diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index 6f5e348..e6500f3 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -239,6 +239,11 @@
       send_algorithm_->SetInitialCongestionWindowInPackets(50);
     }
   }
+  if (GetQuicReloadableFlag(quic_use_ip_bandwidth_module) &&
+      config.HasClientRequestedIndependentOption(kBWS5, perspective)) {
+    initial_congestion_window_ = 10;
+    send_algorithm_->SetInitialCongestionWindowInPackets(10);
+  }
 
   using_pacing_ = !GetQuicFlag(FLAGS_quic_disable_pacing_for_perf_tests);
 
diff --git a/quic/core/quic_sent_packet_manager_test.cc b/quic/core/quic_sent_packet_manager_test.cc
index 7e8e3e7..5322ffb 100644
--- a/quic/core/quic_sent_packet_manager_test.cc
+++ b/quic/core/quic_sent_packet_manager_test.cc
@@ -3313,6 +3313,20 @@
             manager_.GetRetransmissionTime());
 }
 
+TEST_F(QuicSentPacketManagerTest, IW10ForUpAndDown) {
+  SetQuicReloadableFlag(quic_use_ip_bandwidth_module, true);
+  QuicConfig config;
+  QuicTagVector options;
+  options.push_back(kBWS5);
+  QuicConfigPeer::SetReceivedConnectionOptions(&config, options);
+  EXPECT_CALL(*send_algorithm_, SetFromConfig(_, _));
+  EXPECT_CALL(*send_algorithm_, SetInitialCongestionWindowInPackets(10));
+  EXPECT_CALL(*network_change_visitor_, OnCongestionChange());
+  manager_.SetFromConfig(config);
+
+  EXPECT_EQ(10u, manager_.initial_congestion_window());
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace quic