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Cisco CCNA Examination Tutorial: IGRP And Equivalent Expense Load Balancing
To go the CCNA Examination, you’ve obtained to be aware of the position of your bandwidth command with IGRP and EIGRP and when to employ it. On this tutorial, we’ll configure IGRP more than a frame relay hub-and-spoke network applying the following networks:
R1 (the hub), R2, and R3 are operating IGRP about the 172.12.123.0 /24 community. This is the T1 line.
R1 and R3 can also be related on another subnet, 172.12.thirteen.0 /24. The bandwidth of the connection is 512 KBPS.
R2 and R3 will also be related by an Ethernet phase, 172.23.0.0 /16.
We’ll configure IGRP on R1, R2, and R3 Along with the router igrp 1 command. IGRP will operate on all interfaces from the 172.twelve.0.0 and 172.23.0.0 community.
R1#conf t
R1(config)#router igrp one
R1(config-router)#community 172.twelve.0.0
The 1 from the router igrp command refers back to the Autonomous Method (AS). IGRP is really a classful routing protocol, so wildcard masks are not Utilized in the network statements.
R2#conf t
R2(config-if)#router igrp one
R2(config-router)#network 172.12.0.0
R2(config-router)#network 172.23.0.0
R3#conf t
R3(config-if)#router igrp 1
R3(config-router)#community 172.12.0.0
R3(config-router)#community 172.23.0.0
Operate exhibit ip route on R1. R1 will see a few equivalent-Charge paths to the Ethernet network. IGRP supports load-sharing over as much as 4 equal-Value paths by default, so all three paths show up while in the routing desk. R1 may even see a route to the loopback deal with on R2 and two routes for the loopback handle on R3. (You can even operate present ip route igrp as a way to see just the IGRP routes.)
R1#exhibit ip route igrp
I 172.23.0.0/sixteen [a hundred/8576] via 172.12.123.2, 00:00:02, Serial0
[100/8576] by using 172.twelve.thirteen.three, 00:00:02, Serial1
[a hundred/8576] via 172.12.123.three, 00:00:01, Serial0
Bear in mind the numbers from the brackets following the community quantity in the routes are the executive Distance plus the IGRP metric, in that order.
Be aware that classful masks are in use. IGRP won't support variable-duration subnet masks (VLSM).
There's two serial connections among R1 and R3. IGRP is assuming that equally strains are T1 lines, jogging at 1544 KBPS. The 172.12.13.0 network is taking part in equal-Price load sharing as a consequence of IGRPs bandwidth assumption – that every one serial interfaces are linked to T1 strains.
To present IGRP a more exact picture in the networks bandwidth, configure bandwidth 512 on R1 and R3s Serial1 interface (the interfaces on the 172.12.thirteen.0 community).
R1(config)#interface serial1
R1(config-if)#bandwidth 512
R3(config)#interface serial one
R3(config-if)#bandwidth 512
IGRPs assumption that every one serial traces run at 1544 KBPS is overridden from the bandwidth 512 command. IGRP now believes this line runs at 512 KBPS.
To begin to see the outcome of the command, obvious your routing table on R1.
R1#distinct ip route *
I 172.23.0.0/16 [a hundred/8576] by way of 172.twelve.123.three, 00:00:24, Serial0/0
[one hundred/8576] by way of 172.twelve.123.2, 00:00:seventeen, Serial0/0
The routing table is cleared https://socialhattori.com/ with apparent ip route *. To determine only the routes been given in IGRP updates in lieu of your entire desk, run clearly show ip route igrp.
One of many paths to 172.23.0.0 is currently long gone – the route that went in the 172.twelve.thirteen.0 community. Given that IGRP sees that website link as slower in comparison to the Many others, equal-Value load balancing will never occur over the 172.twelve.13.0 network.
Its important to understand that the bandwidth command isn't going to truly change the bandwidth of the connection; it variations IGRPs assumption of just what the bandwidth is.
In the subsequent section of this IGRP load-balancing tutorial, we’ll Consider the way to configure unequal-Price load balancing.