EIGRP

Instructor Materials
Chapter 6: EIGRP
CCNA Routing and Switching
Scaling Networks v6.0

2© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
 This PowerPoint deck is divided in two parts:
 Instructor Planning Guide
• Information to help you become familiar with the chapter
• Teaching aids
 Instructor Class Presentation
• Optional slides that you can use in the classroom
• Begins on slide # 13
 Note: Remove the Planning Guide from this presentation before sharing with anyone.
Instructor Materials – Chapter 6 Planning Guide

Chapter 6: EIGRP
Scaling Networks v6.0 Planning Guide

What activities are associated with this chapter?
Chapter 6: Activities
Page # Activity Type Activity Name Optional?
6.0.1.2 Class Activity Classless EIGRP Optional
6.1.2.5 Interactive Activity Identify the EIGRP Packet Type Recommended
6.1.2.6 Video Observing EIGRP Protocol Communications Recommended
6.2.1.5 Syntax Checker Configuring the EIGRP Router ID Recommended
6.2.1.7 Syntax Checker Configuring the Network Command and Wildcard Mask Recommended
6.2.1.8 Syntax Checker EIGRP Passive Interface Recommended
6.2.2.4 Packet Tracer Configuring Basic EIGRP with IPv4 Recommended
6.2.2.5 Lab Configuring Basic EIGRP with IPv4 Optional
6.3.1.4 Interactive Activity Identify the Steps in Establishing EIGRP Neighbor Adjacencies Recommended
6.3.2.7 Interactive Activity Calculate the EIGRP Metric Recommended
The password used in the Packet Tracer activities in this chapter is: PT_ccna5

What activities are associated with this chapter?
Chapter 6: Activities Cont.)
Page # Activity Type Activity Name Optional?
6.3.3.8 Interactive Activity Determine the Feasible Successor Recommended
6.3.4.4 Packet Tracer Investigating DUAL FSM Optional
6.4.1.4 Interactive Activity Compare EIGRPv4 and EIGRPv6 Recommended
6.4.2.2 Syntax Checker Configuring IPv6 Link-local Address Recommended
6.4.2.3 Syntax Checker Configuring the EIGRP for IPv6 Routing Process Recommended
6.4.2.4 Syntax Checker Enable EIGRP for IPv6 on the Interface Recommended
6.4.3.4 Packet Tracer Configuring Basic EIGRP with IPv6 Recommended
6.4.3.5 Lab Configuring Basic EIGRP with IPv6 Optional
6.5.1.1 Class Activity Portfolio RIP and EIGRP Optional
The password used in the Packet Tracer activities in this chapter is: PT_ccna5

 Students should complete Chapter 6, “Assessment” after completing Chapter 6.
 Quizzes, labs, Packet Tracers and other activities can be used to informally assess student
progress.
Chapter 6: Assessment

Prior to teaching Chapter 6, the instructor should:
 Complete Chapter 6, “Assessment.”
 Understand the objectives of this chapter are:
• Explain how EIGRP operates in a small to medium-sized business network.
• Implement EIGRP for IPv4 in a small to medium-sized business network.
 Ensure this chapter becomes as hands-on as possible.
Chapter 6: Best Practices

 Review the classification of routing protocols – interior, exterior, distance vector and link state –
where does EIGRP fit?
 Identify stress advantages of EIGRP as an advanced distance vector protocol:
• Triggered updates
• Bounded updates
• Partial updates
 Backup routes – feasible successors
 Outline the EIGRP packet types – Hello, Update, Query, and Reply, focusing on Hello and Update.
• The reserved EIGRP multicast address for IPv4 is 224.0.0.10.
• The reserved EIGRP multicast address for IPv6 is FF02::A.
 Present the method used to compute the EIGRP metric emphasizing that bandwidth and delay are
primary – other components set to 0.
 Explain DUAL as the convergence algorithm used by EIGRP.
Chapter 6: Best Practices (Cont.)

 Highlight the three tables used by EIGRP:
• Neighbor (show ip eigrp neighbors)
• Topology (show ip eigrp topology)
• Routing (show ip route)
 Emphasize the importance of the topology table entries
• Successor and Feasible Successor
• Passive and Active
 Explain FD, RD, and FC
 Demonstrate how to configure EIGRP for ipv4
• Using the router eigrp autonomous-system command
• Verifying that directly connected networks and wildcard masks are configured

 To calculate the wildcard mask (also known as the inverse of the subnet mask):
• 255.255.255.255
• - 255.255.255.248 subnet mask
• 0. 0. 0. 7 wildcard mask
 Demonstrate how EIGRP for IPv6 configuration differs from IPv4:
• IPv6 routing protocols use link-local addresses for unicast addressing and next-hop addresses and are,
therefore, manually configured.
• The ipv6 unicast-routing command must be configured to allow routing.
• Use the ipv6 router eigrp autonomous-system command to enable EIGRP.
• The no shutdown command is required to activate EIGRP for the IPv6 process.
 Different methods to enable an interface for EIGRP IPv6:
• Instead of using the network command, EIGRP for IPv6 is configured directly on the interface using the
ipv6 eigrp interface command.
• Use the show ipv6 protocols command to verify the configuration.

 For additional help with teaching strategies, including lesson plans, analogies for difficult concepts,
and discussion topics, visit the CCNA Community at:
https://www.netacad.com/group/communities/community-home
 Best practices from around the world for teaching CCNA Routing and Switching.
https://www.netacad.com/group/communities/ccna
 If you have lesson plans or resources that you would like to share, upload them to the CCNA
Community in order to help other instructors.
 Students can enroll in Introduction to Packet Tracer (self-paced)
Chapter 6: Additional Help

Chapter 6: EIGRP
CCNA Routing and Switching
Scaling Networks v6.0

 6.1 EIGRP Characteristics
• Explain the features and characteristics of EIGRP.
• Describe the basic features of EIGRP.
• Describe the types of packets used to establish and maintain an EIGRP neighbor adjacency.
• Describe the encapsulation of an EIGRP messages.
 6.2 Implement EIGRP for IPv4
• Configure EIGRP for IPv4 in a small routed network.
• Verify EIGRP for IPv4 operation in a small routed network.
Chapter 6 - Sections & Objectives

 6.3 EIGRP Operation
• Explain how EIGRP operates in a small to medium-sized business network.
• Explain how EIGRP forms neighbor relationships.
• Explain the metrics used by EIGRP.
• Explain how DUAL operates and uses the topology table.
• Describe events that trigger EIGRP updates.
 6.4 Implement EIGRP for IPv6
• Compare characteristics and operation of EIGRP for IPv4 to EIGRP for IPv6.
• Configure EIGRP for IPv6 in a small routed network.
• Verify EIGRP for IPv6 implementation in a small routed network.
Chapter 6 - Sections & Objectives (Cont.)

6.1 EIGRP Characteristics

 Enhanced IGRP is a Cisco-proprietary distance-vector routing protocol released in 1992.
• EIGRP was created as a classless version of IGRP.
• Ideal choice for large, multiprotocol networks built primarily on Cisco routers.
EIGRP Characteristics
EIGRP Basic Features
EIGRP Feature Description
Diffusing Update Algorithm
(DUAL)
• EIGRP uses DUAL as its routing algorithm.
• DUAL guarantees loop-free and backup paths throughout the routing domain.
Establishing Neighbor
Adjacencies
• EIGRP establishes relationships with directly connected EIGRP routers.
• Adjacencies are used to track the status of these neighbors.
Reliable Transport
Protocol
• EIGRP RTP provides delivery of EIGRP packets to neighbors.
• RTP and neighbor adjacencies are used by DUAL.
Partial and Bounded
updates
• Instead of periodic updates, EIGRP sends partial triggered updates when a path or metric changes.
• Only those routers that require the information are updated minimizing bandwidth use.
Equal and Unequal Cost
Load Balancing
• EIGRP supports equal cost load balancing and unequal cost load balancing, which allows
administrators to better distribute traffic flow in their networks.

 EIGRP uses protocol-dependent modules (PDMs) to support different protocols such as IPv4, IPv6,
and legacy protocols IPX and AppleTalk.
 PDMs are responsible for:
• Maintaining EIGRP neighbor and topology tables
• Computing the metric using DUAL
• Interfacing DUAL and routing table
• Implementing filtering and access lists
• Performing redistribution with other routing protocols
EIGRP maintains individual tables for each routed protocol.

 RTP is the EIGRP Transport layer protocol used for the delivery and reception of EIGRP packets.
 Not all RTP packets are sent reliably.
• Reliable packets require explicit
acknowledgement from destination
• Update, Query, Reply
• Unreliable packets do not require
acknowledgement from destination
• Hello, ACK

 EIGRP supports authentication
and is recommended.
• EIGRP authentication ensures
that routers only accept routing
information from other routers that
have been configured with the
same password or authentication
information.
 Note:
• Authentication does not encrypt
the EIGRP routing updates.

 IP EIGRP relies on 5 types of packets to maintain its various tables and establish complex
relationships with neighbor routers.
EIGRP Packet Types

 Hello packets are used to
discover & form adjacencies
with neighbors.
• On hearing Hellos, a router
creates a neighbor table and the
continued receipt of Hellos
maintains the table.
 Hello packets are always sent
unreliably.
• Therefore Hello packets do not
require acknowledgment.
EIGRP Packet Types
EIGRP uses multicast and unicast rather than broadcast.
• As a result, end stations are unaffected by routing updates or queries.
• The EIGRP multicast IPv4 address is 224.0.0.10
• The EIGRP multicast IPv6 address is FF02::A.

 EIGRP Update packets are used to
propagate routing information.
• Sent to initially exchange topology
information or topology change.
• EIGRP updates only contain needed
routing information and are unicast to
routers that require it.
• Update packets are sent reliably and
therefore requires acknowledgements.
EIGRP Packet Types
 Acknowledgements packets are “dataless” Hello packets used to indicate receipt of any
EIGRP packet during a "reliable" (i.e., RTP) exchange.
• Used to acknowledge the receipt of Update packets, Query packets, and Reply packets.

 Query and reply packets are used by
DUAL when searching for networks.
 They both use reliable delivery and
therefore require acknowledgement.
 Queries can use multicast or unicast,
whereas Replies are always sent as
unicast.
EIGRP Packet Types

EIGRP Packet Types

 EIGRP frame contains destination multicast
address 01-00-5E-00-00-0A.
 The IP packet header contains destination IP
address 224.0.0.10 and identifies this packet as
an EIGRP packet (protocol 88).
 The data portion of the EIGRP message includes:
• Packet header - The EIGRP packet header
identifies the type of EIGRP message.
• Type/Length/Value (TLV) - The TLV field contains
EIGRP parameters, IP internal and external routes.
 EIGRP for IPv6 is encapsulated using an IPv6
header with multicast address FF02::A and the
next header field set to protocol 88.
EIGRP Messages

 EIGRP messages include the header with an
Opcode field that specifies the type of EIGRP
packet (Hello, Ack, Update, Query, and Reply)
and the AS number field.
EIGRP Messages
EIGRP TLV: External RoutesEIGRP TLV: Internal RoutesEIGRP TLV: EIGRP Parameters

6.2 Implement EIGRP for IPv4

 The routers in the topology have a starting configuration that includes addresses on the interfaces.
There is currently no static routing or dynamic routing configured on any of the routers.
Implement EIGRP for IPv4
Configure EIGRP with IPv4

 An Autonomous System (AS) is a collection of
networks under the control of a single authority
(reference RFC 1930).
• AS numbers are needed to exchange routes
between AS.
• AS numbers are managed by IANA and assigned
by RIRs to ISPs, Internet Backbone providers,
and institutions connecting to other institutions
using AS numbers.
 AS numbers are usually 16-bit numbers, ranging from 0 to 65535.
• Since 2007, AS numbers can now be 32 bits, therefore increasing the number of AS numbers
to over 4 billion.

 To configure EIGRP, use the router eigrp AS-# command.
• The AS-# functions as a process ID.
• The AS number used for EIGRP configuration is only significant to the EIGRP routing domain.
• All routers in the EIGRP routing domain must use the same AS number (process ID number).
 Note:
• Do NOT configure multiple instances of EIGRP on the same router.

 The EIGRP router ID is used to
uniquely identify each router in the
EIGRP routing domain.
 Routers use the following three
criteria to determine its router ID:
1. Use the address configured with
the eigrp router-id ipv4-
address router config command.
2. If the router ID is not configured,
choose the highest IPv4 address of
any of its loopback interfaces.
3. If no loopback interfaces are
configured, choose the highest
active IPv4 address of any of its
physical interfaces.

 Use the network network-number [wildcard-mask] router config command to enable and advertise
a network in EIGRP.
• It enables the interfaces configured for that network address to begin transmitting & receiving EIGRP
updates
• Includes network or subnet in EIGRP updates

 A wildcard mask is similar to a subnet mask but is calculated by subtracting a SNM from
255.255.255.255.
 For example, if the SNM is 255.255.255.252:
• 255.255.255.255
• - 255.255.255.252
• 0. 0. 0. 3 Wildcard mask
 EIGRP also automatically converts a subnet
mask to its wildcard mask equivalent.
• E.g., entering 192.168.10.8 255.255.255.252
automatically converts to 192.168.10.8 0.0.0.3

 Passive interfaces prevent EIGRP updates out a specified router interface.
 Set a particular interface or all router interfaces to passive.
• The default option sets all router interfaces to passive.
• Prevents neighbor relationships from being established.
• Routing updates from a neighbor are ignored.
Router(config-router)#
passive-interface type number [default]

 Use the show ip eigrp neighbors command to view the neighbor table and verify that EIGRP has
established an adjacency with its neighbors.
• The output displays a list of each adjacent neighbor.
Verify EIGRP with IPv4

 The show ip protocols command is useful to
identify the parameters and other information about
the current state of any active IPv4 routing protocol
processes configured on the router.
 For example, in the command output in the figure:
1. EIGRP is an active dynamic routing protocol on R1
configured with the autonomous system number 1.
2. The EIGRP router ID of R1 is 1.1.1.1.
3. The EIGRP administrative distances on R1 are internal
AD of 90 and external of 170 (default values).
4. By default, EIGRP does not automatically summarize
networks. Subnets are included in the routing updates.
5. The EIGRP neighbor adjacencies R1 has with other
routers used to receive EIGRP routing updates.

6.3 EIGRP Operation

1. Router R1 starts has joined the EIGRP routing
domain and sends an EIGRP Hello packet out
all EIGRP enabled interfaces.
2. Router R2 receives the Hello packet and adds
R1 to its neighbor table.
• R2 sends an Update packet that contains all
the routes it knows.
• R2 also sends an EIGRP Hello packet to R1.
3. R1 updates its neighbor table with R2.
EIGRP Operation
EIGRP Initial Route Discovery
 After both routers have exchanged Hellos, the neighbor adjacency is established.

1. R1 adds all update entries from R1 to its topology
table.
• The topology table includes all destinations
advertised by neighboring (adjacent) routers and
the cost (metric) to reach each network.
EIGRP Operation
2. EIGRP update packets use reliable delivery; therefore, R1 replies with an EIGRP
acknowledgment packet informing R2 that it has received the update.
3. R1 sends an EIGRP update to R2 advertising the routes that it is aware of, except those learned
from R2 (split horizon).
4. R2 receives the EIGRP update from R1 and adds this information to its own topology table.
5. R2 responds to R1’s EIGRP update packet with an EIGRP acknowledgment.

1. R1 uses DUAL to calculate the best routes to each
destination, including the metric and the next-hop
router and updates its routing table with the best
routes.
2. Similarly, R2 uses DUAL and updates its routing
table with the best newly discovered routes.
EIGRP Operation
 At this point, EIGRP on both routers is considered to be in the converged state.

 EIGRP uses a composite metric which can be based on the following metrics:
• Bandwidth: The lowest bandwidth between source and destination.
• Delay: The cumulative interface delay along the path
• Reliability: (Optional) Worst reliability between source and destination.
• Load: (Optional) Worst load on a link between source and destination.
EIGRP Operation
EIGRP Metrics
Note.
• It is often incorrectly
stated that EIGRP can
also use the smallest
MTU in the path.
 The EIGRP composite metric formula
consists metric weights with values K1 to K5.
• K1 represents bandwidth, K3 delay, K4 load,
and K5 reliability.

 Use the show interfaces command to
examine the values used for bandwidth,
delay, reliability, and load.
EIGRP Operation
EIGRP Metrics
• BW - Bandwidth of the interface (in kb/s).
• DLY - Delay of the interface (in microseconds).
• Reliability - Reliability of the interface as a
fraction of 255 (255/255 is 100% reliability).
• Txload, Rxload - Transmit and receive load on
the interface as a fraction of 255 (255/255 is
completely saturated), calculated as an
exponential average over five minutes.

 Use the following interface configuration mode
command to modify the bandwidth metric:
• Router(config-if)# bandwidth kilobits-bandwidth-value
 Use the show interfaces command to verify the new
bandwidth parameters.
EIGRP Operation
EIGRP Metrics

 Delay is a measure of the time it takes for a packet to
traverse a route.
 The delay (DLY) metric is not measured dynamically.
• It is a static value measured in microseconds (μs or usec)
based on the type of link to which the interface is connected.
 The delay value is calculated using the cumulative (sum) of
all interface delays along the path, divided by 10.
EIGRP Operation
EIGRP Metrics
Media
Delay
In usec
Gigabit Ethernet 10
Fast Ethernet 100
FDDI 100
16M Token Ring 630
Ethernet 1,000
T1 (Serial Default) 20,000
DS0 (64 Kbps) 20,000
1024 Kbps 20,000
56 Kbps 20,000

 We can determine the EIGRP metric as follows:
1. Determine the link with the slowest bandwidth and
use that value to calculate bandwidth
(10,000,000/bandwidth).
2. Determine the delay value for each outgoing
interface on the way to the destination and add the
delay values and divide by 10 (sum of delay/10).
3. This composite metric produces a 24-bit value which
EIGRP multiplies with 256.
EIGRP Operation
EIGRP Metrics

 How does EIGRP determine the following metric?
EIGRP Operation
EIGRP Metrics
 Bandwidth = 10,000,000 / slowest bandwidth
 Bandwidth = 10,000,000 / 1024 = 9765
 Delay = (Sum of all delays) / 10
 Delay = (20,000 + 10) / 1024 = 2001
 EIGRP Composite Metric = (9765 + 2001) x 256 = 3,012.096
 EIGRP Composite Metric = (Bandwidth + Delay) x 256

 EIGRP uses the Diffusing Update Algorithm (DUAL) to provide the best and backup loop-free paths.
 DUAL uses several terms, which are discussed in more detail throughout this section:
EIGRP Operation
DUAL and the Topology Table
Term Description
Successor
• Is a neighboring router that is used for packet forwarding and is the least-cost route to the destination network.
• The IP address of a successor is shown in a routing table entry right after the word “via”.
Feasible
Successors (FS)
• These are the “Backup paths” that are a loop-free.
• Must comply to a feasibility condition.
Reported
Distance (RD)
• Also called “advertised distance”, this is the reported metric from the neighbor advertising the route.
• If the RD metric is less than the FD, then the next-hop router is downstream and there is no loop.
Feasible
Distance (FD)
• This is the actual metric of a route from the current router.
• Is the lowest calculated metric to reach the destination network.
• FD is the metric listed in the routing table entry as the second number inside the brackets.

 Routing loops, even temporary ones, can be detrimental to network performance and EIGRP
prevents routing loops with the DUAL algorithm.
• The DUAL algorithm is used to obtain loop-freedom at every instance throughout a route computation.
 The decision process for all route computations is done by the DUAL Finite State Machine (FSM).
An FSM is a workflow model, similar to a flow chart, which is composed of the following:
• A finite number of stages (states)
• Transitions between those stages
• Operations
 The DUAL FSM tracks all routes and uses EIGRP metrics to select efficient, loop-free paths, and to
identify the routes with the least-cost path to be inserted into the routing table.
EIGRP Operation

 A successor is a neighboring router with the least-
cost route to the destination network.
• The successor IP address is shown right after “via”.
 FD is the lowest calculated metric to reach the
destination network.
• FD is the second number inside the brackets.
• Also known as the “metric” for the route.
 Notice that EIGRP’s best path for the
192.168.1.0/24 network is through router R3, and
that the feasible distance is 3,012,096.
EIGRP Operation

 DUAL converges quickly because it can use backup paths
known as Feasible Successors (FSs).
 A FS is a neighbor with a loop-free backup path to the
same network as the successor.
• A FS must satisfy the Feasibility Condition (FC).
• The FC is met when a neighbor’s Reported Distance (RD) is
less than the local router’s feasible distance.
• If the reported distance is less, it represents a loop-free path.
 E.g., the RD of R1 (2,170,112) is less than R2’s own FD
(3,012,096) and therefore, R1 meets the FC and becomes
the FS for R2 to the 192.168.1.0/24 network.
EIGRP Operation

 Topology table stores the following information required by
DUAL to calculate distances and vectors to destinations.
• The reported distance (RD) that each neighbor advertises
for each destination
• The feasible distance (FD) that this router would use to
reach the destination via that neighbor.
 Use the show ip eigrp topology command to list all
successors and FSs to destination networks.
• Only the successor is installed into the IP routing table.
• Passive State - Route is in stable state and available for use.
• Active State - Route is being recomputed by DUAL.
EIGRP Operation

 The first line in the topology table displays:
• P - Route in the passive state (the route is in a stable
mode). If DUAL recalculates or searches for a new path,
the route is in an active state and displays an A.
• 192.168.1.0/24 - Destination network is also found in the
routing table.
• 1 successors - Displays the number of successors for this
network. If there are multiple equal cost paths to this
network, there are multiple successors.
• FD is 3012096 - FD, the EIGRP metric to reach the
destination network. This is the metric displayed in the IP
routing table.
EIGRP Operation

 The partial output of the show ip route command displays
the 192.168.1.0/24 route with the successor is R3 via
192.168.10.6 with an FD of 2,170,112.
 The show ip eigrp topology command only shows the
successor 192.168.10.6, which is R3.
• Notice there are no FSs.
 The show ip eigrp topology all-links command shows all
possible paths to a network, including successors, FSs,
and even those routes that are not FSs.
EIGRP Operation

 The DUAL Finite State Machine (FSM)
contains all of the logic used to
calculate and compare routes in an
EIGRP network.
 An FSM is an abstract machine, that
defines a set of possible states that
something can go through, what events
cause those states, and what events
result from those states.
• Designers use FSMs to describe how a
device, computer program, or routing
algorithm reacts to a set of input events.
EIGRP Operation
DUAL and Convergence

 IP EIGRP
EIGRP Operation

 If the path to the successor fails and there are no FSs, DUAL puts the network into the active state
and actively queries its neighbors for a new successor.
• DUAL sends EIGRP queries asking other routers for a path to the network.
• Other routers return EIGRP replies, letting the sender of the EIGRP query know that they have a path to
the requested network. If there is no reply, the sender of the query does not have a route to this network.
• If the sender receives EIGRP replies with a path to the requested network, the preferred path is added
as the new successor and also added to the routing table.
EIGRP Operation

EIGRP Operation

6.4 Implement EIGRP for IPv6

EIGRP for IPv6
 EIGRP for IPv6 is a distance-vector
routing protocol.
• The configuration and operation is
similar to EIGRP for IPv4.
 The following remained the same as
EIGRP for IPv4:
• Uses the same protocol number (88)
• Maintains a topology table and
queries if no feasible successors are
available.
• Uses DUAL to calculate the successor
routes

 The following compares EIGRP for IPv4 and IPv6
EIGRP for IPv6

EIGRP for IPv6
 EIGRP for IPv6 messages are
sent using:
• Source IPv6 address - This is
the IPv6 link-local address of
the exit interface.
• Destination IPv6 address -
When the packet needs to be
sent to a multicast address, it
is sent to the IPv6 multicast
address FF02::A, the all-
EIGRP-routers with link-local
scope. If the packet can be
sent as a unicast address, it is
sent to the link-local address of
the neighboring router.

Configure EIGRP for IPv6

 The ipv6 unicast-routing global config mode
command enables IPv6 routing on the router.
 Use the ipv6 router eigrp autonomous-system to
enter EIGRP for IPv6 router configuration mode.
 Use the eigrp router-id router-id command is
used to configure the router ID.
 By default, the EIGRP for IPv6 process is in a
shutdown state and the no shutdown command
is required to activate the EIGRP for IPv6 process.

 Unlike EIGRP for IPv4 which uses the network command, EIGRP for IPv6 is configured directly on
the interface using the ipv6 eigrp autonomous-system interface configuration command.
The same passive-interface command
used for IPv4 is used with EIGRP for IPv6.

Verifying EIGRP for IPv6
 Use the show ipv6 eigrp neighbors command to view the neighbor table and verify that EIGRP for
IPv6 has established an adjacency with its neighbors.
• H - Lists the neighbors in order they were learned.
• Address - IPv6 link-local address of the neighbor.
• Interface - Local interface that received the Hello.
• Hold - Current hold time.
• Uptime - Time since this neighbor was added.
• SRTT and RTO - Used by RTP.
• Queue Count - Should always be zero.
• Sequence Number - Used to track updates,
queries, and reply packets.

 The show ipv6 protocols command displays
the parameters and other information about
the state of any active IPv6 routing protocol
processes currently configured on the router.
1. EIGRP for IPv6 is an active dynamic routing
protocol on R1.
2. These are the k values used to calculate the
EIGRP composite metric.
3. The EIGRP for IPv6 router ID of R1 is 1.0.0.0.
4. Same as EIGRP for IPv4, EIGRP for IPv6
administrative distances have internal AD of
90 and external of 170 (default values).
5. The interfaces enabled for EIGRP for IPv6.

 Use the show ipv6 route command to examine the IPv6 routing table.
• EIGRP for IPv6 routes are denoted with a D.
 The figure shows that R1 has installed three EIGRP routes to remote
IPv6 networks in its IPv6 routing table:
• 2001:DB8:CAFE:2::/64 via R3 (FE80::3) using its Serial 0/0/1 interface
• 2001:DB8:CAFE:3::/64 via R3 (FE80::3) using its Serial 0/0/1 interface
• 2001:DB8:CAFE:A002::/64 via R3 (FE80::3) using its Serial 0/0/1 interface

6.5 Chapter Summary

Conclusion
Packet Tracer - Skills Integration Challenge

 EIGRP (Enhanced Interior Gateway Routing Protocol) is a classless, distance vector routing
protocol.
 EIGRP uses the source code of "D" for DUAL in the routing table. EIGRP has a default
administrative distance of 90 for internal routes and 170 for routes imported from an external source,
such as default routes. These features include: Diffusing Update Algorithm (DUAL), establishing
neighbor adjacencies, Reliable Transport Protocol (RTP), partial and bounded updates, and equal
and unequal cost load balancing.
 EIGRP uses PDMs (Protocol Dependent Modules) giving it the capability to support different Layer
3 protocols including IPv4 and IPv6. EIGRP uses reliable delivery for EIGRP updates, queries and
replies; and uses unreliable delivery for EIGRP Hellos and acknowledgments. Reliable RTP means
an EIGRP acknowledgment must be returned.
 Before any EIGRP updates are sent, a router must first discover its neighbors using EIGRP Hello
packets. The Hello and hold-down values do not need to match for two routers to become
neighbors. The show ip eigrp neighbors command is used to view the neighbor table and verify
that EIGRP has established an adjacency with its neighbors.
Conclusion
Chapter 6: EIGRP

 EIGRP sends partial or bounded updates, which include only route changes. Updates are sent only
to those routers that are affected by the change. EIGRP composite metric uses bandwidth, delay,
reliability, and load to determine the best path. By default only bandwidth and delay are used.
 At the center of EIGRP is DUAL (Diffusing Update Algorithm). The DUAL Finite State Machine is
used to determine best path and potential backup paths to every destination network. The
successor is a neighboring router that is used to forward the packet using the least-cost route to the
destination network. Feasible distance (FD) is the lowest calculated metric to reach the destination
network through the successor. A feasible successor (FS) is a neighbor who has a loop-free backup
path to the same network as the successor, and also meets the feasibility condition. The feasibility
condition (FC) is met when a neighbor's reported distance (RD) to a network is less than the local
router's feasible distance to the same destination network. The reported distance is simply an
EIGRP neighbor's feasible distance to the destination network.
Conclusion
Chapter 6: EIGRP (Cont.)

 EIGRP is configured with the router eigrp autonomous-system command. The autonomous-
system value is actually a process-id and must be the same on all routers in the EIGRP routing
domain. The network command is similar to that used with RIP. The network is the classful network
address of the directly connected interfaces on the router. A wildcard mask is an optional parameter
that can be used to include only specific interfaces.
 EIGRP for IPv6 shares many similarities with EIGRP for IPv4. However, unlike the IPv4 network
command, IPv6 is enabled on the interface using the ipv6 eigrp autonomous-system interface
configuration command.
Conclusion
Chapter 6: EIGRP (Cont.)

New Terms and Commands
• named EIGRP
• Reliable Transport Protocol
• partial update
• bounded update
• equal cost load balancing
• unequal cost load balancing
• neighbor table
• topology table
• Update packet
• Acknowledgement packets
• Query and Reply packets
• non-broadcast multiple access
(NBMA)
• Hello interval
• type, length, value (TLV)
• Autonomous System Number
• composite metric
• Internet Assigned Numbers
Authority (IANA)
• regional Internet registry (RIR)
• loopback interface
• wildcard mask / inverse mask
• automatic summarization
• Successor
• Feasible Distance (FD)
• Feasible Successor (FS)
• Reported Distance (RD)
• Advertised Distance (AD)
• composite metric
• Internet Assigned Numbers
Authority (IANA)
• regional Internet registry (RIR)
• wildcard mask / inverse mask
• automatic summarization
• Successor
• Feasible Distance (FD)
• Feasible Successor (FS)
• Reported Distance (RD)
• Advertised Distance (AD)
• Feasible Condition (FC)
• Finite State Machine (FSM)
• passive state / active state

EIGRP

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