EIGRP
Enhanced Interior Gateway Routing Protocol (EIGRP) is a Cisco-proprietary
routing protocol for TCP/IP. It's actually based on Cisco's proprietary IGRP
routing protocol, with many enhancements built into it.
EIGRP has many link state characteristics that were added to it to allow for
greater scalability in enterprise networks.
EIGRP metrics
• Bandwidth
• Load
• Delay
• Reliability
• MTU
• Hop Count
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Successor
A successor for a particular destination is a next hop router that
satisfies these two conditions:
1. It provides the least distance to that destination
2. It is guaranteed not to be a part of a routing loop
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Feasible Successor
A feasible successor provides a working route to the same destination,
although with a higher distance.
A feasible successor for a particular destination is a next hop router
that satisfies this condition:
1. It is guaranteed not to be a part of a routing loop
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Active and Passive State
A destination in the topology table can be marked either as Passive or
Active.
A Passive state is a state when the router has identified the
successor(s) for the destination.
Active state is a state where the current successor no longer satisfies
the Feasibility Condition and there are no feasible successors identified
for that destination (i.e. no backup routes are available).
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Features of EIGRP
• EIGRP supports Classless Inter-Domain Routing (CIDR)
• EIGRP is not usable in applications where routers need to know the
exact network topology
• EIGRP can run separate routing processes for Internet Protocol (IP),
IPv6 etc
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Useful OSPF Commands (Cisco IOS)
Commands
Descriptions
Router(config)#router eigrp 1
Turns on the EIGRP process. 1 is the autonomous system
number, which can be a number between 1 and 65,535.
Note:- All routers in the same autonomous system must use the same autonomous system number.
Router(config-router)#network 10.0.0.0
Specifies which network to advertise in EIGRP.
Router(config-if)#bandwidth x
Sets the bandwidth of this interface to x kilobits to allow
EIGRP to make a better metric calculation
TIP: The bandwidth command is used for metric calculations only. It does not change interface performance.
Router(config-router)#no network 10.0.0.0
Removes the network from the EIGRP process.
Router(config)#no router eigrp 1
Disables routing process 1
Router(config-router)#auto-summary
Enables auto-summarization for the EIGRP process.
Router(config-router)#no autosummary
Turns off the auto-summarization feature.
Router(config-router)#variance n
include routes with a metric less than or equal to n times
the minimum metric route for that destination, where n is
the number specified by the variance command
NOTE: If a path is not a feasible successor, it is not used in load balancing. EIGRP supports up to six unequal-cost paths.
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Useful OSPF Commands (Cisco IOS) CONTD.
Commands
Descriptions
Router(config)#interface serial 0/0
Enters interface configuration mode.
Router(config-if)#bandwidth 256
Sets the bandwidth of this interface to 256 kilobits to
allow EIGRP to make a better metric calculation.
Router#show ip eigrp neighbors
Displays the neighbor table.
Router#show ip eigrp neighbors detail
Displays a detailed neighbor table.
Router#show ip eigrp interfaces
Shows information for each interface
Router#show ip eigrp interfaces serial 0/0
Shows information for a specific interface
Router#show ip eigrp interfaces 1
Shows information for interfaces running process 1.
Router#show ip eigrp topology
Displays the topology table
Router#show ip eigrp traffic
Shows the number and type of packets sent and
received
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Hands On Lab – Setup EIGRP on All R1,2 and 3
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Further Reading
1. http://computernetworkingnotes.com/routing-static-dynamics-ripospf-igrp-eigrp/eigrp-routing-configurations.html
2. http://cs-study.blogspot.com/2012/10/eigrp-on-packet-tracer.html
3. http://en.wikipedia.org/wiki/Enhanced_Interior_Gateway_Routing_
Protocol
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Questions?
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