Which of these is a reason to carry routes that originate outside your network in an EGP, such as BGP, rather than in your IGP, such as OSPF, EIGRP, or IS-IS?
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A. B. C. D.B.
When designing a network, one of the important considerations is how to handle routing information. Routing protocols are used to exchange routing information between routers so that they can determine the best path to a destination network. There are two types of routing protocols: Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs).
IGPs, such as OSPF, EIGRP, or IS-IS, are used to distribute routing information within a single autonomous system (AS) or network. These protocols are designed to be fast and efficient, with a focus on quickly converging the routing tables of all routers within the AS. However, they are not well-suited for distributing routing information outside of the AS.
EGPs, such as BGP, are used to exchange routing information between different autonomous systems (ASes) or networks. They are designed to be more scalable and flexible than IGPs, and to provide more control over routing policies. BGP is commonly used in large service provider networks and in enterprise networks that have multiple connections to the Internet.
Now, let's consider the reasons to carry routes that originate outside your network in an EGP, such as BGP, rather than in your IGP, such as OSPF, EIGRP, or IS-IS:
A. To provide better control over the distribution of the default route inside your network: By carrying external routes in BGP, you can have more control over how these routes are distributed within your network. For example, you can use BGP attributes to manipulate the path selection process and to influence which routes are preferred over others.
B. To prevent failures outside your network from impacting your internal network operation: If you rely solely on an IGP to distribute external routes, you may be vulnerable to failures outside your network that can impact your internal network operation. By using BGP to carry external routes, you can implement policies that protect your internal network from external failures, such as filtering out certain routes or using BGP communities to influence the way routes are advertised.
C. To provide faster convergence to destinations outside your network: If your network has multiple connections to the Internet or to other networks, using BGP to distribute external routes can provide faster convergence to destinations outside your network. BGP is designed to be more scalable and to handle a larger number of routes than IGPs, which can result in faster convergence times.
D. To provide a growth path for the core of your network: As your network grows and you add new connections to other networks, using BGP to carry external routes can provide a growth path for the core of your network. BGP is designed to be flexible and to support a wide range of routing policies, which can help you adapt to changing business requirements and network topologies.
In summary, carrying routes that originate outside your network in an EGP, such as BGP, rather than in your IGP, such as OSPF, EIGRP, or IS-IS, can provide better control over route distribution, protect your internal network from external failures, provide faster convergence times, and provide a growth path for the core of your network.