diff --git a/src/gb/gprs_ns2_internal.h b/src/gb/gprs_ns2_internal.h
index 9b138e5..567e1c5 100644
--- a/src/gb/gprs_ns2_internal.h
+++ b/src/gb/gprs_ns2_internal.h
@@ -182,6 +182,9 @@
 
 	/*! MTU of a NS PDU. This is the lowest MTU of all NSVCs */
 	uint16_t mtu;
+
+	/*! are we implementing the SGSN role? */
+	bool ip_sns_role_sgsn;
 };
 
 /*! Structure representing a single NS-VC */