A closely related question is who will receive credit for forwarding a message. Ideally, any node who has ever tried to forward a message should be compensated because forwarding a message will incur a cost to the node, no matter successful or not. However, a forwarded message may be corrupted on the link, and there is no way to verify that the forwarding action does occur. Although some local wireless networks such as IEEE do provide link layer acknowledgments, such acknowledgment schemes are not universal and we refrain from changing basic network functions. Given this decision, the credit that a node receives will depend on whether or not its forwarding.
