Nectar: A dtn routing protocol based on neighborhood contact history

This is an Employment Paper at the sac2009 meeting. Create a neighbor index based on the historical contact information between nodes to determine the most appropriate message forwarding path. Simulation Based on Dartmouth College's actual network scenario shows that nectar can transmit more messages and consume less network resources compared with infectious routes and Prophet routes.

Nectar RoutingAlgorithmIn general, there are three steps: 1. Ni (neighborhood index) calculation; 2. Message debugging policy; 3. Message discarding policy.

When node I and node J meet each other for the first time, the NI value of each other is set to 1. During the period when I and j are in contact, both the Ni value and the contact counter (contact counter) Keep linear growth. Then, both node I and node J update the Ni value of other nodes not in the communication range. If node J has a better Ni value for the same target node D, the NI value from I to the target node is calculated using the following method:

If node I already has a path to node D and node J has a better Ni value, then n (I, d) is updated in a weighted manner, to reduce the impact of new information and prevent interference of illegal information.

The message scheduling policy determines the priority of messages transmitted in the message storage buffer. When node I establishes a connection with node J, node I preferentially sends the node whose destination node is J, and vice versa. After performing this step, the node updates each other's Ni, and then sends a message that the next hop node is the other node.

To prevent repeated copies of the same message, after a message is transmitted, the node stores the header of the message in another storage location. The storage time is ttl_deleted. [Question: What is the purpose?]

Nectar can be operated in the form of a infectious route. If the difference between the node TTL and the maximum TTL value is less than a certain threshold value of minepidemiclevel, the message is transmitted to all its neighbors.

To prevent buffer congestion, when minepidemiclevel <(a-TTL) <maxepidemiclevel, the node receives this message only when the buffer usage is lower than a certain threshold value. You can set different minepidemiclevel & maxepidemiclevel values for messages with different priorities.

The message discard policy mainly takes into account two factors: the number of copies of the message and the time elapsed since the message was received. The message discard policy tends to retain the recently received messages and messages that are rarely forwarded. Therefore, messages with a higher mage will be discarded first:

 

Message package structure:

My questions:

1, in the message scheduling algorithm, the author mentioned that after delivering a message to its destination, nodes maintain the headers 'message for ttl_deleted time slot in a different storage area to avoid loading ing redundant copies of the same messages.

What is headers 'message? Is that messages 'headers?