Assigning E1 or E2 Routes in OSPF
Router(config)#router ospf 1 |
Starts the OSPF routing process. |
Router(config-router)#redistribute eigrp 1 metric-type 1 |
Redistributes routes learned from EIGRP autonomous system 1. Routes will be advertised as E1 routes. |
NOTE: If the metric-type argument is not used, routes will be advertised by default in OSPF as E2 routes. E2 routes have a default fixed cost of 20 associated with them, but this value can be changed with the metric keyword. The metric will not change as the route is propagated throughout the OSPF area. E1 routes will have internal area costs added to the seed metric. |
TIP
Use external type 1 (E1) routes when there are multiple Autonomous System Border Routers (ASBRs) advertising an external route to the same autonomous system to avoid suboptimal routing (see Figure 4-1).
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Figure 4-1 Network Topology with Two ASBRs
TIP
Use external type 2 (E2) routes if only one ASBR is advertising an external route to the AS (see Figure 4-2).
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Figure 4-2 Network Topology with One ASBR