diff --git a/api/envoy/config/cluster/v3/filter.proto b/api/envoy/config/cluster/v3/filter.proto
index 74f4a1137dab6..7d11b87bcd5d5 100644
--- a/api/envoy/config/cluster/v3/filter.proto
+++ b/api/envoy/config/cluster/v3/filter.proto
@@ -20,7 +20,8 @@ message Filter {
   option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.cluster.Filter";
 
   // The name of the filter to instantiate. The name must match a
-  // :ref:`supported filter <config_network_filters>`.
+  // supported upstream filter. Note that Envoy's :ref:`downstream network
+  // filters <config_network_filters>` are not valid upstream filters.
   string name = 1 [(validate.rules).string = {min_len: 1}];
 
   // Filter specific configuration which depends on the filter being
diff --git a/api/envoy/config/cluster/v4alpha/filter.proto b/api/envoy/config/cluster/v4alpha/filter.proto
index 5a4a4facbd81e..d478fd34f1c79 100644
--- a/api/envoy/config/cluster/v4alpha/filter.proto
+++ b/api/envoy/config/cluster/v4alpha/filter.proto
@@ -20,7 +20,8 @@ message Filter {
   option (udpa.annotations.versioning).previous_message_type = "envoy.config.cluster.v3.Filter";
 
   // The name of the filter to instantiate. The name must match a
-  // :ref:`supported filter <config_network_filters>`.
+  // supported upstream filter. Note that Envoy's :ref:`downstream network
+  // filters <config_network_filters>` are not valid upstream filters.
   string name = 1 [(validate.rules).string = {min_len: 1}];
 
   // Filter specific configuration which depends on the filter being
diff --git a/generated_api_shadow/envoy/config/cluster/v3/filter.proto b/generated_api_shadow/envoy/config/cluster/v3/filter.proto
index 74f4a1137dab6..7d11b87bcd5d5 100644
--- a/generated_api_shadow/envoy/config/cluster/v3/filter.proto
+++ b/generated_api_shadow/envoy/config/cluster/v3/filter.proto
@@ -20,7 +20,8 @@ message Filter {
   option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.cluster.Filter";
 
   // The name of the filter to instantiate. The name must match a
-  // :ref:`supported filter <config_network_filters>`.
+  // supported upstream filter. Note that Envoy's :ref:`downstream network
+  // filters <config_network_filters>` are not valid upstream filters.
   string name = 1 [(validate.rules).string = {min_len: 1}];
 
   // Filter specific configuration which depends on the filter being
diff --git a/generated_api_shadow/envoy/config/cluster/v4alpha/filter.proto b/generated_api_shadow/envoy/config/cluster/v4alpha/filter.proto
index 5a4a4facbd81e..d478fd34f1c79 100644
--- a/generated_api_shadow/envoy/config/cluster/v4alpha/filter.proto
+++ b/generated_api_shadow/envoy/config/cluster/v4alpha/filter.proto
@@ -20,7 +20,8 @@ message Filter {
   option (udpa.annotations.versioning).previous_message_type = "envoy.config.cluster.v3.Filter";
 
   // The name of the filter to instantiate. The name must match a
-  // :ref:`supported filter <config_network_filters>`.
+  // supported upstream filter. Note that Envoy's :ref:`downstream network
+  // filters <config_network_filters>` are not valid upstream filters.
   string name = 1 [(validate.rules).string = {min_len: 1}];
 
   // Filter specific configuration which depends on the filter being