1. Implementing an EIGRP-Based Solution
Implementing and Verifying Basic EIGRP for the Enterprise LAN Architecture
Implementing an EIGRP-Based Solution

2. EIGRP Deployment R1# R2# interface FastEthernet0/0
ip address !
interface Serial0/0/1
bandwidth 512
ip address
router eigrp 110
network
network
interface FastEthernet0/0
ip address !
interface Serial0/0/1
bandwidth 512
ip address
router eigrp 110
network
network

3. Verifying EIGRP Neighbors
R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 110
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
Se0/0/ :07:
R2#show ip eigrp neighbors
IP-EIGRP neighbors for process 110
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
Se0/0/ :17:

4. Verifying EIGRP Neighbors (Cont.)
R1#show ip eigrp neighbors
IP-EIGRP neighbors for process 110
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
Se0/0/ :07: 1 2 3 4 5 6 7 8 9 1.
Neighbor index 2.
Neighbor IP address 3.
Interface on which the neighbor is reachable 4.
Remaining hold time 5.
Neighbor uptime 6.
Smooth round-trip time 7.
Retransmission timeout 8.
Number of packets to send to neighbor 9.
Last sequence received

5. Verifying EIGRP Neighbors (Cont.)
Total retransmission count
Current retry count
R1#show ip eigrp neighbors detail
IP-EIGRP neighbors for process 110
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
Se0/0/ :17:
Last startup serial 569
Version 12.4/1.0, Retrans: 2, Retries: 2, Waiting for Init Ack
UPDATE seq 307 ser Sent 8924 Init Sequenced
UPDATE seq 310 ser Sequenced
UPDATE seq 312 ser Sequenced
Neighbor version of Cisco IOS
Current pending packets

6. Verifying EIGRP Routes
Network
EIGRP route type
Next hop
Route age
AD / Metric
R1#show ip route eigrp
D /16 [90/ ] via , 00:07:01, Serial0/0/1
/16 is variably subnetted, 2 subnets, 2 masks
D /16 is a summary, 00:05:13, Null0
/24 is variably subnetted, 2 subnets, 2 masks
D /24 is a summary, 00:05:13, Null0

7. Verifying EIGRP Operation
R1#show ip protocols
Routing Protocol is "eigrp 110"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
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 110
EIGRP NSF-aware route hold timer is 240s
<output omitted>
Maximum path: 4
Routing for Networks:
/24
Routing Information Sources:
Gateway Distance Last Update
(this router) :09:38
:09:40
Distance: internal 90 external 170
K values
Load-balancing setting
Networks being announced
EIGRP local AD

8. Verifying EIGRP Operation (Cont.)
R1#show ip eigrp interfaces
IP-EIGRP interfaces for process 110
Xmit Queue Mean Pacing Time Multicast Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes
Fa0/ / /
Se0/0/ / /
Peer count
R1#show ip eigrp topology
IP-EIGRP Topology Table for AS(110)/ID( )
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P /27, 1 successors, FD is
via Connected, Serial0/0/1
P /24, 1 successors, FD is
via Summary ( /0), Null0
P /16, 1 successors, FD is 28160
via Summary (28160/0), Null0
P /24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P /16, 1 successors, FD is
via ( /28160), Serial0/0/1
Route status
Feasible
distance
Advertised
distance
Outgoing
interface
Next hop

9. Verifying EIGRP Operation (Cont.)
R1#show ip eigrp traffic
IP-EIGRP Traffic Statistics for AS 110
Hellos sent/received: 429/192
Updates sent/received: 4/4
Queries sent/received: 1/0
Replies sent/received: 0/1
Acks sent/received: 4/3
Input queue high water mark 1, 0 drops
SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
Hello Process ID: 113
PDM Process ID: 73
EIGRP packet counters

10. Using Passive Interfaces
EIGRP announces the directly connected network of an interface
EIGRP does not try to form neighbor relationships over the interface where only the host is connected
Reduces traffic overhead
No peer here
No peer here
R1#
R2#
router eigrp 110
passive-interface FastEthernet0/0
network
network
router eigrp 110
passive-interface FastEthernet0/0
network
network

11. Using Passive Interfaces (Cont.)
No need to talk to host by EIGRP
Disables EIGRP on all interfaces by default
Enables EIGRP only on selected interfaces
R1(config)#
router eigrp 110
passive-interface default
no passive-interface Serial0/0/1
network
network

12. Verify Operation with Passive Interfaces
R1#sh ip protocols
Routing Protocol is "eigrp 110"
<output omitted>
Automatic network summarization is in effect
Automatic address summarization:
/16 for Serial0/0/1
Summarizing with metric 28160
Maximum path: 4
Routing for Networks:
/24
Passive Interface(s):
FastEthernet0/0

13. Using the ip default network Command with EIGRP
Default routes decrease the size of the routing table
Multiple candidates:
is statically set or advertised by the routing protocol
Any EIGRP major network route is flagged as a candidate default with the ip default-network command
EIGRP solution:
Flags network as a default route candidate
Multiple default candidates supported
Announced with the Exterior flag

14. Using the ip default network Command with EIGRP (Cont.)
Flagging an external network as a default route candidate
R2#
router eigrp 110
network
ip default-network
ip route

15. Verifying Default Network Information
R2#show ip route
via Serial0/0/0
<output omitted>
S* /0 [1/0] via
C /24 is directly connected, Serial0/0/0
C /24 is directly connected, FastEthernet0/0
Flagged candidate
Flagged candidate
R1#show ip route
<output omitted>
Gateway of last resort is to network
/8 is variably subnetted, 7 subnets, 2 masks
C /24 is directly connected, FastEthernet0/0
D* /16 [90/ ] via , 00:07:01, FastEthernet0/0

16. Route Summarization Improves network scalability
Smaller routing tables
Fewer updates
Should follow IP addressing

17. EIGRP Automatic Route Summarization
Performed on major network boundaries
Subnetworks are summarized to a single classful (major) network.
Automatic summarization occurs by default.
Could result in routing issues—disable auto summarization

18. EIGRP Manual Route Summarization
Configurable on a per-interface basis in any router within a network.
Summarization results in a route pointing to null0.
Loop prevention mechanism
When the last specific route of the summary goes away, the summary is deleted.
The minimum metric of the specific routes = metric of the summary route.

19. Configuring Route Summarization
Creating a summary route for /16
router eigrp 110
network
network
no auto-summary
R1(config)#
interface Serial0/0/0
ip address
ip summary-address eigrp !
router eigrp 110
network
network
no auto-summary
R3(config)#
router eigrp 110
network
network
no auto-summary
R2(config)#

20. Verifying Route Summarization
R3#show ip route
<output omitted>
Gateway of last resort is not set
/16 is variably subnetted, 3 subnets, 2 masks
D /16 is a summary, 00:00:04, Null0
D /24 [90/156160] via , 00:00:04, FastEthernet0/0
D /24 [90/ ] via , 00:00:04, Serial0/0/1
C /24 is directly connected, Serial0/0/0
/8 is variably subnetted, 3 subnets, 2 masks
C /24 is directly connected, Serial0/0/1

21. Summary
EIGRP operation can be verified by examining the EIGRP neighbor relationship information and IP routing table for the presence of EIGRP routes.
The neighbor command can be used to form the EIGRP neighbor relationship with only specific neighbors using unicast packets.
EIGRP is, by default, enabled on all interfaces included with the network command. To prevent unnecessary traffic, interfaces without neighbors should be made passive.

22. Summary (Cont.)
Create and advertise a default route in an EIGRP autonomous system with the ip default-network network-number command.
EIGRP performs automatic network-boundary summarization, but administrators can disable automatic summarization and perform manual route summarization on an interface-by-interface basis. Summarizing routes results in smaller routing tables.
For manual route summarization, the summary route is advertised only if a more specific entry of the summary route is present in the routing table.