You are designing a network using multipoint GRE tunnels and need to be able to detect when connectivity between the GRE tunnel endpoints is broken.
Which statement is true about configuring keepalives for multipoint GRE tunnels?
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A. B. C. D.D.
Multipoint Generic Routing Encapsulation (GRE) tunnels are used to connect multiple remote sites over an IP network. These tunnels encapsulate packets from multiple sources and route them over the same virtual private network ( VPN) or service provider network. In such a network, it is crucial to ensure that connectivity between the GRE tunnel endpoints is maintained, and the network remains functional.
To detect when connectivity between GRE tunnel endpoints is broken, keepalive mechanisms can be used. Keepalives are packets that are sent over the GRE tunnel at regular intervals to verify that the connection is still active. If the keepalive packet is not received within a certain period, the connection is assumed to be broken, and the network administrator can take appropriate action.
Regarding the statement that is true about configuring keepalives for multipoint GRE tunnels:
A. The keepalive timer values on the routers must have the same value. This statement is true. To ensure that both routers can detect the loss of connectivity, the keepalive timer values on both endpoints must be the same. If one endpoint sends keepalives more frequently than the other, the second endpoint may assume that the first endpoint is no longer reachable, even though it is still operational.
B. Both routers must support GRE tunnel keepalives. This statement is not entirely true. Although it is ideal for both routers to support GRE tunnel keepalives, it is not always necessary. Even if one router does not support GRE tunnel keepalives, the other router can still send keepalives, and the connectivity between the endpoints can still be maintained.
C. No configuration is required to detect when connectivity is broken between the GRE tunnel endpoints. This statement is false. Without configuring keepalive packets, the routers have no means to detect when the connection is broken.
D. GRE tunnel keepalives will not detect when connectivity is broken between the GRE tunnel endpoints. This statement is false. GRE tunnel keepalives are an effective way to detect when connectivity between the GRE tunnel endpoints is broken.
In summary, to detect when connectivity between GRE tunnel endpoints is broken, keepalive packets must be configured on both endpoints, and the keepalive timer values on both routers must be the same. Even if one endpoint does not support GRE tunnel keepalives, the other endpoint can still send keepalives to maintain connectivity.