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Chapter 10

Route Optimization

router rip

which enables the RIP routing process.

redistribute eigrp 10

which tells the router to take routes learned via EIGRP AS 10 and re-
advertise them via RIP.

network 8.0.0.0

where network is the network that is part of the RIP routing process.

default-metric 3

where 3 is to be used as the default metric (hop count) when other routing
protocols are injected into RIP.

At this point, both RouterA and RouterC can see each other's routes. Also

note that it would have been possible to do a one-way redistribution. A one-
way redistribution is where one routing protocol is redistributed into
another, but not vice versa. For example, if we had omitted the RouterB con-
figuration command redistribute rip under the router eigrp 10 sec-
tion of the configuration, then routes learned via RIP would not have been
re-advertised by EIGRP. In some situations, it is good design practice to use
one-way redistribution, to avoid routing loops. This is of particular impor-
tance when a router's split-horizon function (which prevents routing loops)
has been disabled.

EIGRP and IGRP Route Redistribution

We mentioned earlier that EIGRP and IGRP use the same metrics and can
therefore automatically redistribute their routes into each other without the
need for manual redistribution, which was required in the previous example.
The one caveat is that the EIGRP and IGRP AS must be the same.

For example, consider a variation on our original scenario. This time,

Company B's network uses IGRP, as shown in Figure 10.5.

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