diff --git a/google/cloud/networkmanagement/v1/trace.proto b/google/cloud/networkmanagement/v1/trace.proto
index eeaba9cb7c..78794b6348 100644
--- a/google/cloud/networkmanagement/v1/trace.proto
+++ b/google/cloud/networkmanagement/v1/trace.proto
@@ -682,7 +682,9 @@ message RouteInfo {
 
   // Region of the route. DYNAMIC, PEERING_DYNAMIC, POLICY_BASED and ADVERTISED
   // routes only. If set for POLICY_BASED route, this is a region of VLAN
-  // attachments for Cloud Interconnect the route applies to.
+  // attachments for Cloud Interconnect the route applies to. If set to "all"
+  // for POLICY_BASED route, the route applies to VLAN attachments of Cloud
+  // Interconnect in all regions.
   string region = 19;
 
   // Destination IP range of the route.
diff --git a/google/cloud/networkmanagement/v1beta1/trace.proto b/google/cloud/networkmanagement/v1beta1/trace.proto
index bd1feefbda..8c0d21d892 100644
--- a/google/cloud/networkmanagement/v1beta1/trace.proto
+++ b/google/cloud/networkmanagement/v1beta1/trace.proto
@@ -686,7 +686,9 @@ message RouteInfo {
 
   // Region of the route. DYNAMIC, PEERING_DYNAMIC, POLICY_BASED and ADVERTISED
   // routes only. If set for POLICY_BASED route, this is a region of VLAN
-  // attachments for Cloud Interconnect the route applies to.
+  // attachments for Cloud Interconnect the route applies to. If set to "all"
+  // for POLICY_BASED route, the route applies to VLAN attachments of Cloud
+  // Interconnect in all regions.
   string region = 19;
 
   // Destination IP range of the route.