diff --git a/sys/netinet/sctp.h b/sys/netinet/sctp.h
index 403bea4ca63..1e86415f3f0 100644
--- a/sys/netinet/sctp.h
+++ b/sys/netinet/sctp.h
@@ -263,6 +263,7 @@ struct sctp_paramhdr {
 
 #define SCTP_CC_OPT_RTCC_SETMODE	0x00002000
 #define SCTP_CC_OPT_USE_DCCC_ECN	0x00002001
+#define SCTP_CC_OPT_STEADY_STEP         0x00002002
 
 /* RS - Supported stream scheduling modules for pluggable
  * stream scheduling
diff --git a/sys/netinet/sctp_cc_functions.c b/sys/netinet/sctp_cc_functions.c
index dd5aab0ff16..3d52820772b 100644
--- a/sys/netinet/sctp_cc_functions.c
+++ b/sys/netinet/sctp_cc_functions.c
@@ -185,6 +185,328 @@ sctp_cwnd_update_after_fr(struct sctp_tcb *stcb,
 	}
 }
 
+/* Defines for instantaneous bw decisions */
+#define SCTP_INST_LOOSING 1	/* Loosing to other flows */
+#define SCTP_INST_NEUTRAL 2	/* Neutral, no indication */
+#define SCTP_INST_GAINING 3	/* Gaining, step down possible */
+
+
+static int
+cc_bw_same(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw,
+    uint64_t rtt_offset, uint64_t vtag, uint8_t inst_ind)
+{
+	uint64_t oth, probepoint;
+
+	probepoint = (((uint64_t) net->cwnd) << 32);
+	if (net->rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
+		/*
+		 * rtt increased we don't update bw.. so we don't update the
+		 * rtt either.
+		 */
+		/* Probe point 5 */
+		probepoint |= ((5 << 16) | 1);
+		SDT_PROBE(sctp, cwnd, net, rttvar,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    net->flight_size,
+		    probepoint);
+		if ((net->cc_mod.rtcc.steady_step) && (inst_ind != SCTP_INST_LOOSING)) {
+			if (net->cc_mod.rtcc.last_step_state == 5)
+				net->cc_mod.rtcc.step_cnt++;
+			else
+				net->cc_mod.rtcc.step_cnt = 1;
+			net->cc_mod.rtcc.last_step_state = 5;
+			if ((net->cc_mod.rtcc.step_cnt == net->cc_mod.rtcc.steady_step) ||
+			    ((net->cc_mod.rtcc.step_cnt > net->cc_mod.rtcc.steady_step) &&
+			    ((net->cc_mod.rtcc.step_cnt % net->cc_mod.rtcc.steady_step) == 0))) {
+				/* Try a step down */
+				oth = net->cc_mod.rtcc.vol_reduce;
+				oth <<= 16;
+				oth |= net->cc_mod.rtcc.step_cnt;
+				oth <<= 16;
+				oth |= net->cc_mod.rtcc.last_step_state;
+				SDT_PROBE(sctp, cwnd, net, rttstep,
+				    vtag,
+				    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+				    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+				    oth,
+				    probepoint);
+				if (net->cwnd > (4 * net->mtu)) {
+					net->cwnd -= net->mtu;
+					net->cc_mod.rtcc.vol_reduce++;
+				} else {
+					net->cc_mod.rtcc.step_cnt = 0;
+				}
+			}
+		}
+		return (1);
+	}
+	if (net->rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
+		/*
+		 * rtt decreased, there could be more room. we update both
+		 * the bw and the rtt here to lock this in as a good step
+		 * down.
+		 */
+		/* Probe point 6 */
+		probepoint |= ((6 << 16) | 0);
+		SDT_PROBE(sctp, cwnd, net, rttvar,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    net->flight_size,
+		    probepoint);
+		if (net->cc_mod.rtcc.steady_step) {
+			oth = net->cc_mod.rtcc.vol_reduce;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.step_cnt;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.last_step_state;
+			SDT_PROBE(sctp, cwnd, net, rttstep,
+			    vtag,
+			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+			    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+			    oth,
+			    probepoint);
+			if ((net->cc_mod.rtcc.last_step_state == 5) &&
+			    (net->cc_mod.rtcc.step_cnt > net->cc_mod.rtcc.steady_step)) {
+				/* Step down worked */
+				net->cc_mod.rtcc.step_cnt = 0;
+				return (1);
+			} else {
+				net->cc_mod.rtcc.last_step_state = 6;
+				net->cc_mod.rtcc.step_cnt = 0;
+			}
+		}
+		net->cc_mod.rtcc.lbw = nbw;
+		net->cc_mod.rtcc.lbw_rtt = net->rtt;
+		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
+		if (inst_ind == SCTP_INST_GAINING)
+			return (1);
+		else if (inst_ind == SCTP_INST_NEUTRAL)
+			return (1);
+		else
+			return (0);
+	}
+	/*
+	 * Ok bw and rtt remained the same .. no update to any
+	 */
+	/* Probe point 7 */
+	probepoint |= ((7 << 16) | net->cc_mod.rtcc.ret_from_eq);
+	SDT_PROBE(sctp, cwnd, net, rttvar,
+	    vtag,
+	    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+	    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+	    net->flight_size,
+	    probepoint);
+
+	if ((net->cc_mod.rtcc.steady_step) && (inst_ind != SCTP_INST_LOOSING)) {
+		if (net->cc_mod.rtcc.last_step_state == 5)
+			net->cc_mod.rtcc.step_cnt++;
+		else
+			net->cc_mod.rtcc.step_cnt = 1;
+		net->cc_mod.rtcc.last_step_state = 5;
+		if ((net->cc_mod.rtcc.step_cnt == net->cc_mod.rtcc.steady_step) ||
+		    ((net->cc_mod.rtcc.step_cnt > net->cc_mod.rtcc.steady_step) &&
+		    ((net->cc_mod.rtcc.step_cnt % net->cc_mod.rtcc.steady_step) == 0))) {
+			/* Try a step down */
+			if (net->cwnd > (4 * net->mtu)) {
+				net->cwnd -= net->mtu;
+				net->cc_mod.rtcc.vol_reduce++;
+				return (1);
+			} else {
+				net->cc_mod.rtcc.step_cnt = 0;
+			}
+		}
+	}
+	if (inst_ind == SCTP_INST_GAINING)
+		return (1);
+	else if (inst_ind == SCTP_INST_NEUTRAL)
+		return (1);
+	else
+		return ((int)net->cc_mod.rtcc.ret_from_eq);
+}
+
+static int
+cc_bw_decrease(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw, uint64_t rtt_offset,
+    uint64_t vtag, uint8_t inst_ind)
+{
+	uint64_t oth, probepoint;
+
+	/* Bandwidth decreased. */
+	probepoint = (((uint64_t) net->cwnd) << 32);
+	if (net->rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
+		/* rtt increased */
+		/* Did we add more */
+		if ((net->cwnd > net->cc_mod.rtcc.cwnd_at_bw_set) &&
+		    (inst_ind != SCTP_INST_LOOSING)) {
+			/* We caused it maybe.. back off? */
+			/* PROBE POINT 1 */
+			probepoint |= ((1 << 16) | 1);
+			SDT_PROBE(sctp, cwnd, net, rttvar,
+			    vtag,
+			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+			    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+			    net->flight_size,
+			    probepoint);
+
+			if (net->cc_mod.rtcc.ret_from_eq) {
+				/*
+				 * Switch over to CA if we are less
+				 * aggressive
+				 */
+				net->ssthresh = net->cwnd - 1;
+				net->partial_bytes_acked = 0;
+			}
+			return (1);
+		}
+		/* Probe point 2 */
+		probepoint |= ((2 << 16) | 0);
+		SDT_PROBE(sctp, cwnd, net, rttvar,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    net->flight_size,
+		    probepoint);
+
+		/* Someone else - fight for more? */
+		if (net->cc_mod.rtcc.steady_step) {
+			oth = net->cc_mod.rtcc.vol_reduce;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.step_cnt;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.last_step_state;
+			SDT_PROBE(sctp, cwnd, net, rttstep,
+			    vtag,
+			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+			    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+			    oth,
+			    probepoint);
+			/*
+			 * Did we voluntarily give up some? if so take one
+			 * back please
+			 */
+			if ((net->cc_mod.rtcc.vol_reduce) &&
+			    (inst_ind != SCTP_INST_GAINING)) {
+				net->cwnd += net->mtu;
+				net->cc_mod.rtcc.vol_reduce--;
+			}
+			net->cc_mod.rtcc.last_step_state = 2;
+			net->cc_mod.rtcc.step_cnt = 0;
+		}
+		goto out_decision;
+	} else if (net->rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
+		/* bw & rtt decreased */
+		/* Probe point 3 */
+		probepoint |= ((3 << 16) | 0);
+		SDT_PROBE(sctp, cwnd, net, rttvar,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    net->flight_size,
+		    probepoint);
+		if (net->cc_mod.rtcc.steady_step) {
+			oth = net->cc_mod.rtcc.vol_reduce;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.step_cnt;
+			oth <<= 16;
+			oth |= net->cc_mod.rtcc.last_step_state;
+			SDT_PROBE(sctp, cwnd, net, rttstep,
+			    vtag,
+			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+			    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+			    oth,
+			    probepoint);
+			if ((net->cc_mod.rtcc.vol_reduce) &&
+			    (inst_ind != SCTP_INST_GAINING)) {
+				net->cwnd += net->mtu;
+				net->cc_mod.rtcc.vol_reduce--;
+			}
+			net->cc_mod.rtcc.last_step_state = 3;
+			net->cc_mod.rtcc.step_cnt = 0;
+		}
+		goto out_decision;
+	}
+	/* The bw decreased but rtt stayed the same */
+	/* Probe point 4 */
+	probepoint |= ((4 << 16) | 0);
+	SDT_PROBE(sctp, cwnd, net, rttvar,
+	    vtag,
+	    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+	    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+	    net->flight_size,
+	    probepoint);
+	if (net->cc_mod.rtcc.steady_step) {
+		oth = net->cc_mod.rtcc.vol_reduce;
+		oth <<= 16;
+		oth |= net->cc_mod.rtcc.step_cnt;
+		oth <<= 16;
+		oth |= net->cc_mod.rtcc.last_step_state;
+		SDT_PROBE(sctp, cwnd, net, rttstep,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    oth,
+		    probepoint);
+		if ((net->cc_mod.rtcc.vol_reduce) &&
+		    (inst_ind != SCTP_INST_GAINING)) {
+			net->cwnd += net->mtu;
+			net->cc_mod.rtcc.vol_reduce--;
+		}
+		net->cc_mod.rtcc.last_step_state = 4;
+		net->cc_mod.rtcc.step_cnt = 0;
+	}
+out_decision:
+	net->cc_mod.rtcc.lbw = nbw;
+	net->cc_mod.rtcc.lbw_rtt = net->rtt;
+	net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
+	if (inst_ind == SCTP_INST_GAINING) {
+		return (1);
+	} else {
+		return (0);
+	}
+}
+
+static int
+cc_bw_increase(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw,
+    uint64_t vtag, uint8_t inst_ind)
+{
+	uint64_t oth, probepoint;
+
+	/*
+	 * BW increased, so update and return 0, since all actions in our
+	 * table say to do the normal CC update. Note that we pay no
+	 * attention to the inst_ind since our overall sum is increasing.
+	 */
+	/* PROBE POINT 0 */
+	probepoint = (((uint64_t) net->cwnd) << 32);
+	SDT_PROBE(sctp, cwnd, net, rttvar,
+	    vtag,
+	    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+	    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+	    net->flight_size,
+	    probepoint);
+	if (net->cc_mod.rtcc.steady_step) {
+		oth = net->cc_mod.rtcc.vol_reduce;
+		oth <<= 16;
+		oth |= net->cc_mod.rtcc.step_cnt;
+		oth <<= 16;
+		oth |= net->cc_mod.rtcc.last_step_state;
+		SDT_PROBE(sctp, cwnd, net, rttstep,
+		    vtag,
+		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    oth,
+		    probepoint);
+		net->cc_mod.rtcc.last_step_state = 0;
+		net->cc_mod.rtcc.step_cnt = 0;
+		net->cc_mod.rtcc.vol_reduce = 0;
+	}
+	net->cc_mod.rtcc.lbw = nbw;
+	net->cc_mod.rtcc.lbw_rtt = net->rtt;
+	net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
+	return (0);
+}
 
 /* RTCC Algoritm to limit growth of cwnd, return
  * true if you want to NOT allow cwnd growth
@@ -193,6 +515,11 @@ static int
 cc_bw_limit(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw)
 {
 	uint64_t bw_offset, rtt_offset, rtt, vtag, probepoint;
+	uint64_t bytes_for_this_rtt, inst_bw;
+	uint64_t div, inst_off;
+	int bw_shift;
+	uint8_t inst_ind;
+	int ret;
 
 	/*-
 	 * Here we need to see if we want
@@ -231,151 +558,67 @@ cc_bw_limit(struct sctp_tcb *stcb, struct sctp_nets *net, uint64_t nbw)
 	 * RTT it stayed the same if it did not
 	 * change within 1/32nd
 	 */
+	bw_shift = SCTP_BASE_SYSCTL(sctp_rttvar_bw);
 	rtt = stcb->asoc.my_vtag;
 	vtag = (rtt << 32) | (((uint32_t) (stcb->sctp_ep->sctp_lport)) << 16) | (stcb->rport);
 	probepoint = (((uint64_t) net->cwnd) << 32);
 	rtt = net->rtt;
-	bw_offset = net->cc_mod.rtcc.lbw >> SCTP_BASE_SYSCTL(sctp_rttvar_bw);
-	if (nbw > net->cc_mod.rtcc.lbw + bw_offset) {
-		/*
-		 * BW increased, so update and return 0, since all actions
-		 * in our table say to do the normal CC update
-		 */
-		/* PROBE POINT 0 */
+	if (net->cc_mod.rtcc.rtt_set_this_sack) {
+		net->cc_mod.rtcc.rtt_set_this_sack = 0;
+		bytes_for_this_rtt = net->cc_mod.rtcc.bw_bytes - net->cc_mod.rtcc.bw_bytes_at_last_rttc;
+		net->cc_mod.rtcc.bw_bytes_at_last_rttc = net->cc_mod.rtcc.bw_bytes;
+		if (net->rtt) {
+			div = net->rtt / 1000;
+			if (div) {
+				inst_bw = bytes_for_this_rtt / div;
+				inst_off = inst_bw >> bw_shift;
+				if (inst_bw > nbw)
+					inst_ind = SCTP_INST_GAINING;
+				else if ((inst_bw + inst_off) < nbw)
+					inst_ind = SCTP_INST_LOOSING;
+				else
+					inst_ind = SCTP_INST_NEUTRAL;
+				probepoint |= ((0xb << 16) | inst_ind);
+			} else {
+				inst_bw = bytes_for_this_rtt / (uint64_t) (net->rtt);
+				/* Can't determine do not change */
+				inst_ind = net->cc_mod.rtcc.last_inst_ind;
+				probepoint |= ((0xc << 16) | inst_ind);
+			}
+		} else {
+			inst_bw = bytes_for_this_rtt;
+			/* Can't determine do not change */
+			inst_ind = net->cc_mod.rtcc.last_inst_ind;
+			probepoint |= ((0xd << 16) | inst_ind);
+		}
 		SDT_PROBE(sctp, cwnd, net, rttvar,
 		    vtag,
-		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-		    net->cc_mod.rtcc.lbw_rtt,
-		    rtt,
+		    ((nbw << 32) | inst_bw),
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | rtt),
+		    net->flight_size,
 		    probepoint);
-		net->cc_mod.rtcc.lbw = nbw;
-		net->cc_mod.rtcc.lbw_rtt = rtt;
-		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
-		return (0);
+	} else {
+		/* No rtt measurement, use last one */
+		inst_ind = net->cc_mod.rtcc.last_inst_ind;
+	}
+	bw_offset = net->cc_mod.rtcc.lbw >> bw_shift;
+	if (nbw > net->cc_mod.rtcc.lbw + bw_offset) {
+		ret = cc_bw_increase(stcb, net, nbw, vtag, inst_ind);
+		goto out;
 	}
 	rtt_offset = net->cc_mod.rtcc.lbw_rtt >> SCTP_BASE_SYSCTL(sctp_rttvar_rtt);
 	if (nbw < net->cc_mod.rtcc.lbw - bw_offset) {
-		/* Bandwidth decreased. */
-		if (rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
-			/* rtt increased */
-			/* Did we add more */
-			if (net->cwnd > net->cc_mod.rtcc.cwnd_at_bw_set) {
-				/* We caused it maybe.. back off */
-				/* PROBE POINT 1 */
-				probepoint |= ((1 << 16) | 1);
-				SDT_PROBE(sctp, cwnd, net, rttvar,
-				    vtag,
-				    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-				    net->cc_mod.rtcc.lbw_rtt,
-				    rtt,
-				    probepoint);
-
-				net->cc_mod.rtcc.lbw = nbw;
-				net->cc_mod.rtcc.lbw_rtt = rtt;
-				net->cwnd = net->cc_mod.rtcc.cwnd_at_bw_set;
-				if (net->cc_mod.rtcc.ret_from_eq) {
-					/*
-					 * Switch over to CA if we are less
-					 * aggressive
-					 */
-					net->ssthresh = net->cwnd - 1;
-					net->partial_bytes_acked = 0;
-				}
-				return (1);
-			}
-			/* Probe point 2 */
-			probepoint |= ((2 << 16) | 0);
-			SDT_PROBE(sctp, cwnd, net, rttvar,
-			    vtag,
-			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-			    net->cc_mod.rtcc.lbw_rtt,
-			    rtt,
-			    probepoint);
-
-			/* Someone else - fight for more? */
-			net->cc_mod.rtcc.lbw = nbw;
-			net->cc_mod.rtcc.lbw_rtt = rtt;
-			net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
-			return (0);
-		} else if (rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
-			/* rtt decreased */
-			/* Probe point 3 */
-			probepoint |= ((3 << 16) | 0);
-			SDT_PROBE(sctp, cwnd, net, rttvar,
-			    vtag,
-			    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-			    net->cc_mod.rtcc.lbw_rtt,
-			    rtt,
-			    probepoint);
-			net->cc_mod.rtcc.lbw = nbw;
-			net->cc_mod.rtcc.lbw_rtt = rtt;
-			net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
-			return (0);
-		}
-		/* The bw decreased but rtt stayed the same */
-		net->cc_mod.rtcc.lbw = nbw;
-		net->cc_mod.rtcc.lbw_rtt = rtt;
-		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
-		/* Probe point 4 */
-		probepoint |= ((4 << 16) | 0);
-		SDT_PROBE(sctp, cwnd, net, rttvar,
-		    vtag,
-		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-		    net->cc_mod.rtcc.lbw_rtt,
-		    rtt,
-		    probepoint);
-		return (0);
+		ret = cc_bw_decrease(stcb, net, nbw, rtt_offset, vtag, inst_ind);
+		goto out;
 	}
 	/*
 	 * If we reach here then we are in a situation where the bw stayed
 	 * the same.
 	 */
-	if (rtt > net->cc_mod.rtcc.lbw_rtt + rtt_offset) {
-		/*
-		 * rtt increased we don't update bw.. so we don't update the
-		 * rtt either.
-		 */
-		/* Probe point 5 */
-		probepoint |= ((5 << 16) | 1);
-		SDT_PROBE(sctp, cwnd, net, rttvar,
-		    vtag,
-		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-		    net->cc_mod.rtcc.lbw_rtt,
-		    rtt,
-		    probepoint);
-		return (1);
-	}
-	if (rtt < net->cc_mod.rtcc.lbw_rtt - rtt_offset) {
-		/*
-		 * rtt decreased, there could be more room. we update both
-		 * the bw and the rtt here.
-		 */
-		/* Probe point 6 */
-		probepoint |= ((6 << 16) | 0);
-		SDT_PROBE(sctp, cwnd, net, rttvar,
-		    vtag,
-		    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-		    net->cc_mod.rtcc.lbw_rtt,
-		    rtt,
-		    probepoint);
-		net->cc_mod.rtcc.lbw = nbw;
-		net->cc_mod.rtcc.lbw_rtt = rtt;
-		net->cc_mod.rtcc.cwnd_at_bw_set = net->cwnd;
-		return (0);
-	}
-	/*
-	 * Ok bw and rtt remained the same .. no update to any but save the
-	 * latest cwnd.
-	 */
-	/* Probe point 7 */
-	probepoint |= ((7 << 16) | net->cc_mod.rtcc.ret_from_eq);
-	SDT_PROBE(sctp, cwnd, net, rttvar,
-	    vtag,
-	    ((net->cc_mod.rtcc.lbw << 32) | nbw),
-	    net->cc_mod.rtcc.lbw_rtt,
-	    rtt,
-	    probepoint);
-	return ((int)net->cc_mod.rtcc.ret_from_eq);
+	ret = cc_bw_same(stcb, net, nbw, rtt_offset, vtag, inst_ind);
+out:
+	net->cc_mod.rtcc.last_inst_ind = inst_ind;
+	return (ret);
 }
 
 static void
@@ -554,11 +797,15 @@ sctp_cwnd_update_after_sack_common(struct sctp_tcb *stcb,
 				SDT_PROBE(sctp, cwnd, net, rttvar,
 				    vtag,
 				    nbw,
-				    0,
-				    net->rtt,
+				    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+				    net->flight_size,
 				    probepoint);
 				net->cc_mod.rtcc.lbw = nbw;
 				net->cc_mod.rtcc.lbw_rtt = net->rtt;
+				if (net->cc_mod.rtcc.rtt_set_this_sack) {
+					net->cc_mod.rtcc.rtt_set_this_sack = 0;
+					net->cc_mod.rtcc.bw_bytes_at_last_rttc = net->cc_mod.rtcc.bw_bytes;
+				}
 			}
 		}
 		/*
@@ -1014,15 +1261,22 @@ sctp_cwnd_new_rtcc_transmission_begins(struct sctp_tcb *stcb,
 		SDT_PROBE(sctp, cwnd, net, rttvar,
 		    vtag,
 		    ((net->cc_mod.rtcc.lbw << 32) | 0),
-		    net->cc_mod.rtcc.lbw_rtt,
-		    0,
+		    ((net->cc_mod.rtcc.lbw_rtt << 32) | net->rtt),
+		    net->flight_size,
 		    probepoint);
 		net->cc_mod.rtcc.lbw_rtt = 0;
 		net->cc_mod.rtcc.cwnd_at_bw_set = 0;
 		net->cc_mod.rtcc.lbw = 0;
+		net->cc_mod.rtcc.bw_bytes_at_last_rttc = 0;
+		net->cc_mod.rtcc.vol_reduce = 0;
 		net->cc_mod.rtcc.bw_tot_time = 0;
 		net->cc_mod.rtcc.bw_bytes = 0;
 		net->cc_mod.rtcc.tls_needs_set = 0;
+		if (net->cc_mod.rtcc.steady_step) {
+			net->cc_mod.rtcc.vol_reduce = 0;
+			net->cc_mod.rtcc.step_cnt = 0;
+			net->cc_mod.rtcc.last_step_state = 0;
+		}
 		if (net->cc_mod.rtcc.ret_from_eq) {
 			/* less aggressive one - reset cwnd too */
 			uint32_t cwnd_in_mtu, cwnd;
@@ -1075,11 +1329,20 @@ sctp_set_rtcc_initial_cc_param(struct sctp_tcb *stcb,
 	    probepoint);
 	net->cc_mod.rtcc.lbw_rtt = 0;
 	net->cc_mod.rtcc.cwnd_at_bw_set = 0;
+	net->cc_mod.rtcc.vol_reduce = 0;
 	net->cc_mod.rtcc.lbw = 0;
+	net->cc_mod.rtcc.vol_reduce = 0;
+	net->cc_mod.rtcc.bw_bytes_at_last_rttc = 0;
 	net->cc_mod.rtcc.bw_tot_time = 0;
 	net->cc_mod.rtcc.bw_bytes = 0;
 	net->cc_mod.rtcc.tls_needs_set = 0;
 	net->cc_mod.rtcc.ret_from_eq = SCTP_BASE_SYSCTL(sctp_rttvar_eqret);
+	net->cc_mod.rtcc.steady_step = SCTP_BASE_SYSCTL(sctp_steady_step);
+	net->cc_mod.rtcc.use_dccc_ecn = SCTP_BASE_SYSCTL(sctp_use_dccc_ecn);
+	net->cc_mod.rtcc.step_cnt = 0;
+	net->cc_mod.rtcc.last_step_state = 0;
+
+
 }
 
 static int
@@ -1106,6 +1369,10 @@ sctp_cwnd_rtcc_socket_option(struct sctp_tcb *stcb, int setorget,
 			TAILQ_FOREACH(net, &stcb->asoc.nets, sctp_next) {
 				net->cc_mod.rtcc.use_dccc_ecn = cc_opt->aid_value.assoc_value;
 			}
+		} else if (cc_opt->option == SCTP_CC_OPT_STEADY_STEP) {
+			TAILQ_FOREACH(net, &stcb->asoc.nets, sctp_next) {
+				net->cc_mod.rtcc.steady_step = cc_opt->aid_value.assoc_value;
+			}
 		} else {
 			return (EINVAL);
 		}
@@ -1123,6 +1390,12 @@ sctp_cwnd_rtcc_socket_option(struct sctp_tcb *stcb, int setorget,
 				return (EFAULT);
 			}
 			cc_opt->aid_value.assoc_value = net->cc_mod.rtcc.use_dccc_ecn;
+		} else if (cc_opt->option == SCTP_CC_OPT_STEADY_STEP) {
+			net = TAILQ_FIRST(&stcb->asoc.nets);
+			if (net == NULL) {
+				return (EFAULT);
+			}
+			cc_opt->aid_value.assoc_value = net->cc_mod.rtcc.steady_step;
 		} else {
 			return (EINVAL);
 		}
@@ -1149,6 +1422,12 @@ sctp_cwnd_update_rtcc_after_sack(struct sctp_tcb *stcb,
 	sctp_cwnd_update_after_sack_common(stcb, asoc, accum_moved, reneged_all, will_exit, 1);
 }
 
+static void
+sctp_rtt_rtcc_calculated(struct sctp_tcb *stcb,
+    struct sctp_nets *net, struct timeval *now)
+{
+	net->cc_mod.rtcc.rtt_set_this_sack = 1;
+}
 
 /* Here starts Sally Floyds HS-TCP */
 
@@ -2203,6 +2482,7 @@ struct sctp_cc_functions sctp_cc_functions[] = {
 		.sctp_cwnd_update_tsn_acknowledged = sctp_cwnd_update_rtcc_tsn_acknowledged,
 		.sctp_cwnd_new_transmission_begins = sctp_cwnd_new_rtcc_transmission_begins,
 		.sctp_cwnd_prepare_net_for_sack = sctp_cwnd_prepare_rtcc_net_for_sack,
-		.sctp_cwnd_socket_option = sctp_cwnd_rtcc_socket_option
+		.sctp_cwnd_socket_option = sctp_cwnd_rtcc_socket_option,
+		.sctp_rtt_calculated = sctp_rtt_rtcc_calculated
 	}
 };
diff --git a/sys/netinet/sctp_constants.h b/sys/netinet/sctp_constants.h
index 85c92ed4d58..6c2df1693fb 100644
--- a/sys/netinet/sctp_constants.h
+++ b/sys/netinet/sctp_constants.h
@@ -355,8 +355,8 @@ __FBSDID("$FreeBSD$");
 /* RTO calculation flag to say if it
  * is safe to determine local lan or not.
  */
-#define SCTP_DETERMINE_LL_NOTOK 0
-#define SCTP_DETERMINE_LL_OK    1
+#define SCTP_RTT_FROM_NON_DATA 0
+#define SCTP_RTT_FROM_DATA     1
 
 
 /* IP hdr (20/40) + 12+2+2 (enet) + sctp common 12 */
diff --git a/sys/netinet/sctp_dtrace_declare.h b/sys/netinet/sctp_dtrace_declare.h
index 7279f66b77f..6f0f8b10aac 100644
--- a/sys/netinet/sctp_dtrace_declare.h
+++ b/sys/netinet/sctp_dtrace_declare.h
@@ -57,6 +57,7 @@ SDT_PROBE_DECLARE(sctp, cwnd, net, ecn);
 SDT_PROBE_DECLARE(sctp, cwnd, net, pd);
 /* Rttvar probe declaration */
 SDT_PROBE_DECLARE(sctp, cwnd, net, rttvar);
+SDT_PROBE_DECLARE(sctp, cwnd, net, rttstep);
 
 /* One to track an associations rwnd */
 SDT_PROBE_DECLARE(sctp, rwnd, assoc, val);
diff --git a/sys/netinet/sctp_dtrace_define.h b/sys/netinet/sctp_dtrace_define.h
index f773cf105a7..5f7bf14db14 100644
--- a/sys/netinet/sctp_dtrace_define.h
+++ b/sys/netinet/sctp_dtrace_define.h
@@ -78,14 +78,27 @@ SDT_PROBE_DEFINE(sctp, cwnd, net, rttvar, rttvar);
 SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttvar, 0, "uint64_t");
 /* obw | nbw */
 SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttvar, 1, "uint64_t");
-/* newrtt */
+/* bwrtt | newrtt */
 SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttvar, 2, "uint64_t");
-/* bwrtt  */
+/* flight */
 SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttvar, 3, "uint64_t");
 /* (cwnd << 32) | point << 16 | retval(0/1) */
 SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttvar, 4, "uint64_t");
 
 
+SDT_PROBE_DEFINE(sctp, cwnd, net, rttstep, rttstep);
+/* The Vtag << 32 | localport << 16 | remoteport */
+SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttstep, 0, "uint64_t");
+/* obw | nbw */
+SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttstep, 1, "uint64_t");
+/* bwrtt | nrtt */
+SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttstep, 2, "uint64_t");
+/* cwnd_saved | stepcnt << 16 | oldstep  */
+SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttstep, 3, "uint64_t");
+/* (cwnd << 32) | point << 16 | retval(0/1) */
+SDT_PROBE_ARGTYPE(sctp, cwnd, net, rttstep, 4, "uint64_t");
+
+
 /* FastRetransmit-DECREASE */
 SDT_PROBE_DEFINE(sctp, cwnd, net, fr, fr);
 /* The Vtag for this end */
diff --git a/sys/netinet/sctp_indata.c b/sys/netinet/sctp_indata.c
index 1ec465e63a7..6ea4669670f 100644
--- a/sys/netinet/sctp_indata.c
+++ b/sys/netinet/sctp_indata.c
@@ -2817,7 +2817,7 @@ sctp_process_segment_range(struct sctp_tcb *stcb, struct sctp_tmit_chunk **p_tp1
     int *num_frs,
     uint32_t * biggest_newly_acked_tsn,
     uint32_t * this_sack_lowest_newack,
-    int *ecn_seg_sums)
+    int *ecn_seg_sums, int *rto_ok)
 {
 	struct sctp_tmit_chunk *tp1;
 	unsigned int theTSN;
@@ -2956,13 +2956,19 @@ sctp_process_segment_range(struct sctp_tcb *stcb, struct sctp_tmit_chunk **p_tp1
 							 * update RTO too ?
 							 */
 							if (tp1->do_rtt) {
-								tp1->whoTo->RTO =
-								    sctp_calculate_rto(stcb,
-								    &stcb->asoc,
-								    tp1->whoTo,
-								    &tp1->sent_rcv_time,
-								    sctp_align_safe_nocopy,
-								    SCTP_DETERMINE_LL_OK);
+								if (*rto_ok) {
+									tp1->whoTo->RTO =
+									    sctp_calculate_rto(stcb,
+									    &stcb->asoc,
+									    tp1->whoTo,
+									    &tp1->sent_rcv_time,
+									    sctp_align_safe_nocopy,
+									    SCTP_RTT_FROM_DATA);
+									*rto_ok = 0;
+								}
+								if (tp1->whoTo->rto_needed == 0) {
+									tp1->whoTo->rto_needed = 1;
+								}
 								tp1->do_rtt = 0;
 							}
 						}
@@ -3033,7 +3039,8 @@ static int
 sctp_handle_segments(struct mbuf *m, int *offset, struct sctp_tcb *stcb, struct sctp_association *asoc,
     uint32_t last_tsn, uint32_t * biggest_tsn_acked,
     uint32_t * biggest_newly_acked_tsn, uint32_t * this_sack_lowest_newack,
-    int num_seg, int num_nr_seg, int *ecn_seg_sums)
+    int num_seg, int num_nr_seg, int *ecn_seg_sums,
+    int *rto_ok)
 {
 	struct sctp_gap_ack_block *frag, block;
 	struct sctp_tmit_chunk *tp1;
@@ -3079,7 +3086,7 @@ sctp_handle_segments(struct mbuf *m, int *offset, struct sctp_tcb *stcb, struct
 		}
 		if (sctp_process_segment_range(stcb, &tp1, last_tsn, frag_strt, frag_end,
 		    non_revocable, &num_frs, biggest_newly_acked_tsn,
-		    this_sack_lowest_newack, ecn_seg_sums)) {
+		    this_sack_lowest_newack, ecn_seg_sums, rto_ok)) {
 			chunk_freed = 1;
 		}
 		prev_frag_end = frag_end;
@@ -3579,6 +3586,9 @@ sctp_strike_gap_ack_chunks(struct sctp_tcb *stcb, struct sctp_association *asoc,
 				 * this guy had a RTO calculation pending on
 				 * it, cancel it
 				 */
+				if (tp1->whoTo->rto_needed == 0) {
+					tp1->whoTo->rto_needed = 1;
+				}
 				tp1->do_rtt = 0;
 			}
 			if (alt != tp1->whoTo) {
@@ -3775,6 +3785,7 @@ sctp_express_handle_sack(struct sctp_tcb *stcb, uint32_t cumack,
 	int win_probe_recovery = 0;
 	int win_probe_recovered = 0;
 	int j, done_once = 0;
+	int rto_ok = 1;
 
 	if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_LOG_SACK_ARRIVALS_ENABLE) {
 		sctp_misc_ints(SCTP_SACK_LOG_EXPRESS, cumack,
@@ -3916,16 +3927,23 @@ sctp_express_handle_sack(struct sctp_tcb *stcb, uint32_t cumack,
 
 						/* update RTO too? */
 						if (tp1->do_rtt) {
-							tp1->whoTo->RTO =
-							/*
-							 * sa_ignore
-							 * NO_NULL_CHK
-							 */
-							    sctp_calculate_rto(stcb,
-							    asoc, tp1->whoTo,
-							    &tp1->sent_rcv_time,
-							    sctp_align_safe_nocopy,
-							    SCTP_DETERMINE_LL_OK);
+							if (rto_ok) {
+								tp1->whoTo->RTO =
+								/*
+								 * sa_ignore
+								 * NO_NULL_CH
+								 * K
+								 */
+								    sctp_calculate_rto(stcb,
+								    asoc, tp1->whoTo,
+								    &tp1->sent_rcv_time,
+								    sctp_align_safe_nocopy,
+								    SCTP_RTT_FROM_DATA);
+								rto_ok = 0;
+							}
+							if (tp1->whoTo->rto_needed == 0) {
+								tp1->whoTo->rto_needed = 1;
+							}
 							tp1->do_rtt = 0;
 						}
 					}
@@ -4280,6 +4298,7 @@ sctp_handle_sack(struct mbuf *m, int offset_seg, int offset_dup,
 	struct sctp_nets *net = NULL;
 	int ecn_seg_sums = 0;
 	int done_once;
+	int rto_ok = 1;
 	uint8_t reneged_all = 0;
 	uint8_t cmt_dac_flag;
 
@@ -4526,12 +4545,18 @@ sctp_handle_sack(struct mbuf *m, int offset_seg, int offset_dup,
 
 						/* update RTO too? */
 						if (tp1->do_rtt) {
-							tp1->whoTo->RTO =
-							    sctp_calculate_rto(stcb,
-							    asoc, tp1->whoTo,
-							    &tp1->sent_rcv_time,
-							    sctp_align_safe_nocopy,
-							    SCTP_DETERMINE_LL_OK);
+							if (rto_ok) {
+								tp1->whoTo->RTO =
+								    sctp_calculate_rto(stcb,
+								    asoc, tp1->whoTo,
+								    &tp1->sent_rcv_time,
+								    sctp_align_safe_nocopy,
+								    SCTP_RTT_FROM_DATA);
+								rto_ok = 0;
+							}
+							if (tp1->whoTo->rto_needed == 0) {
+								tp1->whoTo->rto_needed = 1;
+							}
 							tp1->do_rtt = 0;
 						}
 					}
@@ -4606,7 +4631,8 @@ sctp_handle_sack(struct mbuf *m, int offset_seg, int offset_dup,
 		 */
 		if (sctp_handle_segments(m, &offset_seg, stcb, asoc, last_tsn, &biggest_tsn_acked,
 		    &biggest_tsn_newly_acked, &this_sack_lowest_newack,
-		    num_seg, num_nr_seg, &ecn_seg_sums)) {
+		    num_seg, num_nr_seg, &ecn_seg_sums,
+		    &rto_ok)) {
 			wake_him++;
 		}
 		if (SCTP_BASE_SYSCTL(sctp_strict_sacks)) {
diff --git a/sys/netinet/sctp_input.c b/sys/netinet/sctp_input.c
index 1329c40e52d..3c25eaabf29 100644
--- a/sys/netinet/sctp_input.c
+++ b/sys/netinet/sctp_input.c
@@ -485,7 +485,7 @@ sctp_process_init_ack(struct mbuf *m, int iphlen, int offset,
 
 	/* calculate the RTO */
 	net->RTO = sctp_calculate_rto(stcb, asoc, net, &asoc->time_entered, sctp_align_safe_nocopy,
-	    SCTP_DETERMINE_LL_NOTOK);
+	    SCTP_RTT_FROM_NON_DATA);
 
 	retval = sctp_send_cookie_echo(m, offset, stcb, net);
 	if (retval < 0) {
@@ -630,7 +630,7 @@ sctp_handle_heartbeat_ack(struct sctp_heartbeat_chunk *cp,
 	}
 	/* Now lets do a RTO with this */
 	r_net->RTO = sctp_calculate_rto(stcb, &stcb->asoc, r_net, &tv, sctp_align_safe_nocopy,
-	    SCTP_DETERMINE_LL_OK);
+	    SCTP_RTT_FROM_NON_DATA);
 	/* Mobility adaptation */
 	if (req_prim) {
 		if ((sctp_is_mobility_feature_on(stcb->sctp_ep,
@@ -1547,7 +1547,7 @@ sctp_process_cookie_existing(struct mbuf *m, int iphlen, int offset,
 			net->RTO = sctp_calculate_rto(stcb, asoc, net,
 			    &cookie->time_entered,
 			    sctp_align_unsafe_makecopy,
-			    SCTP_DETERMINE_LL_NOTOK);
+			    SCTP_RTT_FROM_NON_DATA);
 
 			if (stcb->asoc.sctp_autoclose_ticks &&
 			    (sctp_is_feature_on(inp, SCTP_PCB_FLAGS_AUTOCLOSE))) {
@@ -2251,7 +2251,7 @@ sctp_process_cookie_new(struct mbuf *m, int iphlen, int offset,
 	if ((netp) && (*netp)) {
 		(*netp)->RTO = sctp_calculate_rto(stcb, asoc, *netp,
 		    &cookie->time_entered, sctp_align_unsafe_makecopy,
-		    SCTP_DETERMINE_LL_NOTOK);
+		    SCTP_RTT_FROM_NON_DATA);
 	}
 	/* respond with a COOKIE-ACK */
 	sctp_send_cookie_ack(stcb);
@@ -2849,7 +2849,7 @@ sctp_handle_cookie_ack(struct sctp_cookie_ack_chunk *cp,
 		if (asoc->overall_error_count == 0) {
 			net->RTO = sctp_calculate_rto(stcb, asoc, net,
 			    &asoc->time_entered, sctp_align_safe_nocopy,
-			    SCTP_DETERMINE_LL_NOTOK);
+			    SCTP_RTT_FROM_NON_DATA);
 		}
 		(void)SCTP_GETTIME_TIMEVAL(&asoc->time_entered);
 		sctp_ulp_notify(SCTP_NOTIFY_ASSOC_UP, stcb, 0, NULL, SCTP_SO_NOT_LOCKED);
@@ -3218,6 +3218,9 @@ process_chunk_drop(struct sctp_tcb *stcb, struct sctp_chunk_desc *desc,
 					 * this guy had a RTO calculation
 					 * pending on it, cancel it
 					 */
+					if (tp1->whoTo->rto_needed == 0) {
+						tp1->whoTo->rto_needed = 1;
+					}
 					tp1->do_rtt = 0;
 				}
 				SCTP_STAT_INCR(sctps_pdrpmark);
diff --git a/sys/netinet/sctp_output.c b/sys/netinet/sctp_output.c
index 1fe48477cc7..23361baf57a 100644
--- a/sys/netinet/sctp_output.c
+++ b/sys/netinet/sctp_output.c
@@ -8254,7 +8254,10 @@ no_data_fill:
 				} else {
 					asoc->time_last_sent = *now;
 				}
-				data_list[0]->do_rtt = 1;
+				if (net->rto_needed) {
+					data_list[0]->do_rtt = 1;
+					net->rto_needed = 0;
+				}
 				SCTP_STAT_INCR_BY(sctps_senddata, bundle_at);
 				sctp_clean_up_datalist(stcb, asoc, data_list, bundle_at, net);
 				if (SCTP_BASE_SYSCTL(sctp_early_fr)) {
diff --git a/sys/netinet/sctp_pcb.c b/sys/netinet/sctp_pcb.c
index a6acbeea634..79781614719 100644
--- a/sys/netinet/sctp_pcb.c
+++ b/sys/netinet/sctp_pcb.c
@@ -3858,6 +3858,7 @@ sctp_add_remote_addr(struct sctp_tcb *stcb, struct sockaddr *newaddr,
 	 * We set this to 0, the timer code knows that this means its an
 	 * initial value
 	 */
+	net->rto_needed = 1;
 	net->RTO = 0;
 	net->RTO_measured = 0;
 	stcb->asoc.numnets++;
diff --git a/sys/netinet/sctp_structs.h b/sys/netinet/sctp_structs.h
index 39b7572be0d..250b312f3d7 100644
--- a/sys/netinet/sctp_structs.h
+++ b/sys/netinet/sctp_structs.h
@@ -226,11 +226,20 @@ struct rtcc_cc {
 	uint64_t bw_bytes;	/* The total bytes since this sending began */
 	uint64_t bw_tot_time;	/* The total time since sending began */
 	uint64_t new_tot_time;	/* temp holding the new value */
-	uint32_t cwnd_at_bw_set;
-	uint8_t ret_from_eq;
-	uint8_t use_dccc_ecn;
+	uint64_t bw_bytes_at_last_rttc;	/* What bw_bytes was at last rtt calc */
+	uint32_t cwnd_at_bw_set;/* Cwnd at last bw saved - lbw */
+	uint32_t vol_reduce;	/* cnt of voluntary reductions */
+	uint16_t steady_step;	/* The number required to be in steady state */
+	uint16_t step_cnt;	/* The current number */
+	uint8_t ret_from_eq;	/* When all things are equal what do I return
+				 * 0/1 - 1 no cc advance */
+	uint8_t use_dccc_ecn;	/* Flag to enable DCCC ECN */
 	uint8_t tls_needs_set;	/* Flag to indicate we need to set tls 0 or 1
 				 * means set at send 2 not */
+	uint8_t last_step_state;/* Last state if steady state stepdown is on */
+	uint8_t rtt_set_this_sack;	/* Flag saying this sack had RTT calc
+					 * on it */
+	uint8_t last_inst_ind;	/* Last saved inst indication */
 };
 
 
@@ -364,6 +373,7 @@ struct sctp_nets {
 	uint8_t RTO_measured;	/* Have we done the first measure */
 	uint8_t last_hs_used;	/* index into the last HS table entry we used */
 	uint8_t lan_type;
+	uint8_t rto_needed;
 	uint32_t flowid;
 #ifdef INVARIANTS
 	uint8_t flowidset;
@@ -671,6 +681,7 @@ struct sctp_cc_functions {
 	void (*sctp_cwnd_prepare_net_for_sack) (struct sctp_tcb *stcb,
 	         struct sctp_nets *net);
 	int (*sctp_cwnd_socket_option) (struct sctp_tcb *stcb, int set, struct sctp_cc_option *);
+	void (*sctp_rtt_calculated) (struct sctp_tcb *, struct sctp_nets *, struct timeval *);
 };
 
 /*
diff --git a/sys/netinet/sctp_sysctl.c b/sys/netinet/sctp_sysctl.c
index 4e69e1f6438..a8d080aaaaf 100644
--- a/sys/netinet/sctp_sysctl.c
+++ b/sys/netinet/sctp_sysctl.c
@@ -118,6 +118,9 @@ sctp_init_sysctls()
 	SCTP_BASE_SYSCTL(sctp_rttvar_bw) = SCTPCTL_RTTVAR_BW_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_rttvar_rtt) = SCTPCTL_RTTVAR_RTT_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_rttvar_eqret) = SCTPCTL_RTTVAR_EQRET_DEFAULT;
+	SCTP_BASE_SYSCTL(sctp_steady_step) = SCTPCTL_RTTVAR_STEADYS_DEFAULT;
+	SCTP_BASE_SYSCTL(sctp_use_dccc_ecn) = SCTPCTL_RTTVAR_DCCCECN_DEFAULT;
+
 #if defined(SCTP_LOCAL_TRACE_BUF)
 	memset(&SCTP_BASE_SYSCTL(sctp_log), 0, sizeof(struct sctp_log));
 #endif
@@ -639,6 +642,8 @@ sysctl_sctp_check(SYSCTL_HANDLER_ARGS)
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_rttvar_bw), SCTPCTL_RTTVAR_BW_MIN, SCTPCTL_RTTVAR_BW_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_rttvar_rtt), SCTPCTL_RTTVAR_RTT_MIN, SCTPCTL_RTTVAR_RTT_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_rttvar_eqret), SCTPCTL_RTTVAR_EQRET_MIN, SCTPCTL_RTTVAR_EQRET_MAX);
+		RANGECHK(SCTP_BASE_SYSCTL(sctp_steady_step), SCTPCTL_RTTVAR_STEADYS_MIN, SCTPCTL_RTTVAR_STEADYS_MAX);
+		RANGECHK(SCTP_BASE_SYSCTL(sctp_use_dccc_ecn), SCTPCTL_RTTVAR_DCCCECN_MIN, SCTPCTL_RTTVAR_DCCCECN_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_mobility_base), SCTPCTL_MOBILITY_BASE_MIN, SCTPCTL_MOBILITY_BASE_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_mobility_fasthandoff), SCTPCTL_MOBILITY_FASTHANDOFF_MIN, SCTPCTL_MOBILITY_FASTHANDOFF_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_udp_tunneling_for_client_enable), SCTPCTL_UDP_TUNNELING_FOR_CLIENT_ENABLE_MIN, SCTPCTL_UDP_TUNNELING_FOR_CLIENT_ENABLE_MAX);
@@ -1118,6 +1123,14 @@ SYSCTL_VNET_PROC(_net_inet_sctp, OID_AUTO, rttvar_eqret, CTLTYPE_UINT | CTLFLAG_
     &SCTP_BASE_SYSCTL(sctp_rttvar_eqret), 0, sysctl_sctp_check, "IU",
     SCTPCTL_RTTVAR_EQRET_DESC);
 
+SYSCTL_VNET_PROC(_net_inet_sctp, OID_AUTO, rttvar_steady_step, CTLTYPE_UINT | CTLFLAG_RW,
+    &SCTP_BASE_SYSCTL(sctp_steady_step), 0, sysctl_sctp_check, "IU",
+    SCTPCTL_RTTVAR_STEADYS_DESC);
+
+SYSCTL_VNET_PROC(_net_inet_sctp, OID_AUTO, use_dcccecn, CTLTYPE_UINT | CTLFLAG_RW,
+    &SCTP_BASE_SYSCTL(sctp_use_dccc_ecn), 0, sysctl_sctp_check, "IU",
+    SCTPCTL_RTTVAR_DCCCECN_DESC);
+
 #ifdef SCTP_DEBUG
 SYSCTL_VNET_PROC(_net_inet_sctp, OID_AUTO, debug, CTLTYPE_UINT | CTLFLAG_RW,
     &SCTP_BASE_SYSCTL(sctp_debug_on), 0, sysctl_sctp_check, "IU",
diff --git a/sys/netinet/sctp_sysctl.h b/sys/netinet/sctp_sysctl.h
index aba691806d8..842d9b1b5f1 100644
--- a/sys/netinet/sctp_sysctl.h
+++ b/sys/netinet/sctp_sysctl.h
@@ -107,6 +107,8 @@ struct sctp_sysctl {
 	uint32_t sctp_rttvar_bw;
 	uint32_t sctp_rttvar_rtt;
 	uint32_t sctp_rttvar_eqret;
+	uint32_t sctp_steady_step;
+	uint32_t sctp_use_dccc_ecn;
 #if defined(SCTP_LOCAL_TRACE_BUF)
 	struct sctp_log sctp_log;
 #endif
@@ -224,8 +226,8 @@ struct sctp_sysctl {
 #define SCTPCTL_CHUNKSCALE_MAX		0xFFFFFFFF
 #define SCTPCTL_CHUNKSCALE_DEFAULT	SCTP_CHUNKQUEUE_SCALE
 
-/* delayed_sack_time: Default delayed SACK timer in msec */
-#define SCTPCTL_DELAYED_SACK_TIME_DESC	"Default delayed SACK timer in msec"
+/* delayed_sack_time: Default delayed SACK timer in ms */
+#define SCTPCTL_DELAYED_SACK_TIME_DESC	"Default delayed SACK timer in ms"
 #define SCTPCTL_DELAYED_SACK_TIME_MIN	0
 #define SCTPCTL_DELAYED_SACK_TIME_MAX	0xFFFFFFFF
 #define SCTPCTL_DELAYED_SACK_TIME_DEFAULT	SCTP_RECV_MSEC
@@ -248,56 +250,56 @@ struct sctp_sysctl {
 #define SCTPCTL_ASOC_RESOURCE_MAX	0xFFFFFFFF
 #define SCTPCTL_ASOC_RESOURCE_DEFAULT	SCTP_DEF_ASOC_RESC_LIMIT
 
-/* heartbeat_interval: Default heartbeat interval in msec */
-#define SCTPCTL_HEARTBEAT_INTERVAL_DESC	"Default heartbeat interval in msec"
+/* heartbeat_interval: Default heartbeat interval in ms */
+#define SCTPCTL_HEARTBEAT_INTERVAL_DESC	"Default heartbeat interval in ms"
 #define SCTPCTL_HEARTBEAT_INTERVAL_MIN	0
 #define SCTPCTL_HEARTBEAT_INTERVAL_MAX	0xFFFFFFFF
 #define SCTPCTL_HEARTBEAT_INTERVAL_DEFAULT	SCTP_HB_DEFAULT_MSEC
 
-/* pmtu_raise_time: Default PMTU raise timer in sec */
-#define SCTPCTL_PMTU_RAISE_TIME_DESC	"Default PMTU raise timer in sec"
+/* pmtu_raise_time: Default PMTU raise timer in seconds */
+#define SCTPCTL_PMTU_RAISE_TIME_DESC	"Default PMTU raise timer in seconds"
 #define SCTPCTL_PMTU_RAISE_TIME_MIN	0
 #define SCTPCTL_PMTU_RAISE_TIME_MAX	0xFFFFFFFF
 #define SCTPCTL_PMTU_RAISE_TIME_DEFAULT	SCTP_DEF_PMTU_RAISE_SEC
 
-/* shutdown_guard_time: Default shutdown guard timer in sec */
-#define SCTPCTL_SHUTDOWN_GUARD_TIME_DESC	"Default shutdown guard timer in sec"
+/* shutdown_guard_time: Default shutdown guard timer in seconds */
+#define SCTPCTL_SHUTDOWN_GUARD_TIME_DESC	"Default shutdown guard timer in seconds"
 #define SCTPCTL_SHUTDOWN_GUARD_TIME_MIN		0
 #define SCTPCTL_SHUTDOWN_GUARD_TIME_MAX		0xFFFFFFFF
 #define SCTPCTL_SHUTDOWN_GUARD_TIME_DEFAULT	SCTP_DEF_MAX_SHUTDOWN_SEC
 
-/* secret_lifetime: Default secret lifetime in sec */
-#define SCTPCTL_SECRET_LIFETIME_DESC	"Default secret lifetime in sec"
+/* secret_lifetime: Default secret lifetime in seconds */
+#define SCTPCTL_SECRET_LIFETIME_DESC	"Default secret lifetime in seconds"
 #define SCTPCTL_SECRET_LIFETIME_MIN	0
 #define SCTPCTL_SECRET_LIFETIME_MAX	0xFFFFFFFF
 #define SCTPCTL_SECRET_LIFETIME_DEFAULT	SCTP_DEFAULT_SECRET_LIFE_SEC
 
-/* rto_max: Default maximum retransmission timeout in msec */
-#define SCTPCTL_RTO_MAX_DESC		"Default maximum retransmission timeout in msec"
+/* rto_max: Default maximum retransmission timeout in ms */
+#define SCTPCTL_RTO_MAX_DESC		"Default maximum retransmission timeout in ms"
 #define SCTPCTL_RTO_MAX_MIN		0
 #define SCTPCTL_RTO_MAX_MAX		0xFFFFFFFF
 #define SCTPCTL_RTO_MAX_DEFAULT		SCTP_RTO_UPPER_BOUND
 
-/* rto_min: Default minimum retransmission timeout in msec */
-#define SCTPCTL_RTO_MIN_DESC		"Default minimum retransmission timeout in msec"
+/* rto_min: Default minimum retransmission timeout in ms */
+#define SCTPCTL_RTO_MIN_DESC		"Default minimum retransmission timeout in ms"
 #define SCTPCTL_RTO_MIN_MIN		0
 #define SCTPCTL_RTO_MIN_MAX		0xFFFFFFFF
 #define SCTPCTL_RTO_MIN_DEFAULT		SCTP_RTO_LOWER_BOUND
 
-/* rto_initial: Default initial retransmission timeout in msec */
-#define SCTPCTL_RTO_INITIAL_DESC	"Default initial retransmission timeout in msec"
+/* rto_initial: Default initial retransmission timeout in ms */
+#define SCTPCTL_RTO_INITIAL_DESC	"Default initial retransmission timeout in ms"
 #define SCTPCTL_RTO_INITIAL_MIN		0
 #define SCTPCTL_RTO_INITIAL_MAX		0xFFFFFFFF
 #define SCTPCTL_RTO_INITIAL_DEFAULT	SCTP_RTO_INITIAL
 
-/* init_rto_max: Default maximum retransmission timeout during association setup in msec */
-#define SCTPCTL_INIT_RTO_MAX_DESC	"Default maximum retransmission timeout during association setup in msec"
+/* init_rto_max: Default maximum retransmission timeout during association setup in ms */
+#define SCTPCTL_INIT_RTO_MAX_DESC	"Default maximum retransmission timeout during association setup in ms"
 #define SCTPCTL_INIT_RTO_MAX_MIN	0
 #define SCTPCTL_INIT_RTO_MAX_MAX	0xFFFFFFFF
 #define SCTPCTL_INIT_RTO_MAX_DEFAULT	SCTP_RTO_UPPER_BOUND
 
 /* valid_cookie_life: Default cookie lifetime in sec */
-#define SCTPCTL_VALID_COOKIE_LIFE_DESC	"Default cookie lifetime in sec"
+#define SCTPCTL_VALID_COOKIE_LIFE_DESC	"Default cookie lifetime in seconds"
 #define SCTPCTL_VALID_COOKIE_LIFE_MIN	0
 #define SCTPCTL_VALID_COOKIE_LIFE_MAX	0xFFFFFFFF
 #define SCTPCTL_VALID_COOKIE_LIFE_DEFAULT	SCTP_DEFAULT_COOKIE_LIFE
@@ -320,8 +322,8 @@ struct sctp_sysctl {
 #define SCTPCTL_PATH_RTX_MAX_MAX	0xFFFFFFFF
 #define SCTPCTL_PATH_RTX_MAX_DEFAULT	SCTP_DEF_MAX_PATH_RTX
 
-/* add_more_on_output: When space wise is it worthwhile to try to add more to a socket send buffer */
-#define SCTPCTL_ADD_MORE_ON_OUTPUT_DESC	"When space wise is it worthwhile to try to add more to a socket send buffer"
+/* add_more_on_output: When space-wise is it worthwhile to try to add more to a socket send buffer */
+#define SCTPCTL_ADD_MORE_ON_OUTPUT_DESC	"When space-wise is it worthwhile to try to add more to a socket send buffer"
 #define SCTPCTL_ADD_MORE_ON_OUTPUT_MIN	0
 #define SCTPCTL_ADD_MORE_ON_OUTPUT_MAX	0xFFFFFFFF
 #define SCTPCTL_ADD_MORE_ON_OUTPUT_DEFAULT SCTP_DEFAULT_ADD_MORE
@@ -519,22 +521,32 @@ struct sctp_sysctl {
 #define SCTPCTL_INITIAL_CWND_DEFAULT	3
 
 /* rttvar smooth avg for bw calc  */
-#define SCTPCTL_RTTVAR_BW_DESC	"Shift amount for bw smothing on rtt calc"
+#define SCTPCTL_RTTVAR_BW_DESC	"Shift amount for bw smoothing on rtt calc"
 #define SCTPCTL_RTTVAR_BW_MIN	0
 #define SCTPCTL_RTTVAR_BW_MAX	32
 #define SCTPCTL_RTTVAR_BW_DEFAULT	4
 
 /* rttvar smooth avg for bw calc  */
-#define SCTPCTL_RTTVAR_RTT_DESC	"Shift amount for rtt smothing on rtt calc"
+#define SCTPCTL_RTTVAR_RTT_DESC	"Shift amount for rtt smoothing on rtt calc"
 #define SCTPCTL_RTTVAR_RTT_MIN	0
 #define SCTPCTL_RTTVAR_RTT_MAX	32
 #define SCTPCTL_RTTVAR_RTT_DEFAULT	5
 
-#define SCTPCTL_RTTVAR_EQRET_DESC	"When rtt and bw are unchanged return what"
+#define SCTPCTL_RTTVAR_EQRET_DESC	"What to return when rtt and bw are unchanged"
 #define SCTPCTL_RTTVAR_EQRET_MIN	0
 #define SCTPCTL_RTTVAR_EQRET_MAX	1
 #define SCTPCTL_RTTVAR_EQRET_DEFAULT	0
 
+#define SCTPCTL_RTTVAR_STEADYS_DESC	"How many the sames it takes to try step down of cwnd"
+#define SCTPCTL_RTTVAR_STEADYS_MIN	0
+#define SCTPCTL_RTTVAR_STEADYS_MAX	0xFFFF
+#define SCTPCTL_RTTVAR_STEADYS_DEFAULT	20	/* 0 means disable feature */
+
+#define SCTPCTL_RTTVAR_DCCCECN_DESC	"Enable for RTCC CC datacenter ECN"
+#define SCTPCTL_RTTVAR_DCCCECN_MIN	0
+#define SCTPCTL_RTTVAR_DCCCECN_MAX	1
+#define SCTPCTL_RTTVAR_DCCCECN_DEFAULT	1	/* 0 means disable feature */
+
 #if defined(SCTP_DEBUG)
 /* debug: Configure debug output */
 #define SCTPCTL_DEBUG_DESC	"Configure debug output"
diff --git a/sys/netinet/sctp_timer.c b/sys/netinet/sctp_timer.c
index 6ff0f581404..bccf7dfc739 100644
--- a/sys/netinet/sctp_timer.c
+++ b/sys/netinet/sctp_timer.c
@@ -820,6 +820,12 @@ start_again:
 			/* reset the TSN for striking and other FR stuff */
 			chk->rec.data.doing_fast_retransmit = 0;
 			/* Clear any time so NO RTT is being done */
+
+			if (chk->do_rtt) {
+				if (chk->whoTo->rto_needed == 0) {
+					chk->whoTo->rto_needed = 1;
+				}
+			}
 			chk->do_rtt = 0;
 			if (alt != net) {
 				sctp_free_remote_addr(chk->whoTo);
diff --git a/sys/netinet/sctputil.c b/sys/netinet/sctputil.c
index a1b345031cb..ffd131ffc6c 100644
--- a/sys/netinet/sctputil.c
+++ b/sys/netinet/sctputil.c
@@ -1370,11 +1370,10 @@ sctp_iterator_worker(void)
 		SCTP_IPI_ITERATOR_WQ_UNLOCK();
 		CURVNET_SET(it->vn);
 		sctp_iterator_work(it);
-
+		sctp_it_ctl.cur_it = NULL;
 		CURVNET_RESTORE();
 		SCTP_IPI_ITERATOR_WQ_LOCK();
 		if (sctp_it_ctl.iterator_flags & SCTP_ITERATOR_MUST_EXIT) {
-			sctp_it_ctl.cur_it = NULL;
 			break;
 		}
 		/* sa_ignore FREED_MEMORY */
@@ -2469,7 +2468,7 @@ sctp_calculate_rto(struct sctp_tcb *stcb,
     struct sctp_association *asoc,
     struct sctp_nets *net,
     struct timeval *told,
-    int safe, int local_lan_determine)
+    int safe, int rtt_from_sack)
 {
 	/*-
 	 * given an association and the starting time of the current RTT
@@ -2507,9 +2506,18 @@ sctp_calculate_rto(struct sctp_tcb *stcb,
 
 	/* computer rtt in ms */
 	rtt = net->rtt / 1000;
-
-	/* Do we need to determine the lan type? */
-	if ((local_lan_determine == SCTP_DETERMINE_LL_OK) &&
+	if ((asoc->cc_functions.sctp_rtt_calculated) && (rtt_from_sack == SCTP_RTT_FROM_DATA)) {
+		/*
+		 * Tell the CC module that a new update has just occurred
+		 * from a sack
+		 */
+		(*asoc->cc_functions.sctp_rtt_calculated) (stcb, net, &now);
+	}
+	/*
+	 * Do we need to determine the lan? We do this only on sacks i.e.
+	 * RTT being determined from data not non-data (HB/INIT->INITACK).
+	 */
+	if ((rtt_from_sack == SCTP_RTT_FROM_DATA) &&
 	    (net->lan_type == SCTP_LAN_UNKNOWN)) {
 		if (net->rtt > SCTP_LOCAL_LAN_RTT) {
 			net->lan_type = SCTP_LAN_INTERNET;