/// <summary>
/// Handles the route maintenance.
/// </summary>
private void HandleRouteMaintenance()
{
// if neighbour list is emtpy - return
if (this.Neighbours.Count == 0)
{
return;
}
AodvTable aodvTable = (AodvTable)this.Table;
// after a period of time perform route maintaince via hello messages
if (this.StepCounter % this.periodicHelloUpdateCounter == 0)
{
// broadcast send hello messages to every neighbours
foreach (var neighborId in this.Neighbours.Keys)
{
// enqueue the message for sending
this.SendMessage(
new AodvHelloMessage()
{
Sender = this.Client.Id,
Receiver = neighborId,
SenderSequenceNr = (AodvSequence)this.CurrentSequence.Clone()
});
}
}
// decrease the neigbor response time (clone key list)
foreach (string key in this.Neighbours.Keys.ToList())
{
this.Neighbours[key] -= 1;
}
// select neighbours where the inactive coutner is zero or less
var inactiveNeighbours = this.Neighbours.Where(n => n.Value <= 0).Select(n => n.Key).ToList();
// if a neighbour was for a period of time inactive (hellotimer * 2)
if (inactiveNeighbours.Any())
{
foreach (var neighbourId in inactiveNeighbours)
{
var routeErrorReceivers = aodvTable.HandleRouteMaintaince(neighbourId);
// enqueue route error messages for sending to route error receivers
routeErrorReceivers.ForEach(
receiver =>
this.SendMessage(
new AodvRouteErrorMessage()
{
Sender = this.Client.Id,
Receiver = receiver,
UnReachableDestination = neighbourId,
UnReachableDestinationSequenceNr = (AodvSequence)this.CurrentSequence.Clone()
}));
// remove the inactive neighbour
this.Neighbours.Remove(neighbourId);
}
}
}
private void IncomingAodvHelloMessageHandler(NetSimMessage message)
{
AodvHelloMessage helloMessage = (AodvHelloMessage)message;
AodvTable aodvTable = (AodvTable)this.Table;
// handle the neighbour lsit update - inactive timer management
this.UpdateNeighbourList(helloMessage.Sender);
// search for a route for hello message sender
AodvTableEntry route = (AodvTableEntry)aodvTable.GetRouteFor(helloMessage.Sender);
// create route for neighbour if not exists
if (route == null)
{
aodvTable.AddRouteEntry(
helloMessage.Sender,
helloMessage.Sender,
1,
(AodvSequence)helloMessage.SenderSequenceNr.Clone());
}
}
private void IncomingAodvRouteRequestMessageHandler(NetSimMessage message)
{
AodvTable aodvTable = (AodvTable)this.Table;
AodvRouteRequestMessage reqMessage = (AodvRouteRequestMessage)message;
// if this node was sender of request - or has already a cached version of request
if (this.IsOwnRequest(reqMessage) || this.HasCachedRequest(reqMessage))
{
// ignore message and proceed
return;
}
// add request to cache
this.AddCachedRequest(reqMessage);
// add reverse routing entry - if route doesn't exist or sequencenr is newer
aodvTable.HandleRequestReverseRouteCaching(reqMessage);
// update request message - increase hopcount and update last hop
reqMessage.LastHop = this.Client.Id;
reqMessage.HopCount += 1;
// check if message destination is current node
if (reqMessage.Receiver.Equals(this.Client.Id))
{
// send back rrep mesage the reverse way
var response = new AodvRouteReplyMessage()
{
Receiver = reqMessage.Sender,
Sender = this.Client.Id,
ReceiverSequenceNr = (AodvSequence)this.CurrentSequence.Clone(),
LastHop = this.Client.Id
};
// enqueue message for sending
this.SendMessage(response);
}
else
{
// Check if route was cached
var searchRoute = aodvTable.SearchCachedRoute(reqMessage);
if (searchRoute != null)
{
// send reply back to requester - send back rrep mesage the reverse way
var response = new AodvRouteReplyMessage()
{
Receiver = reqMessage.Sender,
Sender = searchRoute.Destination,
ReceiverSequenceNr = (AodvSequence)searchRoute.SequenceNr.Clone(),
HopCount = searchRoute.Metric,
LastHop = this.Client.Id
};
// enqueue message for sending
this.SendMessage(response);
}
else
{
// forward message to outgoing messages
this.SendMessage(reqMessage);
}
}
}