Index: sys/netinet/cc/cc_dctcp.c
===================================================================
--- sys/netinet/cc/cc_dctcp.c
+++ sys/netinet/cc/cc_dctcp.c
@@ -109,7 +109,7 @@
 
 	dctcp_data = ccv->cc_data;
 
-	if (CCV(ccv, t_flags) & TF_ECN_PERMIT) {
+	if (CCV(ccv, t_flags2) & TF2_ECN_PERMIT) {
 		/*
 		 * DCTCP doesn't treat receipt of ECN marked packet as a
 		 * congestion event. Thus, DCTCP always executes the ACK
@@ -168,7 +168,7 @@
 {
 	struct dctcp *dctcp_data;
 
-	if (CCV(ccv, t_flags) & TF_ECN_PERMIT) {
+	if (CCV(ccv, t_flags2) & TF2_ECN_PERMIT) {
 		dctcp_data = ccv->cc_data;
 
 		/* Initialize internal parameters after idle time */
@@ -234,7 +234,7 @@
 	struct dctcp *dctcp_data;
 	u_int cwin, mss;
 
-	if (CCV(ccv, t_flags) & TF_ECN_PERMIT) {
+	if (CCV(ccv, t_flags2) & TF2_ECN_PERMIT) {
 		dctcp_data = ccv->cc_data;
 		cwin = CCV(ccv, snd_cwnd);
 		mss = CCV(ccv, t_maxseg);
@@ -284,7 +284,7 @@
 			dctcp_data->ece_curr = 1;
 			break;
 		case CC_RTO:
-			CCV(ccv, t_flags) |= TF_ECN_SND_CWR;
+			CCV(ccv, t_flags2) |= TF2_ECN_SND_CWR;
 			dctcp_update_alpha(ccv);
 			dctcp_data->save_sndnxt += CCV(ccv, t_maxseg);
 			dctcp_data->num_cong_events++;
@@ -301,7 +301,7 @@
 
 	dctcp_data = ccv->cc_data;
 
-	if (CCV(ccv, t_flags) & TF_ECN_PERMIT)
+	if (CCV(ccv, t_flags2) & TF2_ECN_PERMIT)
 		dctcp_data->save_sndnxt = CCV(ccv, snd_nxt);
 }
 
@@ -313,7 +313,7 @@
 {
 	newreno_cc_algo.post_recovery(ccv);
 
-	if (CCV(ccv, t_flags) & TF_ECN_PERMIT)
+	if (CCV(ccv, t_flags2) & TF2_ECN_PERMIT)
 		dctcp_update_alpha(ccv);
 }
 
@@ -344,12 +344,12 @@
 		if (!dctcp_data->ce_prev && (ccflag & CCF_DELACK))
 			delay_ack = 0;
 		dctcp_data->ce_prev = 1;
-		CCV(ccv, t_flags) |= TF_ECN_SND_ECE;
+		CCV(ccv, t_flags2) |= TF2_ECN_SND_ECE;
 	} else {
 		if (dctcp_data->ce_prev && (ccflag & CCF_DELACK))
 			delay_ack = 0;
 		dctcp_data->ce_prev = 0;
-		CCV(ccv, t_flags) &= ~TF_ECN_SND_ECE;
+		CCV(ccv, t_flags2) &= ~TF2_ECN_SND_ECE;
 	}
 
 	/* DCTCP sets delayed ack when this segment sets the CWR flag. */
Index: sys/netinet/tcp_input.c
===================================================================
--- sys/netinet/tcp_input.c
+++ sys/netinet/tcp_input.c
@@ -390,16 +390,16 @@
 	case CC_NDUPACK:
 		if (!IN_FASTRECOVERY(tp->t_flags)) {
 			tp->snd_recover = tp->snd_max;
-			if (tp->t_flags & TF_ECN_PERMIT)
-				tp->t_flags |= TF_ECN_SND_CWR;
+			if (tp->t_flags2 & TF2_ECN_PERMIT)
+				tp->t_flags2 |= TF2_ECN_SND_CWR;
 		}
 		break;
 	case CC_ECN:
 		if (!IN_CONGRECOVERY(tp->t_flags)) {
 			TCPSTAT_INC(tcps_ecn_rcwnd);
 			tp->snd_recover = tp->snd_max;
-			if (tp->t_flags & TF_ECN_PERMIT)
-				tp->t_flags |= TF_ECN_SND_CWR;
+			if (tp->t_flags2 & TF2_ECN_PERMIT)
+				tp->t_flags2 |= TF2_ECN_SND_CWR;
 		}
 		break;
 	case CC_RTO:
@@ -1489,12 +1489,12 @@
 	/*
 	 * TCP ECN processing.
 	 */
-	if (tp->t_flags & TF_ECN_PERMIT) {
+	if (tp->t_flags2 & TF2_ECN_PERMIT) {
 		if (thflags & TH_CWR)
-			tp->t_flags &= ~TF_ECN_SND_ECE;
+			tp->t_flags2 &= ~TF2_ECN_SND_ECE;
 		switch (iptos & IPTOS_ECN_MASK) {
 		case IPTOS_ECN_CE:
-			tp->t_flags |= TF_ECN_SND_ECE;
+			tp->t_flags2 |= TF2_ECN_SND_ECE;
 			TCPSTAT_INC(tcps_ecn_ce);
 			break;
 		case IPTOS_ECN_ECT0:
@@ -1923,7 +1923,7 @@
 
 			if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) &&
 			    V_tcp_do_ecn) {
-				tp->t_flags |= TF_ECN_PERMIT;
+				tp->t_flags2 |= TF2_ECN_PERMIT;
 				TCPSTAT_INC(tcps_ecn_shs);
 			}
 			
Index: sys/netinet/tcp_output.c
===================================================================
--- sys/netinet/tcp_output.c
+++ sys/netinet/tcp_output.c
@@ -1135,7 +1135,7 @@
 	}
 	
 	if (tp->t_state == TCPS_ESTABLISHED &&
-	    (tp->t_flags & TF_ECN_PERMIT)) {
+	    (tp->t_flags2 & TF2_ECN_PERMIT)) {
 		/*
 		 * If the peer has ECN, mark data packets with
 		 * ECN capable transmission (ECT).
@@ -1155,11 +1155,11 @@
 		/*
 		 * Reply with proper ECN notifications.
 		 */
-		if (tp->t_flags & TF_ECN_SND_CWR) {
+		if (tp->t_flags2 & TF2_ECN_SND_CWR) {
 			flags |= TH_CWR;
-			tp->t_flags &= ~TF_ECN_SND_CWR;
+			tp->t_flags2 &= ~TF2_ECN_SND_CWR;
 		} 
-		if (tp->t_flags & TF_ECN_SND_ECE)
+		if (tp->t_flags2 & TF2_ECN_SND_ECE)
 			flags |= TH_ECE;
 	}
 	
Index: sys/netinet/tcp_stacks/rack.c
===================================================================
--- sys/netinet/tcp_stacks/rack.c
+++ sys/netinet/tcp_stacks/rack.c
@@ -1809,16 +1809,16 @@
 			rack_log_to_prr(rack, 2);
 			rack->r_ctl.rc_prr_recovery_fs = tp->snd_max - tp->snd_una;
 			tp->snd_recover = tp->snd_max;
-			if (tp->t_flags & TF_ECN_PERMIT)
-				tp->t_flags |= TF_ECN_SND_CWR;
+			if (tp->t_flags2 & TF2_ECN_PERMIT)
+				tp->t_flags2 |= TF2_ECN_SND_CWR;
 		}
 		break;
 	case CC_ECN:
 		if (!IN_CONGRECOVERY(tp->t_flags)) {
 			TCPSTAT_INC(tcps_ecn_rcwnd);
 			tp->snd_recover = tp->snd_max;
-			if (tp->t_flags & TF_ECN_PERMIT)
-				tp->t_flags |= TF_ECN_SND_CWR;
+			if (tp->t_flags2 & TF2_ECN_PERMIT)
+				tp->t_flags2 |= TF2_ECN_SND_CWR;
 		}
 		break;
 	case CC_RTO:
@@ -6307,7 +6307,7 @@
 
 		if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) &&
 		    V_tcp_do_ecn) {
-			tp->t_flags |= TF_ECN_PERMIT;
+			tp->t_flags2 |= TF2_ECN_PERMIT;
 			TCPSTAT_INC(tcps_ecn_shs);
 		}
 		if (SEQ_GT(th->th_ack, tp->snd_una)) {
@@ -7708,12 +7708,12 @@
 	 * TCP ECN processing. XXXJTL: If we ever use ECN, we need to move
 	 * this to occur after we've validated the segment.
 	 */
-	if (tp->t_flags & TF_ECN_PERMIT) {
+	if (tp->t_flags2 & TF2_ECN_PERMIT) {
 		if (thflags & TH_CWR)
-			tp->t_flags &= ~TF_ECN_SND_ECE;
+			tp->t_flags2 &= ~TF2_ECN_SND_ECE;
 		switch (iptos & IPTOS_ECN_MASK) {
 		case IPTOS_ECN_CE:
-			tp->t_flags |= TF_ECN_SND_ECE;
+			tp->t_flags2 |= TF2_ECN_SND_ECE;
 			TCPSTAT_INC(tcps_ecn_ce);
 			break;
 		case IPTOS_ECN_ECT0:
@@ -9470,7 +9470,7 @@
 			flags |= TH_ECE | TH_CWR;
 	}
 	if (tp->t_state == TCPS_ESTABLISHED &&
-	    (tp->t_flags & TF_ECN_PERMIT)) {
+	    (tp->t_flags2 & TF2_ECN_PERMIT)) {
 		/*
 		 * If the peer has ECN, mark data packets with ECN capable
 		 * transmission (ECT). Ignore pure ack packets,
@@ -9489,11 +9489,11 @@
 		/*
 		 * Reply with proper ECN notifications.
 		 */
-		if (tp->t_flags & TF_ECN_SND_CWR) {
+		if (tp->t_flags2 & TF2_ECN_SND_CWR) {
 			flags |= TH_CWR;
-			tp->t_flags &= ~TF_ECN_SND_CWR;
+			tp->t_flags2 &= ~TF2_ECN_SND_CWR;
 		}
-		if (tp->t_flags & TF_ECN_SND_ECE)
+		if (tp->t_flags2 & TF2_ECN_SND_ECE)
 			flags |= TH_ECE;
 	}
 	/*
Index: sys/netinet/tcp_syncache.c
===================================================================
--- sys/netinet/tcp_syncache.c
+++ sys/netinet/tcp_syncache.c
@@ -1023,7 +1023,7 @@
 	}
 
 	if (sc->sc_flags & SCF_ECN)
-		tp->t_flags |= TF_ECN_PERMIT;
+		tp->t_flags2 |= TF2_ECN_PERMIT;
 
 	/*
 	 * Set up MSS and get cached values from tcp_hostcache.
Index: sys/netinet/tcp_usrreq.c
===================================================================
--- sys/netinet/tcp_usrreq.c
+++ sys/netinet/tcp_usrreq.c
@@ -1572,7 +1572,7 @@
 		ti->tcpi_snd_wscale = tp->snd_scale;
 		ti->tcpi_rcv_wscale = tp->rcv_scale;
 	}
-	if (tp->t_flags & TF_ECN_PERMIT)
+	if (tp->t_flags2 & TF2_ECN_PERMIT)
 		ti->tcpi_options |= TCPI_OPT_ECN;
 
 	ti->tcpi_rto = tp->t_rxtcur * tick;
@@ -2610,16 +2610,25 @@
 		db_printf("%sTF_TSO", comma ? ", " : "");
 		comma = 1;
 	}
-	if (t_flags & TF_ECN_PERMIT) {
-		db_printf("%sTF_ECN_PERMIT", comma ? ", " : "");
-		comma = 1;
-	}
 	if (t_flags & TF_FASTOPEN) {
 		db_printf("%sTF_FASTOPEN", comma ? ", " : "");
 		comma = 1;
 	}
 }
 
+static void
+db_print_tflags2(u_int t_flags2)
+{
+	int comma;
+
+	comma = 0;
+	if (t_flags2 & TF2_ECN_PERMIT) {
+		db_printf("%sTF2_ECN_PERMIT", comma ? ", " : "");
+		comma = 1;
+	}
+}
+
+
 static void
 db_print_toobflags(char t_oobflags)
 {
@@ -2667,6 +2676,11 @@
 	db_print_tflags(tp->t_flags);
 	db_printf(")\n");
 
+	db_print_indent(indent);
+	db_printf("t_flags2: 0x%x (", tp->t_flags2);
+	db_print_tflags2(tp->t_flags2);
+	db_printf(")\n");
+
 	db_print_indent(indent);
 	db_printf("snd_una: 0x%08x   snd_max: 0x%08x   snd_nxt: x0%08x\n",
 	    tp->snd_una, tp->snd_max, tp->snd_nxt);
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -326,6 +326,8 @@
 #define	TF_NEEDFIN	0x000800	/* send FIN (implicit state) */
 #define	TF_NOPUSH	0x001000	/* don't push */
 #define	TF_PREVVALID	0x002000	/* saved values for bad rxmit valid */
+#define	TF_UNUSED1	0x00004000	/* unused */
+#define	TF_UNUSED2	0x00008000	/* unused */
 #define	TF_MORETOCOME	0x010000	/* More data to be appended to sock */
 #define	TF_LQ_OVERFLOW	0x020000	/* listen queue overflow */
 #define	TF_LASTIDLE	0x040000	/* connection was previously idle */
@@ -336,9 +338,9 @@
 #define	TF_FORCEDATA	0x800000	/* force out a byte */
 #define	TF_TSO		0x1000000	/* TSO enabled on this connection */
 #define	TF_TOE		0x2000000	/* this connection is offloaded */
-#define	TF_ECN_PERMIT	0x4000000	/* connection ECN-ready */
-#define	TF_ECN_SND_CWR	0x8000000	/* ECN CWR in queue */
-#define	TF_ECN_SND_ECE	0x10000000	/* ECN ECE in queue */
+#define	TF_UNUSED3	0x4000000	/* unused */
+#define	TF_UNUSED4	0x8000000	/* unused */
+#define	TF_UNUSED5	0x10000000	/* unused */
 #define	TF_CONGRECOVERY	0x20000000	/* congestion recovery mode */
 #define	TF_WASCRECOVERY	0x40000000	/* was in congestion recovery */
 #define	TF_FASTOPEN	0x80000000	/* TCP Fast Open indication */
@@ -377,6 +379,10 @@
 #define	TF2_PLPMTU_MAXSEGSNT	0x00000004 /* Last seg sent was full seg. */
 #define	TF2_LOG_AUTO		0x00000008 /* Session is auto-logging. */
 #define TF2_DROP_AF_DATA 	0x00000010 /* Drop after all data ack'd */
+#define	TF2_ECN_PERMIT		0x00000020 /* connection ECN-ready */
+#define	TF2_ECN_SND_CWR		0x00000040 /* ECN CWR in queue */
+#define	TF2_ECN_SND_ECE		0x00000080 /* ECN ECE in queue */
+#define	TF2_ACE_PERMIT		0x00000100 /* Accurate ECN mode */
 
 /*
  * Structure to hold TCP options that are only used during segment