diff --git a/quic/core/quic_framer.cc b/quic/core/quic_framer.cc
index 7e34b3b..328e453 100644
--- a/quic/core/quic_framer.cc
+++ b/quic/core/quic_framer.cc
@@ -2624,6 +2624,7 @@
 bool QuicFramer::ProcessAndValidateIetfConnectionIdLength(
     QuicDataReader* reader,
     ParsedQuicVersion version,
+    Perspective perspective,
     bool should_update_expected_server_connection_id_length,
     uint8_t* expected_server_connection_id_length,
     uint8_t* destination_connection_id_length,
@@ -2639,17 +2640,20 @@
   if (dcil != 0) {
     dcil += kConnectionIdLengthAdjustment;
   }
-  if (should_update_expected_server_connection_id_length &&
-      *expected_server_connection_id_length != dcil) {
-    QUIC_DVLOG(1) << "Updating expected_server_connection_id_length: "
-                  << static_cast<int>(*expected_server_connection_id_length)
-                  << " -> " << static_cast<int>(dcil);
-    *expected_server_connection_id_length = dcil;
-  }
   uint8_t scil = connection_id_lengths_byte & kSourceConnectionIdLengthMask;
   if (scil != 0) {
     scil += kConnectionIdLengthAdjustment;
   }
+  if (should_update_expected_server_connection_id_length) {
+    uint8_t server_connection_id_length =
+        perspective == Perspective::IS_SERVER ? dcil : scil;
+    if (*expected_server_connection_id_length != server_connection_id_length) {
+      QUIC_DVLOG(1) << "Updating expected_server_connection_id_length: "
+                    << static_cast<int>(*expected_server_connection_id_length)
+                    << " -> " << static_cast<int>(server_connection_id_length);
+      *expected_server_connection_id_length = server_connection_id_length;
+    }
+  }
   if (!should_update_expected_server_connection_id_length &&
       (dcil != *destination_connection_id_length ||
        scil != *source_connection_id_length) &&
@@ -2683,7 +2687,7 @@
           : 0;
   if (header->form == IETF_QUIC_LONG_HEADER_PACKET) {
     if (!ProcessAndValidateIetfConnectionIdLength(
-            reader, header->version,
+            reader, header->version, perspective_,
             should_update_expected_server_connection_id_length_,
             &expected_server_connection_id_length_,
             &destination_connection_id_length, &source_connection_id_length,
@@ -6099,6 +6103,7 @@
     uint8_t unused_expected_server_connection_id_length = 0;
     if (!ProcessAndValidateIetfConnectionIdLength(
             &reader, ParseQuicVersionLabel(*version_label),
+            Perspective::IS_SERVER,
             /*should_update_expected_server_connection_id_length=*/true,
             &unused_expected_server_connection_id_length,
             destination_connection_id_length,
@@ -6247,7 +6252,7 @@
   uint8_t expected_server_connection_id_length = 0,
           destination_connection_id_length = 0, source_connection_id_length = 0;
   if (!ProcessAndValidateIetfConnectionIdLength(
-          &reader, UnsupportedQuicVersion(),
+          &reader, UnsupportedQuicVersion(), Perspective::IS_CLIENT,
           /*should_update_expected_server_connection_id_length=*/true,
           &expected_server_connection_id_length,
           &destination_connection_id_length, &source_connection_id_length,
diff --git a/quic/core/quic_framer.h b/quic/core/quic_framer.h
index 11d48bb..e6eecf1 100644
--- a/quic/core/quic_framer.h
+++ b/quic/core/quic_framer.h
@@ -714,10 +714,15 @@
                                   QuicVersionLabel* version_label);
 
   // Validates and updates |destination_connection_id_length| and
-  // |source_connection_id_length|.
+  // |source_connection_id_length|. When
+  // |should_update_expected_server_connection_id_length| is true, length
+  // validation is disabled and |expected_server_connection_id_length| is set
+  // to the appropriate length.
+  // TODO(b/133873272) refactor this method.
   static bool ProcessAndValidateIetfConnectionIdLength(
       QuicDataReader* reader,
       ParsedQuicVersion version,
+      Perspective perspective,
       bool should_update_expected_server_connection_id_length,
       uint8_t* expected_server_connection_id_length,
       uint8_t* destination_connection_id_length,
diff --git a/quic/core/quic_framer_test.cc b/quic/core/quic_framer_test.cc
index 13e4482..22ffe4f 100644
--- a/quic/core/quic_framer_test.cc
+++ b/quic/core/quic_framer_test.cc
@@ -13840,6 +13840,82 @@
   }
 }
 
+TEST_P(QuicFramerTest, ProcessAndValidateIetfConnectionIdLengthClient) {
+  if (framer_.transport_version() <= QUIC_VERSION_43) {
+    // This test requires an IETF long header.
+    return;
+  }
+  char connection_id_lengths = 0x05;
+  QuicDataReader reader(&connection_id_lengths, 1);
+
+  bool should_update_expected_server_connection_id_length = false;
+  uint8_t expected_server_connection_id_length = 8;
+  uint8_t destination_connection_id_length = 0;
+  uint8_t source_connection_id_length = 8;
+  std::string detailed_error = "";
+
+  EXPECT_TRUE(QuicFramerPeer::ProcessAndValidateIetfConnectionIdLength(
+      &reader, framer_.version(), Perspective::IS_CLIENT,
+      should_update_expected_server_connection_id_length,
+      &expected_server_connection_id_length, &destination_connection_id_length,
+      &source_connection_id_length, &detailed_error));
+  EXPECT_EQ(8, expected_server_connection_id_length);
+  EXPECT_EQ(0, destination_connection_id_length);
+  EXPECT_EQ(8, source_connection_id_length);
+  EXPECT_EQ("", detailed_error);
+
+  QuicDataReader reader2(&connection_id_lengths, 1);
+  should_update_expected_server_connection_id_length = true;
+  expected_server_connection_id_length = 33;
+  EXPECT_TRUE(QuicFramerPeer::ProcessAndValidateIetfConnectionIdLength(
+      &reader2, framer_.version(), Perspective::IS_CLIENT,
+      should_update_expected_server_connection_id_length,
+      &expected_server_connection_id_length, &destination_connection_id_length,
+      &source_connection_id_length, &detailed_error));
+  EXPECT_EQ(8, expected_server_connection_id_length);
+  EXPECT_EQ(0, destination_connection_id_length);
+  EXPECT_EQ(8, source_connection_id_length);
+  EXPECT_EQ("", detailed_error);
+}
+
+TEST_P(QuicFramerTest, ProcessAndValidateIetfConnectionIdLengthServer) {
+  if (framer_.transport_version() <= QUIC_VERSION_43) {
+    // This test requires an IETF long header.
+    return;
+  }
+  char connection_id_lengths = 0x50;
+  QuicDataReader reader(&connection_id_lengths, 1);
+
+  bool should_update_expected_server_connection_id_length = false;
+  uint8_t expected_server_connection_id_length = 8;
+  uint8_t destination_connection_id_length = 8;
+  uint8_t source_connection_id_length = 0;
+  std::string detailed_error = "";
+
+  EXPECT_TRUE(QuicFramerPeer::ProcessAndValidateIetfConnectionIdLength(
+      &reader, framer_.version(), Perspective::IS_SERVER,
+      should_update_expected_server_connection_id_length,
+      &expected_server_connection_id_length, &destination_connection_id_length,
+      &source_connection_id_length, &detailed_error));
+  EXPECT_EQ(8, expected_server_connection_id_length);
+  EXPECT_EQ(8, destination_connection_id_length);
+  EXPECT_EQ(0, source_connection_id_length);
+  EXPECT_EQ("", detailed_error);
+
+  QuicDataReader reader2(&connection_id_lengths, 1);
+  should_update_expected_server_connection_id_length = true;
+  expected_server_connection_id_length = 33;
+  EXPECT_TRUE(QuicFramerPeer::ProcessAndValidateIetfConnectionIdLength(
+      &reader2, framer_.version(), Perspective::IS_SERVER,
+      should_update_expected_server_connection_id_length,
+      &expected_server_connection_id_length, &destination_connection_id_length,
+      &source_connection_id_length, &detailed_error));
+  EXPECT_EQ(8, expected_server_connection_id_length);
+  EXPECT_EQ(8, destination_connection_id_length);
+  EXPECT_EQ(0, source_connection_id_length);
+  EXPECT_EQ("", detailed_error);
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace quic
diff --git a/quic/test_tools/quic_framer_peer.cc b/quic/test_tools/quic_framer_peer.cc
index 6eedd60..94493c3 100644
--- a/quic/test_tools/quic_framer_peer.cc
+++ b/quic/test_tools/quic_framer_peer.cc
@@ -351,5 +351,22 @@
   return framer->largest_decrypted_packet_numbers_[packet_number_space];
 }
 
+// static
+bool QuicFramerPeer::ProcessAndValidateIetfConnectionIdLength(
+    QuicDataReader* reader,
+    ParsedQuicVersion version,
+    Perspective perspective,
+    bool should_update_expected_server_connection_id_length,
+    uint8_t* expected_server_connection_id_length,
+    uint8_t* destination_connection_id_length,
+    uint8_t* source_connection_id_length,
+    std::string* detailed_error) {
+  return QuicFramer::ProcessAndValidateIetfConnectionIdLength(
+      reader, version, perspective,
+      should_update_expected_server_connection_id_length,
+      expected_server_connection_id_length, destination_connection_id_length,
+      source_connection_id_length, detailed_error);
+}
+
 }  // namespace test
 }  // namespace quic
diff --git a/quic/test_tools/quic_framer_peer.h b/quic/test_tools/quic_framer_peer.h
index 0b17c19..7a09a92 100644
--- a/quic/test_tools/quic_framer_peer.h
+++ b/quic/test_tools/quic_framer_peer.h
@@ -166,6 +166,16 @@
   static QuicPacketNumber GetLargestDecryptedPacketNumber(
       QuicFramer* framer,
       PacketNumberSpace packet_number_space);
+
+  static bool ProcessAndValidateIetfConnectionIdLength(
+      QuicDataReader* reader,
+      ParsedQuicVersion version,
+      Perspective perspective,
+      bool should_update_expected_server_connection_id_length,
+      uint8_t* expected_server_connection_id_length,
+      uint8_t* destination_connection_id_length,
+      uint8_t* source_connection_id_length,
+      std::string* detailed_error);
 };
 
 }  // namespace test