Today I will discuss about EIGRP unequal cost path load balancing. The following are the diagram describing the scenario. I have used five router for the setup. Router R1 having three path to connect router R5 loop back address. I have changed the interface bandwidth of router R1 interface F0/1 & F1/0 as 75000 & 50000. Kindly find the diagram & router configuration below.
R1
R1#sh run
Building configuration...
Current configuration : 1224 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
!
archive
log config
hidekeys
!
!
ip tcp synwait-time 5
ip ssh version 1
!
interface Loopback0
ip address 5.5.5.5 255.255.255.0
!
interface FastEthernet0/0
ip address 11.11.11.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
bandwidth 75000
ip address 12.12.12.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet1/0
bandwidth 50000
ip address 13.13.13.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 5.0.0.0
network 11.0.0.0
network 12.0.0.0
network 13.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
R2
R2#sh run
Building configuration...
Current configuration : 1077 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
interface FastEthernet0/0
ip address 11.11.11.2 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
no ip address
speed 100
full-duplex
!
interface FastEthernet1/0
ip address 14.14.14.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 11.0.0.0
network 14.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R3
R3#sh run
Building configuration...
Current configuration : 1104 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
interface FastEthernet0/0
ip address 15.15.15.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
bandwidth 75000
ip address 12.12.12.2 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet1/0
no ip address
shutdown
duplex auto
speed auto
!
router eigrp 10
network 12.0.0.0
network 15.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
control-plane
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R4
R4#sh run
Building configuration...
Current configuration : 1105 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
!
!
interface FastEthernet0/0
ip address 16.16.16.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
bandwidth 50000
ip address 13.13.13.2 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 13.0.0.0
network 16.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
Configure accordingly on gns3 as shown on above. Now from router R1 having 3 path to reach router R5 loopback addreass.
Let us check following command out put.
R1#sh ip eigrp topology
IP-EIGRP Topology Table for AS(10)/ID(5.5.5.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 5.0.0.0/8, 1 successors, FD is 128256
via Summary (128256/0), Null0
P 5.5.5.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 6.0.0.0/8, 1 successors, FD is 158720
via 11.11.11.2 (158720/156160), FastEthernet0/0
via 13.13.13.2 (184320/156160), FastEthernet1/0
via 12.12.12.2 (167168/156160), FastEthernet0/1
P 11.0.0.0/8, 1 successors, FD is 28160
via Summary (28160/0), Null0
P 11.11.11.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P 12.0.0.0/8, 1 successors, FD is 36608
via Summary (36608/0), Null0
P 12.12.12.0/24, 1 successors, FD is 36608
via Connected, FastEthernet0/1
P 13.0.0.0/8, 1 successors, FD is 53760
via Summary (53760/0), Null0
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 13.13.13.0/24, 1 successors, FD is 53760
via Connected, FastEthernet1/0
P 14.0.0.0/8, 1 successors, FD is 30720
via 11.11.11.2 (30720/28160), FastEthernet0/0
P 15.0.0.0/8, 1 successors, FD is 33280
via 11.11.11.2 (33280/30720), FastEthernet0/0
via 13.13.13.2 (58880/30720), FastEthernet1/0
via 12.12.12.2 (39168/28160), FastEthernet0/1
P 16.0.0.0/8, 1 successors, FD is 33280
via 11.11.11.2 (33280/30720), FastEthernet0/0
via 13.13.13.2 (56320/28160), FastEthernet1/0
via 12.12.12.2 (41728/30720), FastEthernet0/1
see the for loopback 6.6.6.0 network we have three path marked in red.
now run sh ip route 6.6.6.0
R1#sh ip route 6.6.6.0
Routing entry for 6.0.0.0/8
Known via "eigrp 10", distance 90, metric 158720, type internal
Redistributing via eigrp 10
Last update from 11.11.11.2 on FastEthernet0/0, 00:21:08 ago
Routing Descriptor Blocks:
* 11.11.11.2, from 11.11.11.2, 00:21:08 ago, via FastEthernet0/0
Route metric is 158720, traffic share count is 1
Total delay is 5200 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
It is now showing only one path in the routing table. The metric is the lowest one. By default in EIGRP unequal load sharing does not happen.
Now see the trace route below.
R1#traceroute 6.6.6.6
Type escape sequence to abort.
Tracing the route to 6.6.6.6
1 11.11.11.2 80 msec 72 msec 16 msec
2 14.14.14.2 60 msec 24 msec 44 msec
So for unequal load sharing we have to use variance command as below.
R1#sh run | b router
router eigrp 10
variance 3
network 5.0.0.0
network 11.0.0.0
network 12.0.0.0
network 13.0.0.0
auto-summary
now check the IP route output below.
R1#sh ip route 6.6.6.0
Routing entry for 6.0.0.0/8
Known via "eigrp 10", distance 90, metric 158720, type internal
Redistributing via eigrp 10
Last update from 12.12.12.2 on FastEthernet0/1, 00:01:28 ago
Routing Descriptor Blocks:
13.13.13.2, from 13.13.13.2, 00:01:28 ago, via FastEthernet1/0
Route metric is 184320, traffic share count is 69
Total delay is 5200 microseconds, minimum bandwidth is 50000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
12.12.12.2, from 12.12.12.2, 00:01:28 ago, via FastEthernet0/1
Route metric is 167168, traffic share count is 76
Total delay is 5200 microseconds, minimum bandwidth is 75187 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
* 11.11.11.2, from 11.11.11.2, 00:01:28 ago, via FastEthernet0/0
Route metric is 158720, traffic share count is 80
Total delay is 5200 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
Now you can find three path on the routing table to reach 6.6.6.0 network. actually variance 3 multiply 3 with lowest metric. now check the trace route below.
R1#traceroute 6.6.6.6
Type escape sequence to abort.
Tracing the route to 6.6.6.6
1 13.13.13.2 68 msec
12.12.12.2 84 msec
11.11.11.2 40 msec
2 16.16.16.2 40 msec
15.15.15.2 28 msec
14.14.14.2 28 msec
It is awesome. You can try this on your lab.
Thanks
R1
R1#sh run
Building configuration...
Current configuration : 1224 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
!
archive
log config
hidekeys
!
!
ip tcp synwait-time 5
ip ssh version 1
!
interface Loopback0
ip address 5.5.5.5 255.255.255.0
!
interface FastEthernet0/0
ip address 11.11.11.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
bandwidth 75000
ip address 12.12.12.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet1/0
bandwidth 50000
ip address 13.13.13.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 5.0.0.0
network 11.0.0.0
network 12.0.0.0
network 13.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
R2
R2#sh run
Building configuration...
Current configuration : 1077 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
interface FastEthernet0/0
ip address 11.11.11.2 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
no ip address
speed 100
full-duplex
!
interface FastEthernet1/0
ip address 14.14.14.1 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 11.0.0.0
network 14.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R3
R3#sh run
Building configuration...
Current configuration : 1104 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
interface FastEthernet0/0
ip address 15.15.15.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
bandwidth 75000
ip address 12.12.12.2 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet1/0
no ip address
shutdown
duplex auto
speed auto
!
router eigrp 10
network 12.0.0.0
network 15.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
control-plane
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
R4
R4#sh run
Building configuration...
Current configuration : 1105 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
no ip icmp rate-limit unreachable
ip cef
!
!
no ip domain lookup
!
multilink bundle-name authenticated
!
!
!
archive
log config
hidekeys
!
!
!
!
ip tcp synwait-time 5
ip ssh version 1
!
!
!
!
interface FastEthernet0/0
ip address 16.16.16.1 255.255.255.0
speed 100
full-duplex
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
bandwidth 50000
ip address 13.13.13.2 255.255.255.0
duplex auto
speed auto
!
router eigrp 10
network 13.0.0.0
network 16.0.0.0
auto-summary
!
ip forward-protocol nd
!
!
no ip http server
no ip http secure-server
!
no cdp log mismatch duplex
!
!
control-plane
!
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
Configure accordingly on gns3 as shown on above. Now from router R1 having 3 path to reach router R5 loopback addreass.
Let us check following command out put.
R1#sh ip eigrp topology
IP-EIGRP Topology Table for AS(10)/ID(5.5.5.5)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 5.0.0.0/8, 1 successors, FD is 128256
via Summary (128256/0), Null0
P 5.5.5.0/24, 1 successors, FD is 128256
via Connected, Loopback0
P 6.0.0.0/8, 1 successors, FD is 158720
via 11.11.11.2 (158720/156160), FastEthernet0/0
via 13.13.13.2 (184320/156160), FastEthernet1/0
via 12.12.12.2 (167168/156160), FastEthernet0/1
P 11.0.0.0/8, 1 successors, FD is 28160
via Summary (28160/0), Null0
P 11.11.11.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P 12.0.0.0/8, 1 successors, FD is 36608
via Summary (36608/0), Null0
P 12.12.12.0/24, 1 successors, FD is 36608
via Connected, FastEthernet0/1
P 13.0.0.0/8, 1 successors, FD is 53760
via Summary (53760/0), Null0
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 13.13.13.0/24, 1 successors, FD is 53760
via Connected, FastEthernet1/0
P 14.0.0.0/8, 1 successors, FD is 30720
via 11.11.11.2 (30720/28160), FastEthernet0/0
P 15.0.0.0/8, 1 successors, FD is 33280
via 11.11.11.2 (33280/30720), FastEthernet0/0
via 13.13.13.2 (58880/30720), FastEthernet1/0
via 12.12.12.2 (39168/28160), FastEthernet0/1
P 16.0.0.0/8, 1 successors, FD is 33280
via 11.11.11.2 (33280/30720), FastEthernet0/0
via 13.13.13.2 (56320/28160), FastEthernet1/0
via 12.12.12.2 (41728/30720), FastEthernet0/1
see the for loopback 6.6.6.0 network we have three path marked in red.
now run sh ip route 6.6.6.0
R1#sh ip route 6.6.6.0
Routing entry for 6.0.0.0/8
Known via "eigrp 10", distance 90, metric 158720, type internal
Redistributing via eigrp 10
Last update from 11.11.11.2 on FastEthernet0/0, 00:21:08 ago
Routing Descriptor Blocks:
* 11.11.11.2, from 11.11.11.2, 00:21:08 ago, via FastEthernet0/0
Route metric is 158720, traffic share count is 1
Total delay is 5200 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
It is now showing only one path in the routing table. The metric is the lowest one. By default in EIGRP unequal load sharing does not happen.
Now see the trace route below.
R1#traceroute 6.6.6.6
Type escape sequence to abort.
Tracing the route to 6.6.6.6
1 11.11.11.2 80 msec 72 msec 16 msec
2 14.14.14.2 60 msec 24 msec 44 msec
So for unequal load sharing we have to use variance command as below.
R1#sh run | b router
router eigrp 10
variance 3
network 5.0.0.0
network 11.0.0.0
network 12.0.0.0
network 13.0.0.0
auto-summary
now check the IP route output below.
R1#sh ip route 6.6.6.0
Routing entry for 6.0.0.0/8
Known via "eigrp 10", distance 90, metric 158720, type internal
Redistributing via eigrp 10
Last update from 12.12.12.2 on FastEthernet0/1, 00:01:28 ago
Routing Descriptor Blocks:
13.13.13.2, from 13.13.13.2, 00:01:28 ago, via FastEthernet1/0
Route metric is 184320, traffic share count is 69
Total delay is 5200 microseconds, minimum bandwidth is 50000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
12.12.12.2, from 12.12.12.2, 00:01:28 ago, via FastEthernet0/1
Route metric is 167168, traffic share count is 76
Total delay is 5200 microseconds, minimum bandwidth is 75187 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
* 11.11.11.2, from 11.11.11.2, 00:01:28 ago, via FastEthernet0/0
Route metric is 158720, traffic share count is 80
Total delay is 5200 microseconds, minimum bandwidth is 100000 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 2
Now you can find three path on the routing table to reach 6.6.6.0 network. actually variance 3 multiply 3 with lowest metric. now check the trace route below.
R1#traceroute 6.6.6.6
Type escape sequence to abort.
Tracing the route to 6.6.6.6
1 13.13.13.2 68 msec
12.12.12.2 84 msec
11.11.11.2 40 msec
2 16.16.16.2 40 msec
15.15.15.2 28 msec
14.14.14.2 28 msec
It is awesome. You can try this on your lab.
Thanks
