timing information.
Point out the list of networks for which the router is injecting routes.
Point out the administrative distance metric.

15. EIGRP Show Commands show ip route eigrp show ip eigrp interfaces
show ip eigrp neighbors
show ip eigrp topology
show ip eigrp traffic