diff --git a/weed/topology/configuration.go b/weed/topology/configuration.go
index 2a544ce1d..42c7c140e 100644
--- a/weed/topology/configuration.go
+++ b/weed/topology/configuration.go
@@ -22,7 +22,7 @@ type topology struct {
 type Configuration struct {
 	XMLName     xml.Name `xml:"Configuration"`
 	Topo        topology `xml:"Topology"`
-	ip2location map[string]loc
+	ip2location map[string]loc // this is not used any more. leave it here for later.
 }
 
 func (c *Configuration) String() string {