/// <summary>Convenience function to instantiate a link-state advertisement packet.</summary>
/// <remarks>The new packet is meant to share a newly-calculated link cost. It is assumed the link cost has just been (re)calculated.</remarks>
/// <param name='src'>The node that is reporting link state.</param>
/// <param name='link'>
/// The link that the new packet will describe. Destination and current link cost will be read from the link.
/// </param>
/// <param name='seq_num'>
/// The new packet will represent the link's status for the <paramref name="seq_num"/>th routing calculation.
/// </param>
public static Packet CreateLinkStateAdvertisement(int seq_num, Node src, Link link, double current_time)
{
return new Packet{
payload_size=Packet.LINK_STATE_ADVERTISEMENT_SIZE,
src=src.ip,
link_dest=link.dest.ip,
link_cost=link.cost,
type=PacketType.LINK_STATE_ADVERTISEMENT,
seq_num=seq_num,
timestamp=current_time
};
}
public Link(EventQueueProcessor eqp, string name, Node src, Node dest, double rate, double prop_delay, Int64 buffer_size)
{
this.eqp = eqp;
this.src = src;
this.dest = dest;
this.rate = rate;
this.name = name;
this.prop_delay = prop_delay;
this.buffer_size = buffer_size;
this.lStatus = new LinkStatus();
this.lStatus.link = this;
this.lStatus.dropped_packets = 0;
this.lStatus.delivered_packets = 0;
this.is_transmitting = false;
this.buffer = new Queue<Packet>();
}
/// <returns>
/// The first hop on the shortest path from <paramref name="this"/> to <paramref name="dest"/> in the <paramref name="shortest_paths_tree"/>
/// </returns>
private Node FirstHopOnShortestPath(Node dest, IDictionary<Node, Node> shortest_paths_tree)
{
if(dest == this) // shouldn't call this
throw new ArgumentException("There is no next hop for a packet destined for this router.", "this");
Node predecessor = shortest_paths_tree[dest];
return predecessor == this ? dest : FirstHopOnShortestPath(predecessor, shortest_paths_tree);
}
