//process received LSP
public void ReceivePacket(LinkStatePacket lsp)
{
if (_bStatus) //if router is not shut down
{
foreach (Neighbor _neighbour in _lstNeighbors)
{
if (_neighbour.Id.Equals(lsp.Sender)) //update for which tick LSP was received
{
_neighbour.TickForLSP = _nTick;
}
}
lsp.TimeToLive--;
if (lsp.TimeToLive <= 0 || lsp.OriginId.Equals(_strId)) //LSP is lost or source and destination are same
{
return;
}
if (_dicProcessedLSPs.ContainsKey(lsp.OriginId))
{
int seq = _dicProcessedLSPs[lsp.OriginId];
if (seq >= lsp.Sequence) //already processed LSP for source
{
return;
}
}
_dicProcessedLSPs[lsp.OriginId] = lsp.Sequence; //add/update to LSP list
_hsEdges.AddRange(lsp.links); //update set of edges with latest info
ComputeShortestPaths(); //run djikstra algo to compute routing table
SendPacket(lsp); //send to downstream neighbors
}
}
private void SendPacket(LinkStatePacket lsp)
{
string _srSender = lsp.Sender;
lsp.Sender = _strId; //update sender ID to this router
foreach (Neighbor _neighbour in _lstNeighbors)
{
if (!_neighbour.Cost.Equals(LSPConstants.Infinity))
{ //all connected routers for finite cost
if (!_neighbour.Id.Equals(_srSender)) //except the sending one
{
Program._dicRouters[_neighbour.Id].ReceivePacket(lsp);
}
}
}
}
/// <summary>
/// create Link State Packet from router
/// </summary>
public void OriginatePacket()
{
if (_bStatus) //if router is not shut down
{
_nTick++;
_nLspSeq++;
LinkStatePacket _lsp = new LinkStatePacket(_strId, _nLspSeq); //generate LSP
foreach (Neighbor _neighbour in _lstNeighbors)
{
if (_nTick > _neighbour.TickForLSP + 2) //if LSP is heard in two clock ticks then cost is infinity assuming that neighbour is shut down. Remove the edge from graph
{
_neighbour.Cost = LSPConstants.Infinity;
_hsEdges.Remove(new Edge(_strId, _neighbour.Id, 0, ""));
}
else //add LSP to this network details
{
Edge l = new Edge(_strId, _neighbour.Id, _neighbour.Cost, Program._dicRouters[_neighbour.Id]._strNetworkName);
_lsp.addLink(l);
}
}
ComputeShortestPaths(); //run djikstra algo to compute routing table
SendPacket(_lsp); //send to all neighbors
}
}