diff --git a/clock.c b/clock.c
index 30348dd..bec23c3 100644
--- a/clock.c
+++ b/clock.c
@@ -282,6 +282,7 @@ void clock_destroy(struct clock *c)
 	}
 	memset(c, 0, sizeof(*c));
 	msg_cleanup();
+	tc_cleanup();
 }
 
 static int clock_fault_timeout(struct port *port, int set)
diff --git a/makefile b/makefile
index d34eb6b..707c5d4 100644
--- a/makefile
+++ b/makefile
@@ -25,8 +25,8 @@ LDLIBS	= -lm -lrt $(EXTRA_LDFLAGS)
 PRG	= ptp4l hwstamp_ctl nsm phc2sys phc_ctl pmc timemaster
 OBJ     = bmc.o clock.o clockadj.o clockcheck.o config.o fault.o \
  filter.o fsm.o hash.o linreg.o mave.o mmedian.o msg.o ntpshm.o nullf.o phc.o \
- pi.o port.o print.o ptp4l.o raw.o rtnl.o servo.o sk.o stats.o telecom.o tlv.o \
- transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
+ pi.o port.o print.o ptp4l.o raw.o rtnl.o servo.o sk.o stats.o tc.o telecom.o \
+ tlv.o transport.o tsproc.o udp.o udp6.o uds.o util.o version.o
 
 OBJECTS	= $(OBJ) hwstamp_ctl.o nsm.o phc2sys.o phc_ctl.o pmc.o pmc_common.o \
  sysoff.o timemaster.o
diff --git a/port.c b/port.c
index d4352b0..55216ae 100644
--- a/port.c
+++ b/port.c
@@ -36,6 +36,7 @@
 #include "print.h"
 #include "rtnl.h"
 #include "sk.h"
+#include "tc.h"
 #include "tlv.h"
 #include "tmv.h"
 #include "tsproc.h"
@@ -1534,6 +1535,7 @@ void port_disable(struct port *p)
 {
 	int i;
 
+	tc_flush(p);
 	flush_last_sync(p);
 	flush_delay_req(p);
 	flush_peer_delay(p);
@@ -2777,6 +2779,7 @@ struct port *port_open(int phc_index,
 	}
 
 	memset(p, 0, sizeof(*p));
+	TAILQ_INIT(&p->tc_transmitted);
 
 	switch (type) {
 	case CLOCK_TYPE_ORDINARY:
diff --git a/port.h b/port.h
index d828875..9639193 100644
--- a/port.h
+++ b/port.h
@@ -322,4 +322,9 @@ enum fault_type last_fault_type(struct port *port);
 void fault_interval(struct port *port, enum fault_type ft,
 		    struct fault_interval *i);
 
+/**
+ * Release all of the memory in the TC transmit descriptor cache.
+ */
+void tc_cleanup(void);
+
 #endif
diff --git a/port_private.h b/port_private.h
index df6e39e..76dcab2 100644
--- a/port_private.h
+++ b/port_private.h
@@ -50,6 +50,13 @@ struct nrate_estimator {
 	int ratio_valid;
 };
 
+struct tc_txd {
+	TAILQ_ENTRY(tc_txd) list;
+	struct ptp_message *msg;
+	tmv_t residence;
+	int ingress_port;
+};
+
 struct port {
 	LIST_ENTRY(port) list;
 	char *name;
@@ -113,6 +120,7 @@ struct port {
 	int                 min_neighbor_prop_delay;
 	int                 net_sync_monitor;
 	int                 path_trace_enabled;
+	int                 tc_spanning_tree;
 	Integer64           rx_timestamp_offset;
 	Integer64           tx_timestamp_offset;
 	enum link_state     link_status;
@@ -121,6 +129,8 @@ struct port {
 	unsigned int        versionNumber; /*UInteger4*/
 	/* foreignMasterDS */
 	LIST_HEAD(fm, foreign_clock) foreign_masters;
+	/* TC book keeping */
+	TAILQ_HEAD(tct, tc_txd) tc_transmitted;
 };
 
 #define portnum(p) (p->portIdentity.portNumber)
diff --git a/tc.c b/tc.c
new file mode 100644
index 0000000..9b1d219
--- /dev/null
+++ b/tc.c
@@ -0,0 +1,510 @@
+/**
+ * @file tc.c
+ * @note Copyright (C) 2018 Richard Cochran <richardcochran@gmail.com>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA.
+ */
+#include <stdlib.h>
+
+#include "port.h"
+#include "print.h"
+#include "tc.h"
+#include "tmv.h"
+
+enum tc_match {
+	TC_MISMATCH,
+	TC_SYNC_FUP,
+	TC_FUP_SYNC,
+	TC_DELAY_REQRESP,
+};
+
+static TAILQ_HEAD(tc_pool, tc_txd) tc_pool = TAILQ_HEAD_INITIALIZER(tc_pool);
+
+static int tc_match_delay(int ingress_port, struct ptp_message *resp,
+			  struct tc_txd *txd);
+static int tc_match_syfup(int ingress_port, struct ptp_message *msg,
+			  struct tc_txd *txd);
+static void tc_recycle(struct tc_txd *txd);
+
+static struct tc_txd *tc_allocate(void)
+{
+	struct tc_txd *txd = TAILQ_FIRST(&tc_pool);
+
+	if (txd) {
+		TAILQ_REMOVE(&tc_pool, txd, list);
+		memset(txd, 0, sizeof(*txd));
+		return txd;
+	}
+	txd = calloc(1, sizeof(*txd));
+	return txd;
+}
+
+static int tc_blocked(struct port *q, struct port *p, struct ptp_message *m)
+{
+	enum port_state s;
+
+	if (q == p) {
+		return 1;
+	}
+	if (portnum(p) == 0) {
+		return 1;
+	}
+	if (!q->tc_spanning_tree) {
+		return 0;
+	}
+	/* Ingress state */
+	s = port_state(q);
+	switch (s) {
+	case PS_INITIALIZING:
+	case PS_FAULTY:
+	case PS_DISABLED:
+	case PS_LISTENING:
+	case PS_PRE_MASTER:
+	case PS_PASSIVE:
+		return 1;
+	case PS_MASTER:
+	case PS_GRAND_MASTER:
+		/* Delay_Req swims against the stream. */
+		if (msg_type(m) != DELAY_REQ) {
+			return 1;
+		}
+		break;
+	case PS_UNCALIBRATED:
+	case PS_SLAVE:
+		break;
+	}
+	/* Egress state */
+	s = port_state(p);
+	switch (s) {
+	case PS_INITIALIZING:
+	case PS_FAULTY:
+	case PS_DISABLED:
+	case PS_LISTENING:
+	case PS_PRE_MASTER:
+	case PS_PASSIVE:
+		return 1;
+	case PS_UNCALIBRATED:
+	case PS_SLAVE:
+		/* Delay_Req swims against the stream. */
+		if (msg_type(m) != DELAY_REQ) {
+			return 1;
+		}
+		break;
+	case PS_MASTER:
+	case PS_GRAND_MASTER:
+		/* No use forwarding Delay_Req out the wrong port. */
+		if (msg_type(m) == DELAY_REQ) {
+			return 1;
+		}
+		break;
+	}
+	return 0;
+}
+
+static void tc_complete_request(struct port *q, struct port *p,
+				struct ptp_message *req, tmv_t residence)
+{
+	struct tc_txd *txd = tc_allocate();
+	if (!txd) {
+		port_dispatch(p, EV_FAULT_DETECTED, 0);
+		return;
+	}
+#ifdef DEBUG
+	pr_err("stash delay request from port %hd to %hd seqid %hu residence %lu",
+	       portnum(q), portnum(p), ntohs(req->header.sequenceId),
+	       (unsigned long) tmv_to_nanoseconds(residence));
+#endif
+	msg_get(req);
+	txd->msg = req;
+	txd->residence = residence;
+	txd->ingress_port = portnum(q);
+	TAILQ_INSERT_TAIL(&p->tc_transmitted, txd, list);
+}
+
+static void tc_complete_response(struct port *q, struct port *p,
+				 struct ptp_message *resp, tmv_t residence)
+{
+	enum tc_match type = TC_MISMATCH;
+	struct tc_txd *txd;
+	Integer64 c1, c2;
+	int cnt;
+
+#ifdef DEBUG
+	pr_err("complete delay response from port %hd to %hd seqid %hu",
+	       portnum(q), portnum(p), ntohs(resp->header.sequenceId));
+#endif
+	TAILQ_FOREACH(txd, &q->tc_transmitted, list) {
+		type = tc_match_delay(portnum(p), resp, txd);
+		if (type == TC_DELAY_REQRESP) {
+			residence = txd->residence;
+			break;
+		}
+	}
+	if (type != TC_DELAY_REQRESP) {
+		return;
+	}
+	c1 = net2host64(resp->header.correction);
+	c2 = c1 + tmv_to_TimeInterval(residence);
+	resp->header.correction = host2net64(c2);
+	cnt = transport_send(p->trp, &p->fda, TRANS_GENERAL, resp);
+	if (cnt <= 0) {
+		pr_err("tc failed to forward response on port %d", portnum(p));
+		port_dispatch(p, EV_FAULT_DETECTED, 0);
+	}
+	/* Restore original correction value for next egress port. */
+	resp->header.correction = host2net64(c1);
+	TAILQ_REMOVE(&q->tc_transmitted, txd, list);
+	msg_put(txd->msg);
+	tc_recycle(txd);
+}
+
+static void tc_complete_syfup(struct port *q, struct port *p,
+			      struct ptp_message *msg, tmv_t residence)
+{
+	enum tc_match type = TC_MISMATCH;
+	struct ptp_message *fup;
+	struct tc_txd *txd;
+	Integer64 c1, c2;
+	int cnt;
+
+	TAILQ_FOREACH(txd, &p->tc_transmitted, list) {
+		type = tc_match_syfup(portnum(q), msg, txd);
+		switch (type) {
+		case TC_MISMATCH:
+			break;
+		case TC_SYNC_FUP:
+			fup = msg;
+			residence = txd->residence;
+			break;
+		case TC_FUP_SYNC:
+			fup = txd->msg;
+			break;
+		case TC_DELAY_REQRESP:
+			pr_err("tc: unexpected match of delay request - sync!");
+			return;
+		}
+		if (type != TC_MISMATCH) {
+			break;
+		}
+	}
+
+	if (type == TC_MISMATCH) {
+		txd = tc_allocate();
+		if (!txd) {
+			port_dispatch(p, EV_FAULT_DETECTED, 0);
+			return;
+		}
+		msg_get(msg);
+		txd->msg = msg;
+		txd->residence = residence;
+		txd->ingress_port = portnum(q);
+		TAILQ_INSERT_TAIL(&p->tc_transmitted, txd, list);
+		return;
+	}
+
+	c1 = net2host64(fup->header.correction);
+	c2 = c1 + tmv_to_TimeInterval(residence);
+	c2 += tmv_to_TimeInterval(q->peer_delay);
+	c2 += q->asymmetry;
+	fup->header.correction = host2net64(c2);
+	cnt = transport_send(p->trp, &p->fda, TRANS_GENERAL, fup);
+	if (cnt <= 0) {
+		pr_err("tc failed to forward follow up on port %d", portnum(p));
+		port_dispatch(p, EV_FAULT_DETECTED, 0);
+	}
+	/* Restore original correction value for next egress port. */
+	fup->header.correction = host2net64(c1);
+	TAILQ_REMOVE(&p->tc_transmitted, txd, list);
+	msg_put(txd->msg);
+	tc_recycle(txd);
+}
+
+static void tc_complete(struct port *q, struct port *p,
+			struct ptp_message *msg, tmv_t residence)
+{
+	switch (msg_type(msg)) {
+	case SYNC:
+	case FOLLOW_UP:
+		tc_complete_syfup(q, p, msg, residence);
+		break;
+	case DELAY_REQ:
+		tc_complete_request(q, p, msg, residence);
+		break;
+	case DELAY_RESP:
+		tc_complete_response(q, p, msg, residence);
+		break;
+	}
+}
+
+static int tc_current(struct ptp_message *m, struct timespec now)
+{
+	int64_t t1, t2, tmo;
+
+	tmo = 1LL * NSEC2SEC;
+	t1 = m->ts.host.tv_sec * NSEC2SEC + m->ts.host.tv_nsec;
+	t2 = now.tv_sec * NSEC2SEC + now.tv_nsec;
+
+	return t2 - t1 < tmo;
+}
+
+static int tc_fwd_event(struct port *q, struct ptp_message *msg)
+{
+	tmv_t egress, ingress = msg->hwts.ts, residence;
+	struct port *p;
+	int cnt, err;
+	double rr;
+
+	clock_gettime(CLOCK_MONOTONIC, &msg->ts.host);
+
+	/* First send the event message out. */
+	for (p = clock_first_port(q->clock); p; p = LIST_NEXT(p, list)) {
+		if (tc_blocked(q, p, msg)) {
+			continue;
+		}
+		cnt = transport_send(p->trp, &p->fda, TRANS_DEFER_EVENT, msg);
+		if (cnt <= 0) {
+			pr_err("failed to forward event from port %hd to %hd",
+				portnum(q), portnum(p));
+			port_dispatch(p, EV_FAULT_DETECTED, 0);
+		}
+	}
+
+	/* Go back and gather the transmit time stamps. */
+	for (p = clock_first_port(q->clock); p; p = LIST_NEXT(p, list)) {
+		if (tc_blocked(q, p, msg)) {
+			continue;
+		}
+		err = transport_txts(p->trp, &p->fda, msg);
+		if (err || !msg_sots_valid(msg)) {
+			pr_err("failed to fetch txts on port %hd to %hd event",
+				portnum(q), portnum(p));
+			port_dispatch(p, EV_FAULT_DETECTED, 0);
+			continue;
+		}
+		ts_add(&msg->hwts.ts, p->tx_timestamp_offset);
+		egress = msg->hwts.ts;
+		residence = tmv_sub(egress, ingress);
+		rr = clock_rate_ratio(q->clock);
+		if (rr != 1.0) {
+			residence = dbl_tmv(tmv_dbl(residence) * rr);
+		}
+		tc_complete(q, p, msg, residence);
+	}
+
+	return 0;
+}
+
+static int tc_match_delay(int ingress_port, struct ptp_message *resp,
+			  struct tc_txd *txd)
+{
+	struct ptp_message *req = txd->msg;
+
+	if (ingress_port != txd->ingress_port) {
+		return TC_MISMATCH;
+	}
+	if (req->header.sequenceId != resp->header.sequenceId) {
+		return TC_MISMATCH;
+	}
+	if (!pid_eq(&req->header.sourcePortIdentity,
+		    &resp->delay_resp.requestingPortIdentity)) {
+		return TC_MISMATCH;
+	}
+	if (msg_type(req) == DELAY_REQ && msg_type(resp) == DELAY_RESP) {
+		return TC_DELAY_REQRESP;
+	}
+	return TC_MISMATCH;
+}
+
+static int tc_match_syfup(int ingress_port, struct ptp_message *msg,
+			  struct tc_txd *txd)
+{
+	if (ingress_port != txd->ingress_port) {
+		return TC_MISMATCH;
+	}
+	if (msg->header.sequenceId != txd->msg->header.sequenceId) {
+		return TC_MISMATCH;
+	}
+	if (!source_pid_eq(msg, txd->msg)) {
+		return TC_MISMATCH;
+	}
+	if (msg_type(txd->msg) == SYNC && msg_type(msg) == FOLLOW_UP) {
+		return TC_SYNC_FUP;
+	}
+	if (msg_type(txd->msg) == FOLLOW_UP && msg_type(msg) == SYNC) {
+		return TC_FUP_SYNC;
+	}
+	return TC_MISMATCH;
+}
+
+static void tc_recycle(struct tc_txd *txd)
+{
+	TAILQ_INSERT_HEAD(&tc_pool, txd, list);
+}
+
+/* public methods */
+
+void tc_cleanup(void)
+{
+	struct tc_txd *txd;
+
+	while ((txd = TAILQ_FIRST(&tc_pool)) != NULL) {
+		TAILQ_REMOVE(&tc_pool, txd, list);
+		free(txd);
+	}
+}
+
+void tc_flush(struct port *q)
+{
+	struct tc_txd *txd;
+
+	while ((txd = TAILQ_FIRST(&q->tc_transmitted)) != NULL) {
+		TAILQ_REMOVE(&q->tc_transmitted, txd, list);
+		msg_put(txd->msg);
+		tc_recycle(txd);
+	}
+}
+
+int tc_forward(struct port *q, struct ptp_message *msg)
+{
+	uint16_t steps_removed;
+	struct port *p;
+	int cnt;
+
+	if (q->tc_spanning_tree && msg_type(msg) == ANNOUNCE) {
+		steps_removed = ntohs(msg->announce.stepsRemoved);
+		msg->announce.stepsRemoved = htons(1 + steps_removed);
+	}
+
+	for (p = clock_first_port(q->clock); p; p = LIST_NEXT(p, list)) {
+		if (tc_blocked(q, p, msg)) {
+			continue;
+		}
+		cnt = transport_send(p->trp, &p->fda, TRANS_GENERAL, msg);
+		if (cnt <= 0) {
+			pr_err("tc failed to forward message on port %d",
+			       portnum(p));
+			port_dispatch(p, EV_FAULT_DETECTED, 0);
+		}
+	}
+	return 0;
+}
+
+int tc_fwd_folup(struct port *q, struct ptp_message *msg)
+{
+	struct port *p;
+
+	clock_gettime(CLOCK_MONOTONIC, &msg->ts.host);
+
+	for (p = clock_first_port(q->clock); p; p = LIST_NEXT(p, list)) {
+		if (tc_blocked(q, p, msg)) {
+			continue;
+		}
+		tc_complete(q, p, msg, tmv_zero());
+	}
+	return 0;
+}
+
+int tc_fwd_request(struct port *q, struct ptp_message *msg)
+{
+	return tc_fwd_event(q, msg);
+}
+
+int tc_fwd_response(struct port *q, struct ptp_message *msg)
+{
+	struct port *p;
+
+	clock_gettime(CLOCK_MONOTONIC, &msg->ts.host);
+
+	for (p = clock_first_port(q->clock); p; p = LIST_NEXT(p, list)) {
+		if (tc_blocked(q, p, msg)) {
+			continue;
+		}
+		tc_complete(q, p, msg, tmv_zero());
+	}
+	return 0;
+}
+
+int tc_fwd_sync(struct port *q, struct ptp_message *msg)
+{
+	struct ptp_message *fup = NULL;
+	int err;
+
+	if (one_step(msg)) {
+		fup = msg_allocate();
+		if (!fup) {
+			return -1;
+		}
+		fup->header.tsmt               = FOLLOW_UP | (msg->header.tsmt & 0xf0);
+		fup->header.ver                = msg->header.ver;
+		fup->header.messageLength      = sizeof(struct follow_up_msg);
+		fup->header.domainNumber       = msg->header.domainNumber;
+		fup->header.sourcePortIdentity = msg->header.sourcePortIdentity;
+		fup->header.sequenceId         = msg->header.sequenceId;
+		fup->header.control            = CTL_FOLLOW_UP;
+		fup->header.logMessageInterval = msg->header.logMessageInterval;
+		fup->follow_up.preciseOriginTimestamp = msg->sync.originTimestamp;
+		msg->header.flagField[0]      |= TWO_STEP;
+	}
+	err = tc_fwd_event(q, msg);
+	if (err) {
+		return err;
+	}
+	if (fup) {
+		err = tc_fwd_folup(q, fup);
+		msg_put(fup);
+	}
+	return err;
+}
+
+int tc_ignore(struct port *p, struct ptp_message *m)
+{
+	struct ClockIdentity c1, c2;
+
+	if (p->match_transport_specific &&
+	    msg_transport_specific(m) != p->transportSpecific) {
+		return 1;
+	}
+	if (pid_eq(&m->header.sourcePortIdentity, &p->portIdentity)) {
+		return 1;
+	}
+	if (m->header.domainNumber != clock_domain_number(p->clock)) {
+		return 1;
+	}
+
+	c1 = clock_identity(p->clock);
+	c2 = m->header.sourcePortIdentity.clockIdentity;
+
+	if (0 == memcmp(&c1, &c2, sizeof(c1))) {
+		return 1;
+	}
+	return 0;
+}
+
+void tc_prune(struct port *q)
+{
+	struct timespec now;
+	struct tc_txd *txd;
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	while ((txd = TAILQ_FIRST(&q->tc_transmitted)) != NULL) {
+		if (tc_current(txd->msg, now)) {
+			break;
+		}
+		TAILQ_REMOVE(&q->tc_transmitted, txd, list);
+		msg_put(txd->msg);
+		tc_recycle(txd);
+	}
+}
diff --git a/tc.h b/tc.h
new file mode 100644
index 0000000..ef82351
--- /dev/null
+++ b/tc.h
@@ -0,0 +1,103 @@
+/**
+ * @file tc.h
+ * @brief Provides Transparent Clock logic.
+ * @note Copyright (C) 2018 Richard Cochran <richardcochran@gmail.com>
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA.
+ */
+#ifndef HAVE_TC_H
+#define HAVE_TC_H
+
+#include "msg.h"
+#include "port_private.h"
+
+/**
+ * Flushes the list of remembered residence times.
+ * @param q    Port whose list should be flushed
+ */
+void tc_flush(struct port *q);
+
+/**
+ * Forwards a given general message out all other ports.
+ * @param q    The ingress port
+ * @param msg  The message to be sent
+ * @return     Zero on success, non-zero otherwise.
+ */
+int tc_forward(struct port *q, struct ptp_message *msg);
+
+/**
+ * Forwards a given Follow-Up message out all other ports.
+ *
+ * This function adds the unique, per egress port residence time into
+ * the correction field for the transmitted follow up message.
+ *
+ * @param q    The ingress port
+ * @param msg  The message to be sent
+ * @return     Zero on success, non-zero otherwise.
+ */
+int tc_fwd_folup(struct port *q, struct ptp_message *msg);
+
+/**
+ * Forwards a given delay request message out all other ports.
+ *
+ * This function computes the unique residence time for each egress
+ * port, remembering it in that egress port.
+ *
+ * @param q    The ingress port
+ * @param msg  The message to be sent
+ * @return     Zero on success, non-zero otherwise.
+ */
+int tc_fwd_request(struct port *q, struct ptp_message *msg);
+
+/**
+ * Forwards a given response message out all other ports.
+ *
+ * This function adds the unique, per egress port residence time into
+ * the correction field for the transmitted delay response message.
+ *
+ * @param q    The ingress port
+ * @param msg  The message to be sent
+ * @return     Zero on success, non-zero otherwise.
+ */
+int tc_fwd_response(struct port *q, struct ptp_message *msg);
+
+/**
+ * Forwards a given sync message out all other ports.
+ *
+ * This function computes the unique residence time for each egress
+ * port, remembering it in that egress port.
+ *
+ * @param q    The ingress port
+ * @param msg  The message to be sent
+ * @return     Zero on success, non-zero otherwise.
+ */
+int tc_fwd_sync(struct port *q, struct ptp_message *msg);
+
+/**
+ * Determines whether the local clock should ignore a given message.
+ *
+ * @param q    The ingress port
+ * @param msg  The message to test
+ * @return     One if the message should be ignored, zero otherwise.
+ */
+int tc_ignore(struct port *q, struct ptp_message *m);
+
+/**
+ * Prunes stale entries from the list of remembered residence times.
+ * @param q    Port whose list should be pruned.
+ */
+void tc_prune(struct port *q);
+
+#endif