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Chapter 6
IGRP and EIGRP
[170/40542208] via 172.16.131.82, 11:40:32, ATM6/0/0.3114
[170/40542208] via 172.16.131.74, 11:41:32, ATM6/0/0.3113
D EX 172.16.52.192/26
[170/2202112] via 172.16.131.82, 11:41:27, ATM6/0/0.3114
D EX 172.16.41.216/29
[170/46232832] via 172.16.131.82, 11:41:28, ATM6/0/0.3114
D EX 172.16.38.200/30
[170/2176512] via 172.16.131.82, 11:41:27, ATM6/0/0.3114
D EX 172.16.237.0/29
[170/40542208] via 172.16.131.82, 11:41:32, ATM6/0/0.3114
[170/40542208] via 172.16.131.74, 11:41:32, ATM6/0/0.3113
D 172.16.236.0/24
[90/311808] via 172.16.131.82, 11:41:32, ATM6/0/0.3114
[90/311808] via 172.16.131.74, 11:41:32, ATM6/0/0.3113
D 172.16.235.0/24
[90/311808] via 172.16.131.82, 11:41:32, ATM6/0/0.3114
There are internal routes and external routes in this routing table. The
external routes are flagged with EX, while the internal routes have no flag.
The D stands for an EIGRP learned route.
While redistribution allows multiple protocols to share routing informa-
tion, it can cause routing loops, slow convergence, and inconsistent route
information. This is caused by the different algorithms and methods used by
each protocol. It is not a good practice to redistribute bi-directionally. For
example, if you have both EIGRP 10 using IP-EIGRP and EIGRP 20 using
AT-EIGRP routing sessions, then bi-directional redistribution would occur if
you entered redistribution commands under each protocol session. Here is
an example:
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#router eigrp 10
Router(config-router)#redistribute eigrp 20
Router(config-router)#router eigrp 20
Router(config-router)#redistribute eigrp 10
Router(config-router)#^Z
Router#
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