Index: sys/netinet/cc/cc_newreno.c
===================================================================
--- sys/netinet/cc/cc_newreno.c
+++ sys/netinet/cc/cc_newreno.c
@@ -48,6 +48,13 @@
  *   http://caia.swin.edu.au/urp/newtcp/
  */
 
+/*
+ * Dec 2014 garmitage@swin.edu.au
+ * Borrowed code fragments from cc_cdg.c to add modifiable beta
+ * via sysctls.
+ *
+ */
+
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
@@ -68,11 +75,23 @@
 #include <netinet/cc/cc.h>
 #include <netinet/cc/cc_module.h>
 
+#define	CAST_PTR_INT(X) (*((int*)(X)))
+
+#ifndef	VIMAGE
+#define	vnet_sysctl_handle_uint(oidp, arg1, arg2, req) \
+    sysctl_handle_int(oidp, arg1, arg2, req)
+#endif
+
 static void	newreno_ack_received(struct cc_var *ccv, uint16_t type);
 static void	newreno_after_idle(struct cc_var *ccv);
 static void	newreno_cong_signal(struct cc_var *ccv, uint32_t type);
 static void	newreno_post_recovery(struct cc_var *ccv);
 
+static VNET_DEFINE(uint32_t, newreno_beta_loss) = 50;
+static VNET_DEFINE(uint32_t, newreno_beta_ecn) = 80;
+#define V_newreno_beta_loss VNET(newreno_beta_loss)
+#define V_newreno_beta_ecn VNET(newreno_beta_ecn)
+
 struct cc_algo newreno_cc_algo = {
 	.name = "newreno",
 	.ack_received = newreno_ack_received,
@@ -195,10 +214,14 @@
 	KASSERT((type & CC_SIGPRIVMASK) == 0,
 	    ("%s: congestion signal type 0x%08x is private\n", __func__, type));
 
-	cwin = max(cwin / 2 / mss, 2) * mss;
 
 	switch (type) {
 	case CC_NDUPACK:
+		if (V_tcp_do_abe)
+			cwin = max((cwin * V_newreno_beta_loss)/100 / mss, 2) * mss;
+		else
+			cwin = max(cwin / 2 / mss, 2) * mss;
+
 		if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
 			if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
 				CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
@@ -208,6 +231,11 @@
 		}
 		break;
 	case CC_ECN:
+		if (V_tcp_do_abe)
+			cwin = max((cwin * V_newreno_beta_ecn)/100 / mss, 2) * mss;
+		else
+			cwin = max(cwin / 2 / mss, 2) * mss;
+
 		if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
 			CCV(ccv, snd_ssthresh) = ssthresh_on_loss;
 			CCV(ccv, snd_cwnd) = cwin;
@@ -252,5 +280,28 @@
 	}
 }
 
+static int
+newreno_beta_handler(SYSCTL_HANDLER_ARGS)
+{
+	if (req->newptr != NULL &&
+		(CAST_PTR_INT(req->newptr) <= 0 || CAST_PTR_INT(req->newptr) > 100))
+		return (EINVAL);
+
+	return (vnet_sysctl_handle_uint(oidp, arg1, arg2, req));
+}
+
+SYSCTL_DECL(_net_inet_tcp_cc_newreno);
+SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, newreno, CTLFLAG_RW, NULL,
+    "New Reno related settings");
+
+SYSCTL_PROC(_net_inet_tcp_cc_newreno, OID_AUTO, beta_loss,
+	CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW,
+	&VNET_NAME(newreno_beta_loss), 3, &newreno_beta_handler, "IU",
+	"newreno beta loss, specified as number between 0 and 100");
+
+SYSCTL_PROC(_net_inet_tcp_cc_newreno, OID_AUTO, beta_ecn,
+	CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW,
+	&VNET_NAME(newreno_beta_ecn), 3, &newreno_beta_handler, "IU",
+	"newreno beta ecn, specified as number between 0 and 100");
 
 DECLARE_CC_MODULE(newreno, &newreno_cc_algo);
Index: sys/netinet/tcp_input.c
===================================================================
--- sys/netinet/tcp_input.c
+++ sys/netinet/tcp_input.c
@@ -181,6 +181,11 @@
     &VNET_NAME(tcp_abc_l_var), 2,
     "Cap the max cwnd increment during slow-start to this number of segments");
 
+VNET_DEFINE(int, tcp_do_abe) = 0;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, abe, CTLFLAG_VNET | CTLFLAG_RW,
+    &VNET_NAME(tcp_do_abe), 0,
+    "Enable ABE for NewReno (Alternative Backoff with ECN)");
+
 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN");
 
 VNET_DEFINE(int, tcp_do_ecn) = 2;
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -708,6 +708,7 @@
 VNET_DECLARE(int, path_mtu_discovery);
 VNET_DECLARE(int, tcp_do_rfc3465);
 VNET_DECLARE(int, tcp_abc_l_var);
+VNET_DECLARE(int, tcp_do_abe);
 #define	V_tcb			VNET(tcb)
 #define	V_tcbinfo		VNET(tcbinfo)
 #define	V_tcp_mssdflt		VNET(tcp_mssdflt)
@@ -720,6 +721,7 @@
 #define	V_path_mtu_discovery	VNET(path_mtu_discovery)
 #define	V_tcp_do_rfc3465	VNET(tcp_do_rfc3465)
 #define	V_tcp_abc_l_var		VNET(tcp_abc_l_var)
+#define	V_tcp_do_abe		VNET(tcp_do_abe)
 
 VNET_DECLARE(int, tcp_do_sack);			/* SACK enabled/disabled */
 VNET_DECLARE(int, tcp_sc_rst_sock_fail);	/* RST on sock alloc failure */