4-1 © 2001, Cisco Systems, Inc. Configuring EIGRP Module 4
4-1© 2001, Cisco Systems, Inc.
Configuring EIGRPConfiguring EIGRPModule 4Module 4
EIGRP OverviewEIGRP Overview
© 2001, Cisco Systems, Inc. 4-2
BSCI v1.2—4-3© 2001, Cisco Systems, Inc.
EIGRP supports:• Rapid convergence
• Reduced bandwidth usage
• Multiple network-layer protocols
What Is EIGRP?What Is EIGRP?
EnhancedIGRP
IPX RoutingProtocols
AppleTalk Routing Protocol
IP RoutingProtocols
IPX RoutingProtocols
AppleTalk Routing Protocol
IP RoutingProtocols
BSCI v1.2—4-4© 2001, Cisco Systems, Inc.
EIGRP FeaturesEIGRP Features
• Advanced distance vector
• 100% loop free
• Fast convergence
• Easy configuration
• Less network design constraints than OSPF
BSCI v1.2—4-5© 2001, Cisco Systems, Inc.
EIGRP Features (cont.)EIGRP Features (cont.)
• Incremental updates
• Supports VLSM and discontiguous networks
• Classless routing
• Compatible with existing IGRP networks
• Protocol independent (supports IPX and AppleTalk)
BSCI v1.2—4-6© 2001, Cisco Systems, Inc.
Advantages of EIGRPAdvantages of EIGRP
• Multicast instead of broadcast
• Use of link bandwidth and delay
–EIGRP metric = IGRP metric x 256(32 bit versus 24 bit)
• Unequal cost path load balancing
BSCI v1.2—4-7© 2001, Cisco Systems, Inc.
EIGRP Support for IP AddressesEIGRP Support for IP Addresses
EIGRP supports:• VLSMs
• Hierarchical designs
/16
D
/27
/30
/24
World
NM
A
PO
B
SR
C
BSCI v1.2—4-8© 2001, Cisco Systems, Inc.
EIGRP TerminologyEIGRP Terminology
Neighbor Table—AppleTalkDestination Next Hop Router
Neighbor Table—IPXDestination Next Hop Router
Neighbor Table—IPNext-Hop Interface Router
BSCI v1.2—4-9© 2001, Cisco Systems, Inc.
EIGRP Terminology (cont.)EIGRP Terminology (cont.)
Neighbor Table—AppleTalkDestination Next Hop Router
Neighbor Table—IPXDestination Next Hop Router
Neighbor Table—IPNext-Hop Interface Router
Topology Table—AppleTalkDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPXDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPDestination 1
BSCI v1.2—4-10© 2001, Cisco Systems, Inc.
EIGRP Terminology (cont.)EIGRP Terminology (cont.)
Topology Table—AppleTalkDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPXDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPDestination 1
Routing Table—AppleTalkDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPXDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPDestination 1
Neighbor Table—AppleTalkDestination Next Hop Router
Neighbor Table—IPXDestination Next Hop Router
Neighbor Table—IPNext-Hop Interface Router
BSCI v1.2—4-11© 2001, Cisco Systems, Inc.
EIGRP Terminology (cont.)EIGRP Terminology (cont.)
Topology Table—AppleTalkDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPXDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPDestination 1 Successor
Routing Table—AppleTalkDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPXDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPDestination 1 Successor
Neighbor Table—AppleTalkDestination Next Hop Router
Neighbor Table—IPXDestination Next Hop Router
Neighbor Table—IPNext-Hop Interface Router
BSCI v1.2—4-12© 2001, Cisco Systems, Inc.
EIGRP Terminology (cont.)EIGRP Terminology (cont.)
Topology Table—AppleTalkDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPXDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost
Topology Table—IPDestination 1 SuccessorDestination 1 Feasible Successor
Routing Table—AppleTalkDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPXDestination 1 Next Router XDestination 1 Next Router X
Routing Table—IPDestination 1 Successor
Neighbor Table—AppleTalkDestination Next Hop Router
Neighbor Table—IPXDestination Next Hop Router
Neighbor Table—IPNext-Hop Interface Router
EIGRP OperationEIGRP Operation
© 2001, Cisco Systems, Inc. 4-13
BSCI v1.2—4-14© 2001, Cisco Systems, Inc.
EIGRP PacketsEIGRP Packets
• Hello: Establish neighbor relationships
• Update: Send routing updates
• Query: Ask neighbors aboutrouting information
• Reply: Response to query aboutrouting information
• ACK: Acknowledgment of a reliable packet
BSCI v1.2—4-15© 2001, Cisco Systems, Inc.
What Is in a Neighbor Table?What Is in a Neighbor Table?
p2r2
p2r2#show ip eigrp neighborsIP-EIGRP neighbors for process 400H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num1 172.68.2.2 To0 13 02:15:30 8 200 0 90 172.68.16.2 Se1 10 02:38:29 29 200 0 6
BSCI v1.2—4-16© 2001, Cisco Systems, Inc.
EIGRP ReliabilityEIGRP Reliability
• EIGRP reliable packets are packets that require explicit acknowledgment:
–Update
–Query
–Reply
• EIGRP unreliable packets are packets that do not require explicit acknowledgment:
–Hello
–ACK
BSCI v1.2—4-17© 2001, Cisco Systems, Inc.
I am router A, who is on the link?Hello
A B
1
Initial Route DiscoveryInitial Route Discovery
BSCI v1.2—4-18© 2001, Cisco Systems, Inc.
Here is my complete routing information. Update2
Initial Route Discovery (cont.)Initial Route Discovery (cont.)
I am router A, who is on the link?Hello
A B
1
BSCI v1.2—4-19© 2001, Cisco Systems, Inc.
Thanks for the information!Ack3
Initial Route Discovery (cont.)Initial Route Discovery (cont.)
Here is my complete routing information. Update2
I am router A, who is on the link?Hello
A B
1
BSCI v1.2—4-20© 2001, Cisco Systems, Inc.
Topology Table
34
Initial Route Discovery (cont.)Initial Route Discovery (cont.)
Thanks for the information!Ack3
Here is my complete routing information. Update2
I am router A, who is on the link?Hello
A B
1
BSCI v1.2—4-21© 2001, Cisco Systems, Inc.
34
Thanks for the information!Ack3
Here is my complete routing information. Update2
I am router A, who is on the link?Hello
A B
1
Initial Route Discovery (cont.)Initial Route Discovery (cont.)
Here is my complete route information.Update
Topology Table
5
BSCI v1.2—4-22© 2001, Cisco Systems, Inc.
Initial Route Discovery (cont.)Initial Route Discovery (cont.)
Converged
Thanks for the information! Ack 6
34
Thanks for the information!Ack3
Here is my complete routing information. Update2
I am router A, who is on the link?Hello
B
1
Here is my complete route information.Update5
Topology Table
A
BSCI v1.2—4-23© 2001, Cisco Systems, Inc.
EIGRP uses a composite metric to pick the best path
EIGRP Route SelectionEIGRP Route Selection
IPX
19.2
T1
T1 T1
IPX
AppleTalk
IP
AppleTalk
IP
A B
DC
BSCI v1.2—4-24© 2001, Cisco Systems, Inc.
EIGRP Metrics CalculationEIGRP Metrics Calculation
• Metric = [K1 x BW + (K2 x BW) / (256 – load) + K3 x delay] x [K5 / (reliability + K4)]
–By default: K1 = 1, K2 = 0, K3 = 1, K4 = 0, K5 = 0
• Delay is sum of all the delays of the links along the paths
–Delay = [Delay in 10s of microseconds] x 256
• BW = the lowest bandwidth of the links along the paths
–BW = [10000000 / (bandwidth in Kbps)] x 256
• By default, metric = BW + delay
BSCI v1.2—4-25© 2001, Cisco Systems, Inc.
EIGRP DUALEIGRP DUAL
• Diffusing Update Algorithm (DUAL)
• Finite-state machine
– Tracks all routes advertised by neighbors
–Selects loop-free path using a successor and remembers any feasible successors
– If successor lost:
• Use feasible successor
– If no feasible successor:
• Query neighbors and recompute new successor
BSCI v1.2—4-26© 2001, Cisco Systems, Inc.
DUAL Example (Start) DUAL Example (Start)
E EIGRP FD AD Topology (a) 3 (fd)
via D 3 2 (Successor)via C 4 3
D EIGRP FD AD Topology(a) 2 (fd)
via B 2 1 (Successor)via C 5 3
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via D 4 2 (fs)via E 4 3
(1)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
BSCI v1.2—4-27© 2001, Cisco Systems, Inc.
DUAL ExampleDUAL Example
(1)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 3 (fd)
via D 3 2 (Successor)via C 4 3
D EIGRP FD AD Topology(a) 2 (fd)
via B 2 1 (Successor)via C 5 3
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via D 4 2 (fs)via E 4 3
XXXX
BSCI v1.2—4-28© 2001, Cisco Systems, Inc.
DUAL Example (cont.)DUAL Example (cont.)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 3 (fd)
via D 3 2 (Successor)via C 4 3
D EIGRP FD AD Topology(a) **ACTIVE** -1 (fd)
via E (q)via C 5 3 (q)
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via Dvia E 4 3
BSCI v1.2—4-29© 2001, Cisco Systems, Inc.
DUAL Example (cont.)DUAL Example (cont.)
RR
Q
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) **ACTIVE** -1 (fd)
via D via C 4 3 (q)
D EIGRP FD AD Topology(a) **ACTIVE** -1 (fd)
via E (q)via C 5 3
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via D via E
BSCI v1.2—4-30© 2001, Cisco Systems, Inc.
DUAL Example (cont.)DUAL Example (cont.)
RR
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 4 (fd)
via C 4 3 (Successor)via D
D EIGRP FD AD Topology(a) **ACTIVE** -1 (fd)
via E (q)via C 5 3
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via Dvia E
BSCI v1.2—4-31© 2001, Cisco Systems, Inc.
DUAL Example (cont.)DUAL Example (cont.)
RR
(1)
(1)
(1)
(2)(2)
(a)
A
E
B
E EIGRP FD AD Topology (a) 4 (fd)
via C 4 3 (Successor)via D
D EIGRP FD AD Topology(a) 5 (fd)
via C 5 3 (Successor)via E 5 4 (Successor)
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via Dvia E
D
C
BSCI v1.2—4-32© 2001, Cisco Systems, Inc.
DUAL Example (cont.)DUAL Example (cont.)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 4 (fd)
via C 4 3 (Successor)via D
D EIGRP FD AD Topology(a) 5 (fd)
via C 5 3 (Successor)via E 5 4 (Successor)
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via Dvia E
BSCI v1.2—4-33© 2001, Cisco Systems, Inc.
DUAL Example (Start) DUAL Example (Start)
(1)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 3 (fd)
via D 3 2 (Successor)via C 4 3
D EIGRP FD AD Topology(a) 2 (fd)
via B 2 1 (Successor)via C 5 3
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via D 4 2 (fs)via E 4 3
BSCI v1.2—4-34© 2001, Cisco Systems, Inc.
DUAL Example (End)DUAL Example (End)
(1)
(1)
(1)
(2)(2)
(a)
A
E
D
C
B
E EIGRP FD AD Topology (a) 4 (fd)
via C 4 3 (Successor)via D
D EIGRP FD AD Topology(a) 5 (fd)
via C 5 3 (Successor)via E 5 4 (Successor)
C EIGRP FD AD Topology(a) 3 (fd)
via B 3 1 (Successor)via Dvia E
Configuring EIGRP Configuring EIGRP
© 2001, Cisco Systems, Inc. 4-35
BSCI v1.2—4-36© 2001, Cisco Systems, Inc.
EIGRP Load BalancingEIGRP Load Balancing
• Routes with metric equal to the minimum metric will be installed in the routing table (equal-cost load balancing)
• Up to six entries in the routing table for the same destination
– Number of entries is configurable
– Default is four
BSCI v1.2—4-37© 2001, Cisco Systems, Inc.
10
20
10
10
20
25variance 2
Variance ExampleVariance Example
• Router E will choose Router C to get to Network Z because FD = 20
• With variance of 2, Router E will also choose Router B to get to Network Z (20 + 10) < (2 x [FD])
• Router D will not be used to get to Network Z (45 > 40)
Network Z
(config-router)#AE
D
C
B
Verifying EIGRP Operation
Verifying EIGRP Operation
© 2001, Cisco Systems, Inc. 4-38
BSCI v1.2—4-39© 2001, Cisco Systems, Inc.
Verifying EIGRP OperationVerifying EIGRP Operation
show ip protocols
Router#
show ip route eigrp
Router#
show ip eigrp traffic
Router#
show ip eigrp neighbors
Router#
show ip eigrp topology
Router#
• Displays the neighbors discovered by IP EIGRP
• Displays the IP EIGRP topology table
• Displays current EIGRP entries in the routing table
• Displays the parameters and current state of the active routing protocol process
• Displays the number of IP EIGRP packets sent and received
BSCI v1.2—4-40© 2001, Cisco Systems, Inc.
Verifying EIGRP Operation (cont.)Verifying EIGRP Operation (cont.)
debug ip eigrp summary
Router#
debug ip eigrp
Router#
debug eigrp packets
Router#
debug eigrp neighbors
Router#
• Displays all types of EIGRP packets, both sent and received
• Displays the EIGRP neighbor interaction
• Displays advertisements and changes EIGRP makes to the routing table
• Displays a brief report of the EIGRP routing activity