diff --git a/include/proto/backend.h b/include/proto/backend.h
index 8fa8c83..444e53a 100644
--- a/include/proto/backend.h
+++ b/include/proto/backend.h
@@ -39,10 +39,10 @@
 int backend_parse_balance(const char **args, char *err,
 			  int errlen, struct proxy *curproxy);
 
-void recount_servers(struct proxy *px);
 void recalc_server_map(struct proxy *px);
 int be_downtime(struct proxy *px);
 void init_server_map(struct proxy *p);
+void fwrr_init_server_groups(struct proxy *p);
 
 /*
  * This function tries to find a running server with free connection slots for
@@ -118,7 +118,9 @@
 		recalc_server_map(px);
 
 	l = h = 0;
-	if (px->srv_act > 1 || (px->srv_act == 0 && px->srv_bck > 1)) {
+
+	/* note: we won't hash if there's only one server left */
+	if (px->lbprm.tot_used > 1) {
 		while ((l + sizeof (int)) <= len) {
 			h ^= ntohl(*(unsigned int *)(&addr[l]));
 			l += sizeof (int);
diff --git a/include/types/backend.h b/include/types/backend.h
index c0c0809..a71db69 100644
--- a/include/types/backend.h
+++ b/include/types/backend.h
@@ -71,6 +71,10 @@
 
 #define PR_O_CONTSTATS	0x80000000	/* continous counters */
 
+
+/* various constants */
+#define BE_WEIGHT_SCALE 256             /* scale between user weight and effective weight */
+
 #endif /* _TYPES_BACKEND_H */
 
 /*
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 53de513..6d27a9b 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -29,6 +29,7 @@
 
 #include <common/appsession.h>
 #include <common/config.h>
+#include <common/ebtree.h>
 #include <common/mini-clist.h>
 #include <common/regex.h>
 #include <common/sessionhash.h>
@@ -64,6 +65,17 @@
 #define PR_CAP_RS      0x0004
 #define PR_CAP_LISTEN  (PR_CAP_FE|PR_CAP_BE|PR_CAP_RS)
 
+/* This structure is used to apply fast weighted round robin on a server group */
+struct fwrr_group {
+	struct eb_root curr;    /* tree for servers in "current" time range */
+	struct eb_root t0, t1;  /* "init" and "next" servers */
+	struct eb_root *init;   /* servers waiting to be placed */
+	struct eb_root *next;   /* servers to be placed at next run */
+	int curr_pos;           /* current position in the tree */
+	int curr_weight;        /* total weight of the current time range */
+	int next_weight;        /* total weight of the next time range */
+}; 
+
 struct proxy {
 	struct listener *listen;		/* the listen addresses and sockets */
 	struct in_addr mon_net, mon_mask;	/* don't forward connections from this net (network order) FIXME: should support IPv6 */
@@ -79,7 +91,7 @@
 	struct list block_cond;                 /* early blocking conditions (chained) */
 	struct list switching_rules;            /* content switching rules (chained) */
 	struct server *srv;			/* known servers */
-	int srv_act, srv_bck;			/* # of running servers */
+	int srv_act, srv_bck;			/* # of servers eligible for LB (UP|!checked) AND (enabled+weight!=0) */
 
 	struct {
 		int tot_wact, tot_wbck;		/* total effective weights of active and backup servers */
@@ -87,11 +99,19 @@
 		int tot_used;			/* total number of servers used for LB */
 		int wmult;			/* ratio between user weight and effective weight */
 		int wdiv;			/* ratio between effective weight and user weight */
+		struct server *fbck;		/* first backup server when !PR_O_USE_ALL_BK, or NULL */
 		struct {
 			struct server **srv;	/* the server map used to apply weights */
 			int rr_idx;		/* next server to be elected in round robin mode */
 			int state;		/* PR_MAP_RECALC */
 		} map;				/* LB parameters for map-based algorithms */
+		struct {
+			struct fwrr_group act;	/* weighted round robin on the active servers */
+			struct fwrr_group bck;	/* weighted round robin on the backup servers */
+		} fwrr;
+		void (*update_server_eweight)(struct server *);/* if non-NULL, to be called after eweight change */
+		void (*set_server_status_up)(struct server *);/* to be called after status changes to UP */
+		void (*set_server_status_down)(struct server *);/* to be called after status changes to DOWN */
 	} lbprm;				/* LB parameters for all algorithms */
 
 	char *cookie_name;			/* name of the cookie to look for */
diff --git a/include/types/server.h b/include/types/server.h
index 3553fc0..4258502 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -2,7 +2,7 @@
   include/types/server.h
   This file defines everything related to servers.
 
-  Copyright (C) 2000-2006 Willy Tarreau - w@1wt.eu
+  Copyright (C) 2000-2007 Willy Tarreau - w@1wt.eu
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -26,6 +26,7 @@
 #include <arpa/inet.h>
 
 #include <common/config.h>
+#include <common/eb32tree.h>
 #include <common/mini-clist.h>
 
 #include <types/buffers.h>
@@ -57,6 +58,7 @@
 struct server {
 	struct server *next;
 	int state;				/* server state (SRV_*) */
+	int prev_state;				/* server state before last change (SRV_*) */
 	int  cklen;				/* the len of the cookie, to speed up checks */
 	char *cookie;				/* the id set in the cookie */
 
@@ -85,6 +87,12 @@
 	char *id;				/* just for identification */
 	unsigned uweight, eweight;		/* user-specified weight, and effective weight */
 	unsigned wscore;			/* weight score, used during srv map computation */
+	unsigned prev_eweight;			/* eweight before last change */
+	unsigned rweight;			/* remainer of weight in the current LB tree */
+	unsigned npos, lpos;			/* next and last positions in the LB tree */
+	struct eb32_node lb_node;               /* node used for tree-based load balancing */
+	struct eb_root *lb_tree;                /* we want to know in what tree the server is */
+	struct server *next_full;               /* next server in the temporary full list */
 
 	unsigned failed_checks, down_trans;	/* failed checks and up-down transitions */
 	unsigned down_time;			/* total time the server was down */