BUG:TcpFlow

configuration_examples/simulation_examples/basic_simulation.yml

@@ -5,13 +5,11 @@ flows:
     sender_id: "sender1"
     receiver_id: "receiver1"
     packet_size: 1024
-    packet_interval: 100
     number_of_packets: 10000
   flow2:
     sender_id: "sender2"
     receiver_id: "receiver2"
     packet_size: 1024
-    packet_interval: 100
     number_of_packets: 10000
 
 algorithm: basic

configuration_examples/simulation_examples/incast_simulation.yml

@@ -4,31 +4,26 @@ flows:
     sender_id: sender0
     receiver_id: receiver0
     packet_size: 1500
-    packet_interval: 500
     number_of_packets: 100
   flow1:
     sender_id: sender1
     receiver_id: receiver0
     packet_size: 1500
-    packet_interval: 500
     number_of_packets: 100
   flow2:
     sender_id: sender2
     receiver_id: receiver0
     packet_size: 1500
-    packet_interval: 500
     number_of_packets: 100
   flow3:
     sender_id: sender3
     receiver_id: receiver0
     packet_size: 1500
-    packet_interval: 500
     number_of_packets: 100
   flow4:
     sender_id: sender4
     receiver_id: receiver0
     packet_size: 1500
-    packet_interval: 500
     number_of_packets: 100
 algorithm: tcp
 simulation_time: 50000

configuration_examples/simulation_examples/tcp_simulation.yml

@@ -5,13 +5,11 @@ flows:
     sender_id: "sender1"
     receiver_id: "receiver1"
     packet_size: 64
-    packet_interval: 600
     number_of_packets: 100
   flow2:
     sender_id: "sender2"
     receiver_id: "receiver2"
     packet_size: 128
-    packet_interval: 600
     number_of_packets: 100
 
 algorithm: tcp

source/flow/i_flow.hpp

@@ -7,15 +7,13 @@ namespace sim {
 
 class IFlow : public Identifiable {
 public:
+    // Start sending packets
     virtual void start() = 0;
-    // Adds new packet to sending queue
-    // This packet will be send at some time in future (depends on concrete
-    // flow) Used in event Generate
-    virtual TimeNs create_new_data_packet() = 0;
 
     // Update the internal state according to some congestion control algorithm
     // Calls when data available for sending on corresponding device
     virtual void update(Packet packet, DeviceType type) = 0;
+
     virtual std::shared_ptr<IHost> get_sender() const = 0;
     virtual std::shared_ptr<IHost> get_receiver() const = 0;
 };

source/flow/tcp/basic/basic_cc.cpp

@@ -4,9 +4,8 @@
 
 namespace sim {
 
-bool BasicCC::on_ack(TimeNs rtt, bool ecn_flag) {
-    (void)rtt;
-    (void)ecn_flag;
+bool BasicCC::on_ack([[maybe_unused]] TimeNs rtt, [[maybe_unused]] TimeNs avg_rtt,
+                     [[maybe_unused]] bool ecn_flag) {
     return false;
 }
 

source/flow/tcp/basic/basic_cc.hpp

@@ -5,7 +5,7 @@
 namespace sim {
 class BasicCC : public ITcpCC {
 public:
-    bool on_ack(TimeNs rtt, bool ecn_flag) final;
+    bool on_ack(TimeNs rtt, TimeNs avg_rtt, bool ecn_flag) final;
     TimeNs get_pacing_delay() const final;
     double get_cwnd() const final;
     std::string to_string() const final;

source/flow/tcp/i_tcp_cc.hpp

@@ -8,7 +8,7 @@ class ITcpCC {
 public:
     // Callback that triggers every time ACK receives on sender
     // returns true if congestion detected; false otherwice
-    virtual bool on_ack(TimeNs rtt, bool ecn_flag) = 0;
+    virtual bool on_ack(TimeNs rtt, TimeNs avg_rtt, bool ecn_flag) = 0;
     virtual TimeNs get_pacing_delay() const = 0;
     virtual double get_cwnd() const = 0;
     virtual std::string to_string() const = 0;

source/flow/tcp/tahoe/tcp_tahoe_cc.cpp

@@ -2,22 +2,33 @@
 
 #include <spdlog/fmt/fmt.h>
 
+#include "scheduler.hpp"
+
 namespace sim {
 TcpTahoeCC::TcpTahoeCC(TimeNs a_delay_threshold, double a_sstresh)
     : m_delay_threshold(a_delay_threshold),
       m_ssthresh(a_sstresh),
-      m_cwnd(1.0) {}
+      m_cwnd(1.0),
+      m_last_congestion_detected(0) {}
 
-bool TcpTahoeCC::on_ack(TimeNs rtt, bool ecn_flag) {
-    if (ecn_flag || rtt > m_delay_threshold) {
+bool TcpTahoeCC::on_ack([[maybe_unused]] TimeNs rtt, TimeNs avg_rtt,
+                        bool ecn_flag) {
+    Time current_time = Scheduler::get_instance().get_current_time();
+    if (ecn_flag || avg_rtt > m_delay_threshold) {
         // trigger_congestion
-        m_ssthresh = m_cwnd / 2;
-        m_cwnd = 1.;
+        if (current_time > m_last_congestion_detected + avg_rtt) {
+            // To avoid too frequent cwnd and sstresh decreases
+            m_last_congestion_detected = current_time;
+            m_ssthresh = m_cwnd / 2;
+            m_cwnd = 1.;
+        }
         return true;
     }
     if (m_cwnd < m_ssthresh) {
+        // Slow start
         m_cwnd++;
     } else {
+        // Congestion avoidance
         m_cwnd += 1 / m_cwnd;
     }
     return false;
@@ -32,4 +43,4 @@ std::string TcpTahoeCC::to_string() const {
                        m_delay_threshold.value(), m_cwnd, m_ssthresh);
 }
 
-}  // namespace sim
+}  // namespace sim

source/flow/tcp/tahoe/tcp_tahoe_cc.hpp

@@ -7,7 +7,7 @@ class TcpTahoeCC : public ITcpCC {
     TcpTahoeCC(TimeNs a_delay_threshold = TimeNs(4000), double a_ssthresh = 8);
     ~TcpTahoeCC() = default;
 
-    bool on_ack(TimeNs rtt, bool ecn_flag) final;
+    bool on_ack(TimeNs rtt, TimeNs avg_rtt, bool ecn_flag) final;
     TimeNs get_pacing_delay() const final;
     double get_cwnd() const final;
     std::string to_string() const final;
@@ -17,5 +17,6 @@ class TcpTahoeCC : public ITcpCC {
 
     double m_ssthresh;  // Slow start threshold
     double m_cwnd;      // Congestion window
+    TimeNs m_last_congestion_detected;
 };
 }  // namespace sim