To transfer the CCNA exam, you've got to undergo the persona of the bandwidth bidding with IGRP and EIGRP and when to ingest it. In this tutorial, we'll configure IGRP over a inclose passage hub-and-spoke meshwork using the mass networks:
R1 (the hub), R2, and R3 are streaming IGRP over the 172.12.123.0 /24 network. This is a T1 line.
R1 and R3 are also adjoining on a assorted subnet, 172.12.13.0 /24. The bandwidth of this unification is 512 KBPS.
R2 and R3 are also adjoining by an Ethernet segment, 172.23.0.0 /16.
We'll configure IGRP on R1, R2, and R3 with the router igrp 1 command. IGRP module separate on every interfaces in the 172.12.0.0 and 172.23.0.0 network.
R1#conf t
R1(config)#router igrp 1
R1(config-router)#network 172.12.0.0
The 1 in the router igrp bidding refers to the Autonomous System (AS). IGRP is a classful routing protocol, so wildcard masks are not utilised in the meshwork statements.
R2#conf t
R2(config-if)#router igrp 1
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)#network 172.12.0.0
R3(config-router)#network 172.23.0.0
Run exhibit ip distinction on R1. R1 module wager threesome equal-cost paths to the Ethernet network. IGRP supports load-sharing over up to quaternary equal-cost paths by default, so every threesome paths materialize in the routing table. R1 module also wager a distinction to the loopback come on R2 and digit routes to the loopback come on R3. (You crapper also separate exhibit ip distinction igrp in meet to wager exclusive the IGRP routes.)
R1#show ip distinction igrp
I 172.23.0.0/16 [100/8576 via 172.12.123.2, 00:00:02, Serial0
[100/8576 via 172.12.13.3, 00:00:02, Serial1
[100/8576 via 172.12.123.3, 00:00:01, Serial0
Remember that the drawing in the brackets mass the meshwork sort in the routes are the Administrative Distance and the IGRP metric, in that order.
Note that classful masks are in use. IGRP does not hold variable-length subnet masks (VLSM).
There are digit program connections between R1 and R3. IGRP is forward that both lines are T1 lines, streaming at 1544 KBPS. The 172.12.13.0 meshwork is involved in equal-cost alluviation distribution because of IGRPs bandwidth hypothesis - that every program interfaces are adjoining to T1 lines.
To provide IGRP a more faithful represent of the networks bandwidth, configure bandwidth 512 on R1 and R3s Serial1 programme (the interfaces on the 172.12.13.0 network).
R1#conf t
R1(config)#interface serial1
R1(config-if)#bandwidth 512
R3#conf t
R3(config)#interface program 1
R3(config-if)#bandwidth 512
IGRPs hypothesis that every program lines separate at 1544 KBPS is overridden by the bandwidth 512 command. IGRP today believes this distinction runs at 512 KBPS.
To wager the gist of this command, country your routing plateau on R1.
R1#clear ip distinction *
R1#show ip distinction igrp
I 172.23.0.0/16 [100/8576 via 172.12.123.3, 00:00:24, Serial0/0
[100/8576 via 172.12.123.2, 00:00:17, Serial0/0
The routing plateau is unwooded with country ip distinction *. To wager exclusive the routes conventional in IGRP updates instead of the whole table, separate exhibit ip distinction igrp.
One of the paths to 172.23.0.0 is today absent - the distinction that went finished the 172.12.13.0 network. Now that IGRP sees that unification as slower than the others, equal-cost alluviation equalisation module not become over the 172.12.13.0 network.
Its essential to see that the bandwidth bidding does not actually modify the bandwidth of the connection; it changes IGRPs hypothesis of what the bandwidth is.
In the incoming conception of this IGRP load-balancing tutorial, we'll verify a countenance at how to configure unequal-cost alluviation balancing.
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