To simulate the Multiprotocol Label Switching (MPLS) in ns3 has needs to follow numerous steps and it is a method for forwarding packets for numerous protocols using labels. Since MPLS isn’t directly supported in NS3, we can replicate MPLS-like behaviour by using a integration of IP routing and tunnelling mechanisms. NS3’s framework, especially an IP routing that can be expanded to approximate MPLS functionality. MPLS depend on generating Label Switched Paths (LSPs), and in a similar fashion, we can simulate this in NS3 using IP tunneling or predefined routes.
Here’s a general guide on how to simulate MPLS-like behavior using NS3:
Steps to Simulate MPLS-like Behavior in NS3:
- Install NS3: Make sure NS3 is installed.
- Create the Network Topology: Describe a set of nodes signifying routers in the core MPLS network, edge routers (Label Edge Routers), and customer edge devices (CEs). Utilize Point-to-Point (P2P) links to associate the routers, signify the MPLS backbone.
- Simulate Label Switching Paths (LSPs): MPLS forwards packets in terms of labels. Since NS3 doesn’t directly execute MPLS labels, so we can simulate static routes or IP tunneling to signify the pre-determined paths (LSPs). Describe the static routes on intermediate nodes (routers) to forward packets along with particular paths.
- Assign IP Addresses: Each node should have IP addresses configured, as MPLS performs at Layer 3. Make sure that the paths correspond to the network’s structure, permits the simulation of label switching.
- Configure IP Routing or Tunneling: Setting up static routes or utilize IP tunneling to replicate MPLS’s concept of label-switched paths (LSPs) for packet forwarding.
- Set up Applications for Traffic Generation: Utilize UDP or TCP applications to emulate traffic flowing among customer edge devices that will traverse the simulated MPLS network.
Example Simulation of MPLS-like Behavior Using Static Routes
Here’s an instance that shows on how to simulate MPLS-like behaviour using static routes to signify Label Switched Paths (LSPs):
Example: Simulating MPLS-like Behavior in NS3 with Static Routing
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/internet-module.h”
#include “ns3/point-to-point-module.h”
#include “ns3/applications-module.h”
using namespace ns3;
int main (int argc, char *argv[])
{
// Step 1: Create MPLS-like network nodes
NodeContainer ce1, ce2, pRouters, lsr;
ce1.Create (1); // Customer Edge device (CE1)
ce2.Create (1); // Customer Edge device (CE2)
pRouters.Create (3); // Core MPLS network routers (P routers)
lsr.Create (2); // Label Switch Routers (LSRs)
// Step 2: Create point-to-point links between nodes
PointToPointHelper p2p;
p2p.SetDeviceAttribute (“DataRate”, StringValue (“1Gbps”));
p2p.SetChannelAttribute (“Delay”, StringValue (“2ms”));
// Set up links between LSRs, P routers, and CE routers
NetDeviceContainer devices_ce1_lsr1 = p2p.Install (ce1.Get (0), lsr.Get (0));
NetDeviceContainer devices_lsr1_p1 = p2p.Install (lsr.Get (0), pRouters.Get (0));
NetDeviceContainer devices_p1_p2 = p2p.Install (pRouters.Get (0), pRouters.Get (1));
NetDeviceContainer devices_p2_lsr2 = p2p.Install (pRouters.Get (1), lsr.Get (1));
NetDeviceContainer devices_lsr2_ce2 = p2p.Install (lsr.Get (1), ce2.Get (0));
// Step 3: Install Internet stack on all nodes
InternetStackHelper internet;
internet.InstallAll ();
// Step 4: Assign IP addresses to the links
Ipv4AddressHelper ipv4;
ipv4.SetBase (“10.0.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces_ce1_lsr1 = ipv4.Assign (devices_ce1_lsr1);
ipv4.SetBase (“10.0.2.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces_lsr1_p1 = ipv4.Assign (devices_lsr1_p1);
ipv4.SetBase (“10.0.3.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces_p1_p2 = ipv4.Assign (devices_p1_p2);
ipv4.SetBase (“10.0.4.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces_p2_lsr2 = ipv4.Assign (devices_p2_lsr2);
ipv4.SetBase (“10.0.5.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces_lsr2_ce2 = ipv4.Assign (devices_lsr2_ce2);
// Step 5: Set up static routing to simulate MPLS label-switched paths
Ipv4StaticRoutingHelper ipv4RoutingHelper;
Ptr<Ipv4StaticRouting> staticRouting_ce1 = ipv4RoutingHelper.GetStaticRouting (ce1.Get (0)->GetObject<Ipv4> ());
staticRouting_ce1->AddNetworkRouteTo (Ipv4Address (“10.0.5.0”), Ipv4Mask (“255.255.255.0”), Ipv4Address (“10.0.1.2”), 1);
Ptr<Ipv4StaticRouting> staticRouting_lsr1 = ipv4RoutingHelper.GetStaticRouting (lsr.Get (0)->GetObject<Ipv4> ());
staticRouting_lsr1->AddNetworkRouteTo (Ipv4Address (“10.0.5.0”), Ipv4Mask (“255.255.255.0”), Ipv4Address (“10.0.2.2”), 1);
Ptr<Ipv4StaticRouting> staticRouting_p1 = ipv4RoutingHelper.GetStaticRouting (pRouters.Get (0)->GetObject<Ipv4> ());
staticRouting_p1->AddNetworkRouteTo (Ipv4Address (“10.0.5.0”), Ipv4Mask (“255.255.255.0”), Ipv4Address (“10.0.3.2”), 1);
Ptr<Ipv4StaticRouting> staticRouting_p2 = ipv4RoutingHelper.GetStaticRouting (pRouters.Get (1)->GetObject<Ipv4> ());
staticRouting_p2->AddNetworkRouteTo (Ipv4Address (“10.0.5.0”), Ipv4Mask (“255.255.255.0”), Ipv4Address (“10.0.4.2”), 1);
Ptr<Ipv4StaticRouting> staticRouting_lsr2 = ipv4RoutingHelper.GetStaticRouting (lsr.Get (1)->GetObject<Ipv4> ());
staticRouting_lsr2->AddNetworkRouteTo (Ipv4Address (“10.0.1.0”), Ipv4Mask (“255.255.255.0”), Ipv4Address (“10.0.5.2”), 1);
// Step 6: Set up UDP Echo Server on CE2 (customer edge)
UdpEchoServerHelper echoServer (9);
ApplicationContainer serverApps = echoServer.Install (ce2.Get (0));
serverApps.Start (Seconds (1.0));
serverApps.Stop (Seconds (10.0));
// Step 7: Set up UDP Echo Client on CE1 (customer edge)
UdpEchoClientHelper echoClient (interfaces_lsr2_ce2.GetAddress (1), 9);
echoClient.SetAttribute (“MaxPackets”, UintegerValue (1));
echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));
echoClient.SetAttribute (“PacketSize”, UintegerValue (1024));
ApplicationContainer clientApps = echoClient.Install (ce1.Get (0));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
// Step 8: Run the simulation
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
Explanation of the Code:
- Nodes and Links: We generate nodes to signify customer edge routers (CE1, CE2) and core MPLS routers (P1, P2) and label-switch routers (LSR1, LSR2).
- IP Addresses: Each link among nodes is assigned an IP address.
- Static Routes: We utilize static routing to replicate MPLS-like paths (LSPs) by directing traffic along with forecast routes.
- Traffic: A UDP echo client-server application is utilized to replicate traffic flowing from CE1 to CE2, crossing the core network.
Performance Metrics to Measure:
- Throughput: Analyse the total data delivered via the MPLS network.
- Latency/Delay: Estimate the time taken for packets to traverse the label-switched paths.
- Routing Overhead: Investigate control messages interchanged in static routing or, if using dynamic MPLS simulation, the setup and teardown of LSPs.
- Packet Loss: Evaluate on how many packets are successfully delivered vs. lost in transit.
Running the Simulation:
- Build and Run: Execute the following commands in NS3 directory:
./waf configure
./waf build
./waf –run <your-script-name>
Extending the Simulation:
- Integrating Dynamic Label Switching: we can expand the static routing sample to dynamically replicate label switching by executing or using modules that approximate MPLS features.
- Using NS3-DCE: We can utilize NS3-DCE to incorporate real MPLS protocol stacks such as Quagga or FRRouting with NS3. This permits more realistic MPLS behaviour simulation.
From the demonstration we clearly learned the novel concepts that were sophisticated to simulate the Multiprotocol Label Switching in ns3 that outperforms the better results to manage the network packet transmission. We plan to deliver more information regarding the Multiprotocol Label Switching.
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