Inside an EIGRP routing area, many occasions there’s a want to regulate the EIGRP route path. For example in eventualities the place we have now 2 or extra equal path hyperlinks to the vacation spot and must configure 1st hyperlink as most well-liked path and relaxation to carry out the backup performance. Beneath documentation enlightens on how EIGRP parameters could be tweaked and most well-liked path choice could also be achieved.
A few of the EIGRP Most well-liked Path manipulation strategies mentioned on this article are:
Although site visitors manipulation could be carried out by way of different elements additionally, some strategies will probably be mentioned on this submit –
The Above Diagram depicts 2 Routers (R1 and R2) linked by way of 2 hyperlinks –
Hyperlink 1 = R1 Fa0/0 to R2 Fa0/0
Hyperlink 2 = R1 Fa0/1 to R2 Fa0/1
R1 and R2 are working EIGRP and configuration of each Routers is shared beneath –
Base Configuration of R1Â
Hostname R1
interface Loopback0
ip deal with 192.168.0.1 255.255.255.0
!
Interface FastEthernet0/0
ip deal with 192.168.12.1 255.255.255.0
!
interface FastEthernet0/1
ip deal with 192.168.112.1 255.255.255.0
!
router eigrp 1
community 192.168.0.0 0.0.255.255
no auto-summary
Base Configuration of R2
Hostname R2
!
interface FastEthernet0/0
ip deal with 192.168.12.2 255.255.255.0
!
interface FastEthernet0/1
ip deal with 192.168.112.2 255.255.255.0
!
router eigrp 1
community 192.168.12.0
community 192.168.112.0
no auto-summary
R2 has 2 equal price paths to community 192.168.0.0/24 ,  1st from interface fa0/0 and a pair ofnd by way of interface fa0/1.
Metric for 192.168.0.0/24 from Fa0/0 Interface of R2
The formulation considers that solely K1 and K3 values (by default) are 1 whereas K2, K4 and K5 are 0 –
The place K1 = Bandwidth and K3 = Delay
Metric = 256 * {(10^7/min BW) + (Whole DLY/10)}
Min BWÂ = minimal BW alongside the trail from fa0/0 of R2 to from Looopback0 of R1
Since Loopback0 of R1 has bandwidth of 8000000 Kbps whereas Fa0/0 of R2 had Bandwidth of 10000 Kbps, therefore min BW will probably be 10000 Kbps
Whole DLYÂ = Sum of Delay alongside the trail from fa0/0 of R2 to from Looopback0 of R1
Since Loopback0 of R1 has delay of 5000 Microseconds whereas Fa0/0 of R2 has delay of 1000 microseconds, therefore Whole DLY will probably be 1000 + 5000 = 6000 Microseconds.
Now,
Metric = 256 * {(10^7/min BW) + (Whole DLY/10)}
= 256 * {(10^7/10000) + (6000/10)}
= 256 * {1000 + 600}
=Â 409600
Metric for 192.168.0.0/24 from Fa0/1 Interface of R2
On this case additionally, the metric values are identical as above resulting in
Metric = 256 * {(10^7/min BW) + (Whole DLY/10)}
= 256 * {(10^7/10000) + (6000/10)}
= 256 * {1000 + 600}
=Â 409600
Now, we’ll devise beneath strategies to make path by way of Interface Fa0/0 of R2 the popular one (Successor) for reaching Loopback 0 (192.168.0.0/24) of R1.The backup (Possible Successor) will probably be by way of Interface Fa0/1 of R2.
EIGRP Most well-liked Path Manipulation by way of Bandwidth
As per requirement depicted within the above diagram to make R2 favor Interface Fa0/0 (Successor) to vacation spot 192.168.0.0/24, Bandwidth parameter (K1 Worth) will probably be tweaked to alter path choice.
As soon as the Bandwidth on Interface is elevated from 10000 Kbps to 100000 Kbps, recalculation for community 192.168.0.0/24 is carried out on R2 which reduces Metric from interface fa0/0 from 409600 to 179200. From now onwards, site visitors destined for community 192.1680.0/24 from R2 will take path by way of Interface Fa0/0.
EIGRP Most well-liked Path Manipulation by way of Delay
As per requirement depicted within the above diagram to make R2 favor Interface Fa0/0 (Successor) to vacation spot 192.168.0.0/24, Delay parameter (K3 Worth) will probably be tweaked to alter path choice.
As soon as the delay on Interface is decreased from 1000 microseconds to 100 microseconds, recalculation for community 192.168.0.0/24 is carried out on R2 which reduces Metric on interface fa0/0 from 409600 to 386560. From now onwards, site visitors destined for community 192.1680.0/24 will take path by way of Interface Fa0/0.
EIGRP Most well-liked Path Manipulation by way of Offset Checklist
Offset Checklist – Possibility 1
For R2 to favor Interface Fa0/0 (Successor) in the direction of vacation spot 192.168.0.0/24, Offset-Checklist could also be configured which henceforth will affect EIGRP path choice by growing the trail metric.
With Offset-list, extra metric will add up for the vacation spot community matching the entry record. As proven within the above diagram, the offset record is utilized on inbound interface fa0/1 of R2. Entry-list 10 matches the realized routes for which metric 1 must be added (on this case entry record 10 matches community 192.168.0.0/24).This methodology provides +1 to the calculated metric on R2 for 192.168.0.0/24.The entire metric worth now turns into 409600 + 1 = 409601.Now the Successor path is by way of Fa0/0 and Possible successor will probably be by way of fa0/1.
Offset Checklist – Possibility 2
Offset record could be utilized on the outgoing interface of promoting router. On this methodology,R1 will add Metric 1 for community 192.168.0.0/24 marketed by way of interface fa0/1 in the direction of R2.By doing so,R2 will be taught metric from fa0/0 (409600) and fa0/1 (409601) .Therefore the Successor path for R2 is by way of Fa0/0 and Possible successor will probably be by way of fa0/1.
EIGRP Most well-liked Path Manipulation by way of Administrative Distance
As we perceive that administrative distance is a vital parameter throughout finest path choice, therefore this may be integrated on native router to control finest path choice from 2 or extra paths of equal price.
Above diagram depicts how Administrative distance could be leveraged for finest path choice. Below the “Router EIGRP 1” command, we alter the EIGRP Administrative Distance from default 90 to 91 for routes acquired from Supply (IP = 192.168.112.1,Wildcard Masks = 0.0.0.0).The command calls entry record 1 which matches the subnet 192.168.0.0/24 (Loopback 0 of  R1).This configuration drives R2 to favor path by way of interface fa0/0 (Administrative distance = 90) and make it the successor whereas maintaining interface fa0/1 as backup.
Proceed Studying:
Redistributed EIGRP Routes not learnt resulting from identical Router ID
Introduction to Administrative Distance
Watch this video for higher understanding:
