Which two statements about GRE tunnels are true? (Choose two.)
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A. B. C. D.AD
GRE is a tunneling protocol that can encapsulate a wide variety of Network Layer protocol packet types inside IP tunnels, such as IPX and AppleTalk. GRE tunnels are also commonly used to tunnel IPv6 and MPLS protocol traffic over an IP transport network. GRE adds 24 bytes of overhead to each packet.
GRE (Generic Routing Encapsulation) tunnels are used to encapsulate one protocol inside another protocol to create a virtual point-to-point link. Here are the correct statements about GRE tunnels:
B. GRE can provide encrypted communication: GRE does not provide any encryption by default, but it can be used in combination with other encryption protocols, such as IPsec, to provide secure communication between endpoints. This makes GRE an attractive choice for creating VPNs (Virtual Private Networks) between geographically dispersed networks.
D. GRE can be used to tunnel IPv6 traffic: GRE can encapsulate any network layer protocol, including IPv6. This allows IPv6 packets to be transported over IPv4 networks, which are still predominant in many parts of the world.
A. GRE can be used to tunnel non-IP protocols, such as IPX: This statement is false. GRE is an IP-based tunneling protocol and can only encapsulate IP traffic. Therefore, it cannot be used to tunnel non-IP protocols like IPX.
C. GRE adds overhead of 16 bytes per packet: This statement is partially true. GRE encapsulation adds an additional header of 24 bytes to the original packet, which includes a 4-byte GRE header, a 20-byte IP header, and a variable-length payload. However, the actual overhead depends on the size of the original packet, and it may vary between different implementations. Therefore, it is difficult to define a fixed value for the overhead added by GRE encapsulation.