diff --git a/protos/voltha.proto b/protos/voltha.proto
index fdff7f6..ef6eedf 100644
--- a/protos/voltha.proto
+++ b/protos/voltha.proto
@@ -137,6 +137,15 @@
     string voltha_id = 2;
 }
 
+// Identifies a membership group a Core belongs to
+message Membership {
+    //  Group name
+    string group_name = 1;
+
+    // Unique ID of a container within that group
+    string id = 2;
+}
+
 /*
  * Voltha APIs
  *
@@ -150,6 +159,14 @@
         };
     }
 
+    // Set the membership group of a Voltha Core
+    rpc UpdateMembership(Membership) returns(google.protobuf.Empty) {
+        option (google.api.http) = {
+            post: "/api/v1/membership"
+            body: "*"
+        };
+    }
+
     // Get high level information on the Voltha cluster
     rpc GetVoltha(google.protobuf.Empty) returns(Voltha) {
         option (google.api.http) = {