Redistributing into OSPF
You redistribution into OSPF in the same way as in the other protocols. The metric for an OSPF route is a derivative of the bandwidths of the links contained in the route. Set the default metric in OSPF to 10 Mbps as follows:
R3(config-router)#default-metric 10
There are no other options. The metric can have a value of 1â16,777,214, with 1 being 100 Mbps (assuming default settings).
Note
If you do not specify a default metric or a metric on the redistribute
command line, OSPF will assign a
metric of 20 to all redistributed routes, except those from BGP, which
will be assigned a metric of 1.
While all redistributed routes are external, OSPF supports two types
of external routes, which are cleverly described as
type-1 and type-2 external
routes. Type-1 routes are designated with O
E1
in the routing table, while type-2 routes are designated with
O E2
. E1
routes include the metric as set at the point
of redistribution, plus the metric of all the links within the OSPF
autonomous system. E2
routes only
include the metric set at the point of redistribution. Figure 11-4 illustrates how the OSPF metrics
change throughout a simple network depending on the external route type in
use.
Figure 11-4. OSPF external route types
Redistribution into OSPF defaults to type-2 routes. Which type should you use? That depends on your needs at the time. Generally, in smaller networks ...
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