diff --git a/call/rtp_config.h b/call/rtp_config.h
index 96fe15fbb1..8f8d03a3a8 100644
--- a/call/rtp_config.h
+++ b/call/rtp_config.h
@@ -22,6 +22,7 @@ namespace webrtc {
 struct RtpPayloadState {
   int16_t picture_id = -1;
   uint8_t tl0_pic_idx = 0;
+  int64_t shared_frame_id = 0;
 };
 // Settings for NACK, see RFC 4585 for details.
 struct NackConfig {
diff --git a/call/rtp_video_sender.cc b/call/rtp_video_sender.cc
index a7a57705f0..8c627b498b 100644
--- a/call/rtp_video_sender.cc
+++ b/call/rtp_video_sender.cc
@@ -10,6 +10,7 @@
 
 #include "call/rtp_video_sender.h"
 
+#include <algorithm>
 #include <memory>
 #include <string>
 #include <utility>
@@ -206,6 +207,7 @@ RtpVideoSender::RtpVideoSender(
     auto it = states.find(ssrc);
     if (it != states.end()) {
       state = &it->second;
+      shared_frame_id_ = std::max(shared_frame_id_, state->shared_frame_id);
     }
     params_.push_back(RtpPayloadParams(ssrc, state));
   }
@@ -541,6 +543,7 @@ std::map<uint32_t, RtpPayloadState> RtpVideoSender::GetRtpPayloadStates()
   std::map<uint32_t, RtpPayloadState> payload_states;
   for (const auto& param : params_) {
     payload_states[param.ssrc()] = param.state();
+    payload_states[param.ssrc()].shared_frame_id = shared_frame_id_;
   }
   return payload_states;
 }
diff --git a/call/rtp_video_sender.h b/call/rtp_video_sender.h
index 02feff27d9..1735dc751a 100644
--- a/call/rtp_video_sender.h
+++ b/call/rtp_video_sender.h
@@ -118,6 +118,11 @@ class RtpVideoSender : public RtpVideoSenderInterface {
   const RtpConfig rtp_config_;
   RtpTransportControllerSendInterface* const transport_;
 
+  // When using the generic descriptor we want all simulcast streams to share
+  // one frame id space (so that the SFU can switch stream without having to
+  // rewrite the frame id), therefore |shared_frame_id| has to live in a place
+  // where we are aware of all the different streams.
+  int64_t shared_frame_id_ = 0;
   std::vector<RtpPayloadParams> params_ RTC_GUARDED_BY(crit_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(RtpVideoSender);
diff --git a/call/rtp_video_sender_unittest.cc b/call/rtp_video_sender_unittest.cc
index 45f8149bba..b819e696d9 100644
--- a/call/rtp_video_sender_unittest.cc
+++ b/call/rtp_video_sender_unittest.cc
@@ -270,12 +270,16 @@ TEST(RtpVideoSenderTest, CreateWithNoPreviousStates) {
 }
 
 TEST(RtpVideoSenderTest, CreateWithPreviousStates) {
+  const int64_t kState1SharedFrameId = 123;
+  const int64_t kState2SharedFrameId = 234;
   RtpPayloadState state1;
   state1.picture_id = kInitialPictureId1;
   state1.tl0_pic_idx = kInitialTl0PicIdx1;
+  state1.shared_frame_id = kState1SharedFrameId;
   RtpPayloadState state2;
   state2.picture_id = kInitialPictureId2;
   state2.tl0_pic_idx = kInitialTl0PicIdx2;
+  state2.shared_frame_id = kState2SharedFrameId;
   std::map<uint32_t, RtpPayloadState> states = {{kSsrc1, state1},
                                                 {kSsrc2, state2}};
 
@@ -289,5 +293,7 @@ TEST(RtpVideoSenderTest, CreateWithPreviousStates) {
   EXPECT_EQ(kInitialTl0PicIdx1, initial_states[kSsrc1].tl0_pic_idx);
   EXPECT_EQ(kInitialPictureId2, initial_states[kSsrc2].picture_id);
   EXPECT_EQ(kInitialTl0PicIdx2, initial_states[kSsrc2].tl0_pic_idx);
+  EXPECT_EQ(kState2SharedFrameId, initial_states[kSsrc1].shared_frame_id);
+  EXPECT_EQ(kState2SharedFrameId, initial_states[kSsrc2].shared_frame_id);
 }
 }  // namespace webrtc