diff --git a/plugins/ipam/dhcp/daemon.go b/plugins/ipam/dhcp/daemon.go
index 962264d4..f1bceeab 100644
--- a/plugins/ipam/dhcp/daemon.go
+++ b/plugins/ipam/dhcp/daemon.go
@@ -33,8 +33,6 @@ import (
 	"github.com/coreos/go-systemd/v22/activation"
 )
 
-const listenFdsStart = 3
-
 var errNoMoreTries = errors.New("no more tries")
 
 type DHCP struct {
@@ -54,8 +52,15 @@ func newDHCP(clientTimeout, clientResendMax time.Duration) *DHCP {
 	}
 }
 
+// TODO: current client ID is too long. At least the container ID should not be used directly.
+// A seperate issue is necessary to ensure no breaking change is affecting other users.
 func generateClientID(containerID string, netName string, ifName string) string {
-	return containerID + "/" + netName + "/" + ifName
+	clientID := containerID + "/" + netName + "/" + ifName
+	// defined in RFC 2132, length size can not be larger than 1 octet. So we truncate 254 to make everyone happy.
+	if len(clientID) > 254 {
+		clientID = clientID[0:254]
+	}
+	return clientID
 }
 
 // Allocate acquires an IP from a DHCP server for a specified container.