Configuring OSPF for Point-to-Multipoint Frame Relay Network
Question
You are deploying OSPF on a point-to-multipoint Frame Relay network.
The remote sites do not need to be able to communicate with each other and there are a relatively small number of sites (scaling is not a concern)
How should you configure OSPF for this topology to minimize the additional routing information injected into the network and keep the configuration size and complexity to a minimum?
Answers
Explanations
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A. B. C. D.B.
When deploying OSPF on a point-to-multipoint Frame Relay network, the main goal is to minimize the additional routing information injected into the network while keeping the configuration size and complexity to a minimum.
Option A: Configure the link at the hub router as OSPF point-to-multipoint and at the remote routers as OSPF point-to-point. This option is a good choice for a small number of remote sites because it minimizes the routing information injected into the network. OSPF point-to-multipoint is used on the hub router to minimize the number of adjacencies created, while OSPF point-to-point is used on the remote routers to keep the routing information to a minimum. The downside of this option is that it requires manual configuration of each remote router as a point-to-point link.
Option B: Configure the link as OSPF broadcast and configure the hub router to always be the designated router. This option is not recommended because it injects additional routing information into the network. OSPF broadcast is not a suitable choice for a point-to-multipoint network, as it creates a full mesh of adjacencies, which can be inefficient and resource-intensive. In addition, configuring the hub router as the designated router would result in extra overhead.
Option C: Configure the link as OSPF nonbroadcast and manually configure each of the remote sites as a neighbor. This option is also a good choice for a small number of remote sites because it minimizes the additional routing information injected into the network. OSPF nonbroadcast is used to minimize the number of adjacencies created and manual configuration of each remote site as a neighbor ensures that the routing information is kept to a minimum. The downside of this option is that it requires manual configuration of each remote router as a neighbor.
Option D: Configure the link as OSPF broadcast and configure a mesh group towards the remote routers. This option is not recommended because it injects additional routing information into the network. OSPF broadcast is not a suitable choice for a point-to-multipoint network, as it creates a full mesh of adjacencies, which can be inefficient and resource-intensive. In addition, configuring a mesh group would result in extra overhead.
Therefore, the best option to configure OSPF for a point-to-multipoint Frame Relay network is to use OSPF point-to-multipoint on the hub router and OSPF point-to-point on the remote routers (Option A). This option minimizes the routing information injected into the network and keeps the configuration size and complexity to a minimum.
