6. MARCO DE REFERENCIA
6.2 MARCO LEGAL
Task 3: Adjusting EIGRP operation over a multipoint WAN interface
What is an EIGRP split horizon?
How can an EIGRP split horizon behavior be changed on a
WAN multipoint interface?
Task 4Deploying EIGRP unequal-cost path load balancing
What do you use to manipulate the path in an EIGRP routing
protocol?
How can you perform path manipulation without using path
control tools?
In the first task, you configured EIGRP over point-to-point WAN interfaces. The EIGRP configuration automatically advertises any additional network that is added to the router. You also added a secondary IP address to the router.
In the second task, you configured EIGRP over a multipoint WAN interface. Again, the EIGRP configuration automatically advertises any additional network that is added to the router. In the third task, you configured additional EIGRP functionalities in order to adjust the EIGRP operation over a multipoint WAN interface. Split horizon was disabled.
In the fourth task, you deployed EIGRP unequal-cost path load balancing. In order to manipulate the path, you changed the metric in EIGRP.
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Verification
Did you have enough information to create the implementation plan?
Do EIGRP-enabled routers form adjacencies on point-to-point and multipoint links after EIGRP is configured?
Do you see all of the EIGRP-advertised networks in the IP routing table as EIGRP routes (after point-to-point and after multipoint configuration respectively)?
What are the changes when split horizon is disabled on the interface?
What is changed to manipulate the path of the packets and what must be implemented to perform unequal-cost load balancing?
A common approach to verifying the implementation process for a routing protocol is to answer the following questions:
Did you have sufficient information to create the implementation plan?
Do EIGRP-enabled routers form adjacencies on point-to-point and multipoint links after EIGRP is configured?
Do you see all of the EIGRP-advertised networks in the IP routing table as EIGRP routes (after point-to-point and multipoint configuration)?
What are the changes when split horizon behavior is disabled on the interface?
What is changed to manipulate the path of the packets and what must be implemented to perform unequal-cost load balancing?
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Checkpoints
Configure EIGRP routing protocol on point-to-point interfaces. Automatically advertise any additional network that is added to the router.
Ensure EIGRP networks are present in the IP routing table. Configure EIGRP routing protocol on multipoint interfaces. Ensure new EIGRP networks are present in the IP routing table. Simulate a connectivity failure between routers R3 and R4 and examine the EIGRP operation afterwards.
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Checkpoints (Cont.)
Change the EIGRP split horizon behavior on the WAN multipoint interface
Adjust the metric to manipulate load balancing.
Simulate a connectivity failure between routers R1 and R3 and examine the EIGRP operation afterwards.
Change the EIGRP metric to manipulate unequal-cost path load balancing.
Verify connectivity.
During the configuration and verification phase, the network operator deals with several checkpoints. After completing all configuration tasks, the network operator has either finished the lab successfully or must perform additional verification and troubleshooting.
With different checkpoints, the network operator can verify for proper configuration. The following checkpoints are used for verification:
Configure the EIGRP routing protocol on point-to-point interfaces. Automatically advertise any additional network that is added to the router. Ensure that EIGRP networks are present in the IP routing table.
Configure the EIGRP routing protocol on multipoint interfaces. Ensure new EIGRP networks are present in the IP routing table.
Simulate a connectivity failure between routers R3 and R4 and examine the EIGRP operation afterwards.
Change the EIGRP split horizon behavior on the WAN multipoint interface. Adjust the metric to manipulate load balancing.
Simulate a connectivity failure between routers R1 and R3 and examine the EIGRP operation afterwards.
Change the EIGRP metric to manipulate unequal-cost path load balancing. Verify connectivity.
Sample Solutions and Alternatives
This topic describes sample solution and other alternatives.
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A Sample Solution
EIGRP is configured on point-to-point and multipoint interfaces. All of the specific IP subnets used in the network are advertised, as well as all new networks added later.
Split horizon is disabled, and the metric is changed in order to provide load balancing and unequal-cost path load-balancing.
The sample solution includes implementation details and details for each task of the
implementation plan. Different solutions are possible and the figure shows a few details of a successful configuration.
Proper implementation includes the following details:
EIGRP is configured on point-to-point and multipoint interfaces.
All of the specific IP subnets used in the network (including all networks added later) are advertised.
Split horizon behavior is disabled and the metric is changed in order provide load balancing and unequal-cost path load balancing.
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Alternative Solutions
A different metric and administrative distance can be applied as well as filtering or static routes can be used in a few segments of the EIGRP network.
EIGRP-specific functionalities do not have many alternative solutions; while another routing protocol can be used, this is not a realistic solution.
A different metric and administrative distance can be applied, as well as filtering or static routes can be used in few segments of the EIGRP network to provide a similar solution.
However, EIGRP-specific functionalities do not have many alternative solutions. To implement a similar solution, another routing protocol can be used, which is not a realistic solution as changing the routing protocol is not the case during fine tuning of the existing protocol.
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Q and A
Why is the selection of a routing protocol important?
What is the difference between point-to-point and multipoint interfaces when configuring an EIGRP?
Why is changing the metric important? How does split horizon work?
The routing protocol, with its metric and administrative distance, exchanges routing updates. It also populates the IP routing table, which is used for destination-based forwarding. Different routing protocols process routing updates in different ways.
When configuring EIGRP on point-to-point interfaces, just two routers are connected to the link. They exchange routing updates. If the interface is a multipoint interface, routing updates received from one neighbor must be sent to another neighbor through the same interface. The metric provides the importance or the quality of the routes within a routing protocol. By manipulating the administrative distance and metric value, you can implement path
manipulation, as well.
Because of the split horizon behavior, the routing updates are not sent back to the interface from which they were received. This breaks the exchange of EIGRP routing updates.
Summary
This topic summarizes the key points that were discussed in this lesson.
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Summary
Configure EIGRP on point-to-point interfaces and advertise all of the specific IP subnets in the network; you should also provide automatic advertising of any additional network that is added to the router.
Configure EIGRP on the multipoint interfaces and advertise all of the specific IP subnets in the network; you should also provide automatic advertising of any additional network that is added to the router.
Manipulate the EIGRP configuration on the multipoint interface by disabling split horizon.
Change the metric in order to deploy unequal-cost path load balancing.