© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-1 Implementing an EIGRP-Based Solution Implementing and Verifying Basic EIGRP for the Enterprise

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-1

Implementing an EIGRP-Based Solution

Implementing and Verifying Basic EIGRP for the Enterprise LAN Architecture


EIGRP Deployment

interface FastEthernet0/0 ip address 172.16.1.1 255.255.255.0 !interface Serial0/0/1 bandwidth 512 ip address 192.168.1.101 255.255.255.224!router eigrp 110 network 172.16.1.0 0.0.0.255 network 192.168.1.0

interface FastEthernet0/0 ip address 172.17.2.2 255.255.255.0 !interface Serial0/0/1 bandwidth 512 ip address 192.168.1.102 255.255.255.224!router eigrp 110 network 172.17.2.0 0.0.0.255 network 192.168.1.0

R1# R2#


Verifying EIGRP Neighbors

R1#show ip eigrp neighborsIP-EIGRP neighbors for process 110H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 5

R2#show ip eigrp neighborsIP-EIGRP neighbors for process 110H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num0 192.168.1.101 Se0/0/1 10 00:17:02 10 1380 0 5


Verifying EIGRP Neighbors (Cont.)

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

R1#show ip eigrp neighborsIP-EIGRP neighbors for process 110H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 51 2 3 4 5 6 7 8 9


Verifying EIGRP Neighbors (Cont.)

R1#show ip eigrp neighbors detailIP-EIGRP neighbors for process 110H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num0 192.168.1.102 Se0/0/1 14 00:17:55 0 4500 3 274 Last startup serial 569 Version 12.4/1.0, Retrans: 2, Retries: 2, Waiting for Init Ack UPDATE seq 307 ser 29-569 Sent 8924 Init Sequenced UPDATE seq 310 ser 570-573 Sequenced UPDATE seq 312 ser 574-578 Sequenced

Current retry count

Neighbor version of Cisco IOS

Current pending packets

Total retransmission count


Verifying EIGRP Routes

R1#show ip route eigrpD 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:07:01, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masksD 172.16.0.0/16 is a summary, 00:05:13, Null0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masksD 192.168.1.0/24 is a summary, 00:05:13, Null0

EIGRP route type

Network

Next hop Route ageAD / Metric


R1#show ip protocolsRouting 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: 172.16.1.0/24 192.168.1.0 Routing Information Sources: Gateway Distance Last Update (this router) 90 00:09:38 Gateway Distance Last Update 192.168.1.102 90 00:09:40 Distance: internal 90 external 170

Verifying EIGRP Operation

K values

Load-balancing setting

Networks being announced

EIGRP local AD


Verifying EIGRP Operation (Cont.)

Peer count

R1#show ip eigrp topologyIP-EIGRP Topology Table for AS(110)/ID(192.168.1.101)Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia StatusP 192.168.1.96/27, 1 successors, FD is 40512000 via Connected, Serial0/0/1P 192.168.1.0/24, 1 successors, FD is 40512000 via Summary (40512000/0), Null0P 172.16.0.0/16, 1 successors, FD is 28160 via Summary (28160/0), Null0P 172.16.1.0/24, 1 successors, FD is 28160 via Connected, FastEthernet0/0P 172.17.0.0/16, 1 successors, FD is 40514560 via 192.168.1.102 (40514560/28160), Serial0/0/1

Route status

Feasible distance

Advertiseddistance

Next hop

Outgoing interface

R1#show ip eigrp interfacesIP-EIGRP interfaces for process 110 Xmit Queue Mean Pacing Time Multicast PendingInterface Peers Un/Reliable SRTT Un/Reliable Flow Timer RoutesFa0/0 0 0/0 0 0/10 0 0Se0/0/1 1 0/0 10 10/380 424 0


R1#show ip eigrp trafficIP-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

Verifying EIGRP Operation (Cont.)

EIGRP packet counters


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

Using Passive Interfaces

R1# R2#

router eigrp 110 passive-interface FastEthernet0/0 network 172.16.1.0 0.0.0.255 network 192.168.1.0

router eigrp 110 passive-interface FastEthernet0/0 network 172.17.2.0 0.0.0.255 network 192.168.1.0

No peer hereNo peer here


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 172.16.1.0 0.0.0.255 network 192.168.1.0


Verify Operation with Passive Interfaces


Using the ip default network Command with EIGRP

Default routes decrease the size of the routing table

Multiple candidates:

– 0.0.0.0 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


Flagging an external network as a default route candidate

Using the ip default network Command with EIGRP (Cont.)

router eigrp 110 network 10.0.0.0ip default-network 172.31.0.0ip route 172.31.0.0 255.255.0.0 172.31.1.1

R2#


Verifying Default Network Information

Flagged candidate

Flagged candidate

R1#show ip route<output omitted>Gateway of last resort is 10.64.0.2 to network 0.0.0.0 10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks<output omitted>C 10.64.0.0/24 is directly connected, FastEthernet0/0D* 172.31.0.0/16 [90/10514560] via 10.64.0.2, 00:07:01, FastEthernet0/0

R2#show ip route

0.0.0.0 via Serial0/0/0<output omitted>S* 0.0.0.0/0 [1/0] via 172.31.1.1C 172.31.1.0/24 is directly connected, Serial0/0/0C 10.64.0.0/24 is directly connected, FastEthernet0/0


Route Summarization

Improves network scalability

– Smaller routing tables

– Fewer updates

Should follow IP addressing


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


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.

EIGRP Manual Route Summarization


router eigrp 110 network 10.0.0.0 network 172.16.0.0 no auto-summary

R1(config)#

router eigrp 110 network 10.0.0.0 network 172.16.0.0 no auto-summary

R2(config)#

Configuring Route Summarization

Creating a summary route for 172.16.0.0/16

interface Serial0/0/0 ip address 192.168.4.2 255.255.255.0 ip summary-address eigrp 110 172.16.0.0 255.255.0.0!router eigrp 110 network 10.0.0.0 network 192.168.4.0 no auto-summary

R3(config)#


Verifying Route Summarization

R3#show ip route<output omitted> Gateway of last resort is not set 172.16.0.0/16 is variably subnetted, 3 subnets, 2 masksD 172.16.0.0/16 is a summary, 00:00:04, Null0D 172.16.1.0/24 [90/156160] via 10.1.1.2, 00:00:04, FastEthernet0/0D 172.16.2.0/24 [90/20640000] via 10.2.2.2, 00:00:04, Serial0/0/1C 192.168.4.0/24 is directly connected, Serial0/0/0 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masksC 10.2.2.0/24 is directly connected, Serial0/0/1<output omitted>


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.


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.


Documents

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—2-1 Implementing an EIGRP-Based Solution Implementing and Verifying Basic EIGRP for the Enterprise