Implementing Basic EIGRP

2 Basic Configuration

2.1 Configuration basics

figure 1

Objectives

• Configure EIGRP for the shown network using EIGRP AS 90. Corporate policy dictates you must
use specific wildcard mask on R2 and R3. In addition, EIGRP should be configured in such a way that
it does not operate like a classful routing protocol. Finally, the BB router has a static route to
192.168.1.0/24; R2 and R3 should receive this route via EIGRP without using redistribution

configuration for BB

interface Loopback0
ip address 172.30.0.1 255.255.255.0
!
interface Loopback1
ip address 172.30.1.1 255.255.255.0
!
interface Loopback2
ip address 172.30.2.1 255.255.255.0
!
interface Loopback3
ip address 172.30.3.1 255.255.255.0
!
interface Loopback4
ip address 172.30.4.1 255.255.255.0
!
interface Loopback5
ip address 172.30.5.1 255.255.255.0
!
interface Loopback6
ip address 172.30.6.1 255.255.255.0
!
interface Loopback7
ip address 172.30.7.1 255.255.255.0
!
interface Loopback8
ip address 172.30.8.1 255.255.255.0
!
.
.
!
interface Serial2/0
bandwidth 128
ip address 10.1.24.1 255.255.255.252
serial restart-delay 0
!
interface Serial2/1
bandwidth 256
ip address 10.1.34.1 255.255.255.252
serial restart-delay 0
!
.
.

router eigrp 90
network 10.1.0.0 0.0.255.255
network 172.30.0.0
no auto-summary
.
.
ip route 192.168.1.0 255.255.255.0 Null0

configuration for R2#

!
interface FastEthernet0/0
ip address 10.1.2.2 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.1.25.2 255.255.255.0
duplex auto
speed auto
!
interface Serial2/0
bandwidth 128
ip address 10.1.24.2 255.255.255.252
serial restart-delay 0
!
.
.
router eigrp 90
network 10.1.2.2 0.0.0.0
network 10.1.24.2 0.0.0.0
network 10.1.25.2 0.0.0.0
no auto-summary

configuration for R3#
!
interface FastEthernet0/0
ip address 10.1.2.3 255.255.255.0
duplex auto
speed auto
!
.
.
!
interface Serial2/1
bandwidth 256
ip address 10.1.34.2 255.255.255.252
serial restart-delay 0
!
.
.
!
router eigrp 90
network 10.1.2.3 0.0.0.0
network 10.1.34.2 0.0.0.0
no auto-summary
!




redistribute static

BB(config-router)#redistribute static
On R2# with the show command you see an EIGRP external route
D EX 192.168.1.0/24 [170/10514432] via 10.1.2.3, 00:00:41, FastEthernet0/0

BB(config-router)#network 192.168.1.0
You can also choose the network comman in the EIGRP process to insert the static route. It’s very simple and you get following output on R2#
D 192.168.1.0/24 [90/10514432] via 10.1.2.3, 00:02:13, FastEthernet0/0


• R2 and R3 should have a default route pointing to the 192.168.1.0/24 network at the corporate
office. No static routes can be used to accomplish this.

* – candidate default

BB#conf t
BB(config)#ip default-network 192.168.1.0
.
.
BB(config)#do show ip route
Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route

Gateway of last resort is not set

172.30.0.0/24 is subnetted, 9 subnets
C 172.30.2.0 is directly connected, Loopback2
C 172.30.3.0 is directly connected, Loopback3
C 172.30.0.0 is directly connected, Loopback0
C 172.30.1.0 is directly connected, Loopback1
C 172.30.6.0 is directly connected, Loopback6
C 172.30.7.0 is directly connected, Loopback7
C 172.30.4.0 is directly connected, Loopback4
C 172.30.5.0 is directly connected, Loopback5
C 172.30.8.0 is directly connected, Loopback8
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D 10.1.2.0/24 [90/10514432] via 10.1.34.2, 00:02:40, Serial2/1
D 10.1.25.0/24 [90/10516992] via 10.1.34.2, 00:02:40, Serial2/1
C 10.1.24.0/30 is directly connected, Serial2/0
C 10.1.34.0/30 is directly connected, Serial2/1
S* 192.168.1.0/24 is directly connected, Null0
.
.
R2#show ip route
Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route

Gateway of last resort is 10.1.2.3 to network 192.168.1.0

172.30.0.0/24 is subnetted, 9 subnets
D 172.30.2.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.3.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.0.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.1.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.6.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.7.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.4.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.5.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D 172.30.8.0 [90/10642432] via 10.1.2.3, 00:34:58, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 10.1.2.0/24 is directly connected, FastEthernet0/0
C 10.1.25.0/24 is directly connected, FastEthernet0/1
C 10.1.24.0/30 is directly connected, Serial2/0
D 10.1.34.0/30 [90/10514432] via 10.1.2.3, 00:34:58, FastEthernet0/0
D* 192.168.1.0/24 [90/10514432] via 10.1.2.3, 00:03:22, FastEthernet0/0

the network command has to be classful
It is a valid method to send a default route in EIGRP

• In order to meet security standards, EIGRP should not form neighbor relationships on any interface
where other EIGRP routers do not exist.

we need a passive interface

R2#sh ip int brie
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.1.2.2 YES NVRAM up up
FastEthernet0/1 10.1.25.2 YES NVRAM up up
FastEthernet1/0 unassigned YES NVRAM administratively down down
FastEthernet1/1 unassigned YES NVRAM administratively down down
Serial2/0 10.1.24.2 YES NVRAM up up
Serial2/1 unassigned YES NVRAM administratively down down
Serial2/2 unassigned YES NVRAM administratively down down

R2#conf t
R2(config)#router eig 90
R2(config-router)#pass
R2(config-router)#passive-interface fa0/1
R2(config-router)#

in EIGRP no hellos were send on dedicated interfaces, but for example RIP advertisements can be received.

Same thing on Router BB#

BB#sh run | s eigr
router eigrp 90
passive-interface default
no passive-interface Serial2/0
no passive-interface Serial2/1
network 10.1.0.0 0.0.255.255
network 172.30.0.0
network 192.168.1.0
no auto-summary

BB#



• To improve the efficiency of the remote routers R2 and R3, the corporate BB router should
summarize 172.30.0.0 – 172.30.7.255 into a single network advertisement.

on BB# we need interface s2/0 and s2/1 to do so

BB(config)#int s2/0
BB(config-if)#ip summary-address eigrp 90 172.30.0.0 255.255.248.0
.
.
R2#sh ip route
Codes: C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route

Gateway of last resort is 10.1.2.3 to network 192.168.1.0

172.30.0.0/16 is variably subnetted, 10 subnets, 2 masks
D 172.30.2.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.3.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.0.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.0.0/21 [90/20640000] via 10.1.24.1, 00:02:10, Serial2/0
D 172.30.1.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.6.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.7.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.4.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.5.0/24 [90/10642432] via 10.1.2.3, 00:02:11, FastEthernet0/0
D 172.30.8.0/24 [90/10642432] via 10.1.2.3, 00:10:30, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 10.1.2.0/24 is directly connected, FastEthernet0/0
C 10.1.25.0/24 is directly connected, FastEthernet0/1
C 10.1.24.0/30 is directly connected, Serial2/0
D 10.1.34.0/30 [90/10514432] via 10.1.2.3, 00:10:32, FastEthernet0/0
D* 192.168.1.0/24 [90/10514432] via 10.1.2.3, 00:10:30, FastEthernet0/0
R2#
BB(config-if)#

nothing happens because successor point to router R3#. We need both serial interfaces to do this summarization.

BB(config-if)#int s2/1
BB(config-if)#ip summary-address eigrp 90 172.30.0.0 255.255.248.0
BB(config-if)#
*Aug 16 09:39:26.815: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 90: Neighbor 10.1.34.2 (Serial2/1) is resync: summary configured
.
.
R2#sh ip route
.
.
172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
D 172.30.0.0/21 [90/10642432] via 10.1.2.3, 00:00:07, FastEthernet0/0
D 172.30.8.0/24 [90/10642432] via 10.1.2.3, 00:13:05, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 10.1.2.0/24 is directly connected, FastEthernet0/0
C 10.1.25.0/24 is directly connected, FastEthernet0/1
C 10.1.24.0/30 is directly connected, Serial2/0
D 10.1.34.0/30 [90/10514432] via 10.1.2.3, 00:13:08, FastEthernet0/0
D* 192.168.1.0/24 [90/10514432] via 10.1.2.3, 00:13:05, FastEthernet0/0
R2#
BB(config-if)#



• To best utilize available network bandwidth, the corporate BB router should perform unequal load
balancing to reach the 10.1.2.0/24 network.

unequal loadbalance

BB#sh ip eigrp topology
IP-EIGRP Topology Table for AS(90)/ID(172.30.8.1)

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.2.0/24, 1 successors, FD is 10514432
via 10.1.34.2 (10514432/28160), Serial2/1
via 10.1.24.2 (20514560/28160), Serial2/0
P 10.1.25.0/24, 1 successors, FD is 10516992
via 10.1.34.2 (10516992/30720), Serial2/1
via 10.1.24.2 (20514560/28160), Serial2/0


The successor has a Feasible distance of 10514432
The feasible successor has a feasible distance of 20514560
calculate = 10514432 * 2 = 21028864
The feasible successor is lower than the successor is two times. So it is a valid load balance value.

The show ip route command shows only one route to the network 10.1.2.0/24

10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D 10.1.2.0/24 [90/10514432] via 10.1.34.2, 00:00:08, Serial2/1
D 10.1.25.0/24 [90/10516992] via 10.1.34.2, 00:00:08, Serial2/1

BB#conf t
BB(config)#router eigrp 90
BB(config-router)#va
BB(config-router)#variance ?
<1-128> Metric variance multiplier
BB(config-router)#variance 2
BB(config-router)#end
BB#

After the variance command the output show 2 valid routes
.
.
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
D 10.1.2.0/24 [90/10514432] via 10.1.34.2, 00:00:03, Serial2/1
[90/20514560] via 10.1.24.2, 00:00:03, Serial2/0

• Now we finished all objectives