diff --git a/src/bts.h b/src/bts.h
index e845995..3d74b75 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -133,6 +133,7 @@
 	uint32_t alloc_algorithm_curst; /* options to customize algorithm */
 	uint8_t force_two_phase;
 	uint8_t alpha, gamma;
+	uint32_t dl_tbf_idle_msec; /* hold time for idle DL TBFs */
 
 	/* TBF handling, make private or move into TBFController */
 	/* list of uplink TBFs */
diff --git a/src/pcu_utils.h b/src/pcu_utils.h
new file mode 100644
index 0000000..84c545b
--- /dev/null
+++ b/src/pcu_utils.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2015 by Sysmocom s.f.m.c. GmbH
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+inline int msecs_to_frames(int msecs) {
+	return (msecs * (1024 * 1000 / 4615)) / 1024;
+}
diff --git a/src/pcu_vty.c b/src/pcu_vty.c
index 578a10b..9b597ad 100644
--- a/src/pcu_vty.c
+++ b/src/pcu_vty.c
@@ -105,6 +105,9 @@
 		vty_out(vty, " two-phase-access%s", VTY_NEWLINE);
 	vty_out(vty, " alpha %d%s", bts->alpha, VTY_NEWLINE);
 	vty_out(vty, " gamma %d%s", bts->gamma * 2, VTY_NEWLINE);
+	if (bts->dl_tbf_idle_msec)
+		vty_out(vty, " dl-tbf-idle-time %d%s", bts->dl_tbf_idle_msec,
+			VTY_NEWLINE);
 
 	return CMD_SUCCESS;
 }
@@ -287,6 +290,31 @@
 	return CMD_SUCCESS;
 }
 
+#define IDLE_TIME_STR "keep an idle DL TBF alive for the time given\n"
+DEFUN(cfg_pcu_dl_tbf_idle_time,
+      cfg_pcu_dl_tbf_idle_time_cmd,
+      "dl-tbf-idle-time <1-5000>",
+      IDLE_TIME_STR "idle time in msec")
+{
+	struct gprs_rlcmac_bts *bts = bts_main_data();
+
+	bts->dl_tbf_idle_msec = atoi(argv[0]);
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_pcu_no_dl_tbf_idle_time,
+      cfg_pcu_no_dl_tbf_idle_time_cmd,
+      "no dl-tbf-idle-time",
+      NO_STR IDLE_TIME_STR)
+{
+	struct gprs_rlcmac_bts *bts = bts_main_data();
+
+	bts->dl_tbf_idle_msec = 0;
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(show_tbf,
       show_tbf_cmd,
       "show tbf all",
@@ -343,6 +371,8 @@
 	install_element(PCU_NODE, &cfg_pcu_fc_interval_cmd);
 	install_element(PCU_NODE, &cfg_pcu_alpha_cmd);
 	install_element(PCU_NODE, &cfg_pcu_gamma_cmd);
+	install_element(PCU_NODE, &cfg_pcu_dl_tbf_idle_time_cmd);
+	install_element(PCU_NODE, &cfg_pcu_no_dl_tbf_idle_time_cmd);
 	install_element(PCU_NODE, &ournode_end_cmd);
 
 	install_element_ve(&show_bts_stats_cmd);
diff --git a/src/tbf.cpp b/src/tbf.cpp
index 56804c3..2c7bd94 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -471,6 +471,7 @@
 	tbf->bts->tbf_dl_created();
 
 	tbf->m_last_dl_poll_fn = -1;
+	tbf->m_last_dl_drained_fn = -1;
 
 	gettimeofday(&tbf->m_bw.dl_bw_tv, NULL);
 	gettimeofday(&tbf->m_bw.dl_loss_tv, NULL);
diff --git a/src/tbf.h b/src/tbf.h
index ca5fedf..17ba980 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -326,6 +326,8 @@
 	bool need_control_ts() const;
 	bool have_data() const;
 	int frames_since_last_poll(unsigned fn) const;
+	int frames_since_last_drain(unsigned fn) const;
+	bool keep_open(unsigned fn) const;
 
 	bool is_control_ts(uint8_t ts) const {
 		return ts == control_ts;
@@ -344,6 +346,7 @@
 	uint8_t m_wait_confirm; /* wait for CCCH IMM.ASS cnf */
 	bool m_dl_ack_requested;
 	int32_t m_last_dl_poll_fn;
+	int32_t m_last_dl_drained_fn;
 
 	struct {
 		struct timeval dl_bw_tv; /* timestamp for dl bw calculation */
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 9baa1cd..65b164e 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -27,6 +27,8 @@
 #include <gprs_bssgp_pcu.h>
 #include <decoding.h>
 
+#include "pcu_utils.h"
+
 extern "C" {
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/talloc.h>
@@ -74,6 +76,8 @@
 	} else if (!have_data()) {
 		m_llc.put_frame(data, len);
 		bts->llc_frame_sched();
+		/* it is no longer drained */
+		m_last_dl_drained_fn = -1;
 		tbf_update_ms_class(this, ms_class);
 	} else {
 		/* the TBF exists, so we must write it in the queue
@@ -354,14 +358,19 @@
 			 * space-1 octets */
 			m_llc.put_dummy_frame(space - 1);
 
+			/* The data just drained, store the current fn */
+			if (m_last_dl_drained_fn < 0)
+				m_last_dl_drained_fn = fn;
+
 			/* It is not clear, when the next real data will
 			 * arrive, so request a DL ack/nack now */
 			request_dl_ack();
 
 			LOGP(DRLCMACDL, LOGL_DEBUG,
 				"-- Empty chunk, "
-				"added LLC dummy command of size %d\n",
-				m_llc.frame_length());
+				"added LLC dummy command of size %d, "
+				"drained_since=%d\n",
+				m_llc.frame_length(), frames_since_last_drain(fn));
 		}
 
 		chunk = m_llc.chunk_size();
@@ -380,7 +389,8 @@
 			break;
 		}
 		/* if FINAL chunk would fit precisely in space left */
-		if (chunk == space && llist_empty(&m_llc.queue)) {
+		if (chunk == space && llist_empty(&m_llc.queue) && !keep_open(fn))
+		{
 			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d "
 				"would exactly fit into space (%d): because "
 				"this is a final block, we don't add length "
@@ -424,6 +434,7 @@
 			/* return data block as message */
 			break;
 		}
+
 		LOGP(DRLCMACDL, LOGL_DEBUG, "-- Chunk with length %d is less "
 			"than remaining space (%d): add length header to "
 			"to delimit LLC frame\n", chunk, space);
@@ -456,17 +467,19 @@
 			m_llc.put_frame(msg->data, msg->len);
 			bts->llc_frame_sched();
 			msgb_free(msg);
+			m_last_dl_drained_fn = -1;
 		}
 		/* if we have more data and we have space left */
-		if (space > 0 && m_llc.frame_length()) {
+		if (space > 0 && (m_llc.frame_length() || keep_open(fn))) {
 			li->m = 1; /* we indicate more frames to follow */
 			continue;
 		}
 		/* if we don't have more LLC frames */
-		if (!m_llc.frame_length()) {
+		if (!m_llc.frame_length() && !keep_open(fn)) {
 			LOGP(DRLCMACDL, LOGL_DEBUG, "-- Final block, so we "
 				"done.\n");
 			li->e = 1; /* we cannot extend */
+
 			rh->fbi = 1; /* we indicate final block */
 			request_dl_ack();
 			set_state(GPRS_RLCMAC_FINISHED);
@@ -771,3 +784,26 @@
 		return wrapped - 2715648;
 }
 
+int gprs_rlcmac_dl_tbf::frames_since_last_drain(unsigned fn) const
+{
+	unsigned wrapped;
+	if (m_last_dl_drained_fn < 0)
+		return -1;
+
+	wrapped = (fn + 2715648 - m_last_dl_drained_fn) % 2715648;
+	if (wrapped < 2715648/2)
+		return wrapped;
+	else
+		return wrapped - 2715648;
+}
+
+bool gprs_rlcmac_dl_tbf::keep_open(unsigned fn) const
+{
+	int keep_time_frames;
+
+	if (bts_data()->dl_tbf_idle_msec <= 0)
+		return false;
+
+	keep_time_frames = msecs_to_frames(bts_data()->dl_tbf_idle_msec);
+	return frames_since_last_drain(fn) <= keep_time_frames;
+}