Cisco CCNP BSCI Exam Tutorial OSPF Route Redistribution Review
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Cisco CCNP/BSCI Exam Guide: Understanding OSPF Route Redistribution
Introduction
Mastering OSPF route redistribution is crucial for the BSCI exam. Let's delve into the essential concepts with insights from Chris Bryant, CCIE
12933.
Key Concepts
Route redistribution in OSPF is rich with details that are vital both for the exam and practical application. Here's a streamlined review of the fundamentals to help you succeed.
Identifying ABR and ASBR
To determine if a router is an Area Border Router (ABR) or Autonomous System Boundary Router (ASBR), use the command:
```bash
show ip ospf
```
This command not only reveals its status but also any routes being redistributed into OSPF.
Redistributing Routes
When redistributing routes like RIP into OSPF, remember the importance of the "subnets" option. It ensures subnets are included during redistribution. Conversely, when routing OSPF into RIP, a seed metric is essential. Although OSPF assigns a default metric of 20 to redistributed routes, no seed metric is needed.
Example Configuration
```bash
R1(config)
router ospf 1
R1(config-router)redistribute connected
Only classful networks will be redistributed
R1(config-router)redistribute connected subnets
R1(config-router)redistribute rip subnets
R1(config-router)router rip
R1(config-router)redistribute connected metric 1
R1(config-router)redistribute ospf 1 metric 1
```E2 vs. E1 Routes
By default, routes redistributed into OSPF are classified as E2, meaning their metric reflects only the cost from the ASBR to the destination. In contrast, E1 routes account for the entire path cost, including from the local router to the destination.
Example Routes
```plaintext
O E2 5.1.1.1 [110/20] via 172.34.34.3, Ethernet0
O E2 6.1.1.1 [110/20] via 172.34.34.3, Ethernet0
```
Setting E1 Routes
To set routes as E1 during redistribution, use the `metric-type` option:
```bash
R1(config)
router ospf 1
R1(config-router)redistribute rip subnets metric-type 1
```Reviewing R4's routing table will then display these as E1 routes:
```plaintext
O E1 5.1.1.1 [110/94] via 172.34.34.3, Ethernet0
O E1 6.1.1.1 [110/94] via 172.34.34.3, Ethernet0
```
Final Tips
Achieving success in the BSCI exam and gaining your CCNP certification requires a thorough understanding of the details involved in OSPF route redistribution. Keep practicing different scenarios using your CCNA/CCNP lab or rack rental to sharpen your skills. Good luck!
You can find the original non-AI version of this article here: Cisco CCNP BSCI Exam Tutorial OSPF Route Redistribution Review.
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