diff --git a/tools/multiple-bgpd.sh b/tools/multiple-bgpd.sh
index f6edae9..c5668e1 100644
--- a/tools/multiple-bgpd.sh
+++ b/tools/multiple-bgpd.sh
@@ -2,100 +2,457 @@
 
 # Public domain, not copyrighted..
 
-NUM=8
+set -u
+
+# number of bgpd instances, not more than 255 at this point.  At least 3 are
+# needed to connect in a ring.
+NUM=7
+
+# The NUM peers can be connected in a ring topology.
+#
+# This sets the proportion of other peers that each peer should be
+# configured to connect to E.g., 20 means each BGP instance will peer with
+# 20% of the other peers before and after it in the ring.  So 10% of the
+# peers prior to this instance in the ring, and 10% of the following peers. 
+# 100 should lead to a full-mesh, for an odd total number of peers.
+#
+# A value of 1 will result in each instance having at least 2 peers in the ring.
+#
+# A value of 0 will disable creating a ring, in which case the only peers 
+# configured will be those in the EXPEERS list.
+PEERPROP=100
+
+# number of routes each BGP instance should advertise
+ADV=10
+# First octet to use for the IPv4 advertisements.  The advertisements
+# will be /32s under this /8.  E.g.  ADVPREF=10 will mean
+# 10.x.y.z/32's are advertised.
+ADVPREF=10
+
+# Base VTY port to allocate Quagga telnet vtys from. VTYBASE+ID will be
+# the port.
 VTYBASE=2610
-ASBASE=64560
-BGPD=/path/to/bgpd
+# Base ASN to allocate ASNs to instances.
+ASBASE=64500
 PREFIX=192.168.145.
 #PREFIX=3ffe:123:456::
 ADDRPLEN=32
 CONFBASE=/tmp
 PIDBASE=/var/run/quagga
-CHOWNSTR=quagga:quagga
+USER=quagga
+GROUP=quagga
 
-for H in `seq 1 ${NUM}` ; do
-	CONF="${CONFBASE}"/bgpd${H}.conf
-	ADDR=${PREFIX}${H}
+# MRAI to specify, where an implementation supports it.
+MRAI=1
+# Connect retry timer
+CONNECTRETRY=1
+
+# The binary locations for BGP instances. 
+declare -A BGP_BINS=(
+	[quagga]=/usr/sbin/bgpd
+	[bird]=/usr/sbin/bird
+	[birdgit]=/home/paul/code/bird/bird
+	[quaggagit]=/home/paul/code/quagga/bgpd/bgpd
+	[exabgp]=/home/paul/code/exabgp/sbin/exabgp
+)
+
+# Configuration generation functions for the BGP instances.
+declare -A BGP_CONFIGGEN=(
+	[quagga]=quagga_config
+	[quaggagit]=quagga_config
+	[bird]=bird_config
+	[birdgit]=bird_config
+	[exabgp]=exabgp_config
+)
+
+# Launch functions for the BGP instances.
+declare -A BGP_LAUNCH=(
+	[quagga]=quagga_launch
+	[quaggagit]=quagga_launch
+	[bird]=bird_launch
+	[birdgit]=bird_launch
+	[quaggagit]=quagga_launch
+	[exabgp]=exabgp_launch
+)
+
+# the instances to run, in the order they should appear in the ring
+# (repeated over until there are $NUM instances).  The value must exist as a
+# key into the above two arrays.
+declare -a BGP_INSTANCES=(
+	quagga
+	bird
+	quaggagit
+	exabgp
+)
+
+# Peers to configure, that are external to this script. One list of IPs, with
+# corresponding list of their ASes.
+#
+# e.g.:
+#EXPEERS=(192.168.147.{1..10})
+#EXPEERASES=($(seq $((ASBASE+11)) $(($ASBASE+20))))
+
+EXPEERS=()
+EXPEERASES=()
+
+############################################################################
+# Can override any of the above from a supplied file with declarations
+CONFWRITE=Y
+if [ $# -gt 0 ] ; then
+	echo "multiple-bgpd.sh: sourcing config from $1"
+	[ -f "$1" ] && . "$1"
 	
-	if [ ! -e "$CONF" ] ; then
-		# This sets up a ring of bgpd peerings
-		NEXT=$(( ($H % ${NUM}) + 1 ))
-		PREV=$(( (($H + $NUM - 2) % ${NUM}) + 1 ))
-		NEXT2=$(( (($H+1) % ${NUM}) + 1 ))
-		PREV2=$(( (($H + $NUM - 3) % ${NUM}) + 1 ))
-		NEXTADDR="${PREFIX}${NEXT}"
-		NEXTAS=$((${ASBASE} + $NEXT))
-		PREVADDR="${PREFIX}${PREV}"
-		PREVAS=$((${ASBASE} + $PREV))
-		NEXT2ADDR="${PREFIX}${NEXT2}"
-		NEXT2AS=$((${ASBASE} + $NEXT2))
-		PREV2ADDR="${PREFIX}${PREV2}"
-		PREV2AS=$((${ASBASE} + $PREV2))
-		ASN=$((64560+${H}))
+	# keep config, if exists
+	[ $# -gt 1 ] && [ "$2" = "k" ] && CONFWRITE=N	
+fi
+
+############################################################################
+# Internal variables.
+
+# Number of peers for each instance to peer with
+PEERNUM=$(( ($NUM-1) * $PEERPROP / 100  ))
+[ "$PEERNUM" -gt $(($NUM-1)) ] && PEERNUM=$(($NUM-1))
+
+# the 'range', i.e.  how many of the previous and next peers in the ring to
+# connect to
+PEERRANGE=$(( $PEERNUM/2 ))
+[ "$PEERPROP" -gt 0 -a "$NUM" -ge 3 -a  "$PEERRANGE" -le 0 ] && PEERRANGE=1
+
+# and a convenience expansion
+PEEREXP=""
+if [ "$PEERRANGE" -gt 0 ]; then
+	PEEREXP=($(seq -${PEERRANGE} ${PEERRANGE}))
+	# dont need 0
+	unset PEEREXP[PEERRANGE]
+fi
+
+#echo ${PEEREXP[@]}
+
+############################################################################
+## helpers
+
+# translate instance ID to its address.
+id2addr () {
+	local ID=$1
+	echo ${PREFIX}${ID}
+}
+
+# return the ID of a peer, in terms of an offset on the given instance's ID.
+#
+# E.g., given an ID of 1 and an offset of -1, if there are 10 instances overall,
+# this will return 10.
+peeridoff () {
+	local ID=$1
+	local OFF=$2
+	echo $(( (($ID + $OFF - 1  + $NUM) % $NUM) + 1  ))
+}
+
+# return IPv4 address to advertise, for given instance ID and number.
+advipaddr () {
+	local ID=$1
+	local N=$2
+	echo "$ADVPREF.$(( ($N >> 16) %256 )).$(( ($N >> 8) % 256 )).$(( $N % 256  ))"
+}
+
+############################################################################
+# launch functions
+#
+# do not daemonise, so that all launched instances can be killed by killing
+# the script.
+#
+
+quagga_launch () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+	local BIN=$4
+	local CONF=$5
+	${BIN} -i "${PIDBASE}"/bgpd${ID}.pid \
+		   -l ${ADDR} \
+		   -f "${CONF}" \
+		   -u $USER -g $GROUP \
+		   -P $((${VTYBASE}+${ID}))
+}
+
+exabgp_launch () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+	local BIN=$4
+	local CONF=$5
+	
+	env exabgp.api.file="${PIDBASE}"/exabgp${ID}.ctl \
+	exabgp.daemon.pid="${PIDBASE}"/bgpd${ID}.pid \
+	exabgp.daemon.daemonize=false \
+	exabgp.tcp.bind=${ADDR} \
+	exabgp.log.enable=false \
+	exabgp.daemon.user=quagga \
+	${BIN} ${CONF}
+}
+
+bird_launch () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+	local BIN=$4
+	local CONF=$5
+	${BIN} -P "${PIDBASE}"/bird${ID}.pid \
+		   -c "${CONF}" \
+		   -s "${PIDBASE}"/bird${ID}.ctl \
+		   -f
+}
+
+#######################################################################
+#
+# functions to write the configuration for instances
+#
+
+exabgp_config () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+	
+	local N
+	local P
+	
+	cat <<- EOF
+		group default {
+		  local-address $ADDR;
+		  local-as $ASN;
+		  router-id $ADDR;
+		  
+		  capability {
+		    asn4 enable;
+		  }
+	EOF
+	
+	for N in $(seq 1 $ADV) ; do
+		echo "  static {"
+		echo "    route `advipaddr $ID $N`/32 {"
+		echo "      next-hop $ADDR;"
+		echo "    }"
+		echo "  }" 
+	done
+
+	for P in ${PEEREXP[@]};  do
+		[ "$P" -eq 0 ] && continue;
 		
-		# Edit config to suit.
-		cat > "$CONF" <<- EOF
-			password whatever
-			service advanced-vty
-			!
-			router bgp ${ASN}
-			 bgp router-id ${ADDR}
-			 maximum-paths 32
-			 bgp bestpath as-path multipath-relax
-			 network 10.${H}.1.0/24 pathlimit 1
-			 network 10.${H}.2.0/24 pathlimit 2
-			 network 10.${H}.3.0/24 pathlimit 3
-			 network 10.${H}.0.0/24
-			 neighbor default peer-group
-			 neighbor default update-source ${ADDR}
-			 neighbor default capability orf prefix-list both
-			 neighbor default soft-reconfiguration inbound
-			 neighbor default route-map test out
-			 neighbor ${NEXTADDR} remote-as ${NEXTAS}
-			 neighbor ${NEXTADDR} peer-group default
-			 neighbor ${PREVADDR} remote-as ${PREVAS}
-			 neighbor ${PREVADDR} peer-group default
-			 neighbor ${NEXT2ADDR} remote-as ${NEXT2AS}
-			 neighbor ${NEXT2ADDR} peer-group default
-			 neighbor ${PREV2ADDR} remote-as ${PREV2AS}
-			 neighbor ${PREV2ADDR} peer-group default
-			!
-			 address-family ipv6
-			 network 3ffe:${H}::/48
-			 network 3ffe:${H}:1::/48 pathlimit 1
-			 network 3ffe:${H}:2::/48 pathlimit 3
-			 network 3ffe:${H}:3::/48 pathlimit 3
-			 neighbor default activate
-			 neighbor default capability orf prefix-list both
-			 neighbor default default-originate
-			 neighbor default route-map test out
-			 neighbor ${NEXTADDR} peer-group default
-			 neighbor ${PREVADDR} peer-group default
-			 neighbor ${NEXT2ADDR} peer-group default
-			 neighbor ${PREV2ADDR} peer-group default
-			 exit-address-family
-			!
-			! bgpd still has problems with extcommunity rt/soo
-			route-map test permit 10
-			 set extcommunity rt ${ASN}:1
-			 set extcommunity soo ${ASN}:2
-			 set community ${ASN}:1
-			!
-			line vty
-			 exec-timeout 0 0
-			!
-			end
-		EOF
-		chown ${CHOWNSTR} "$CONF"
+		#local PID=$(( (($ID + $P - 1  + $NUM) % $NUM) + 1  ))
+		local PID=`peeridoff $ID $P`
+		#local PADDR="${PREFIX}${PID}"
+		local PADDR=`id2addr $PID`
+		local PAS=$((${ASBASE} + $PID))
+		
+		echo "  neighbor $PADDR {"
+		#echo "    local-address $ADDR;"
+		#echo "    local-as $ASN;"
+		#echo "    graceful-restart;"
+		#echo "    router-id $ADDR;"
+		echo "    peer-as $PAS;"
+		echo "  }"
+	done
+	
+	for P in ${!EXPEERS[@]};  do
+		echo "  neighbor ${EXPEERS[$P]} {"
+		echo "    peer-as ${EXPEERASES[$P]};"
+		echo "  }"
+	done
+	
+	cat <<- EOF
+		}
+	EOF
+}
+
+quagga_config () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+	
+	local N
+	local P
+	
+	# Edit config to suit.
+	cat <<- EOF
+		password foo
+		service advanced-vty
+		!
+		router bgp ${ASN}
+		 bgp router-id ${ADDR}
+		 !maximum-paths 32
+		 !bgp bestpath as-path multipath-relax
+	EOF
+
+	for N in $(seq 1 $ADV) ; do
+		echo " network `advipaddr $ID $N`/32"
+	done
+
+	cat <<- EOF
+		 neighbor default peer-group
+		 neighbor default update-source ${ADDR}
+		 neighbor default capability orf prefix-list both
+		 !neighbor default soft-reconfiguration inbound
+		 neighbor default advertisement-interval $MRAI
+		 neighbor default timers connect $CONNECTRETRY
+		 neighbor default route-map test out
+	EOF
+
+	for P in ${PEEREXP[@]};  do
+		[ "$P" -eq 0 ] && continue;
+		
+		local PID=`peeridoff $ID $P`
+		local PADDR=`id2addr $PID`
+		local PAS=$((${ASBASE} + $PID))
+		echo " neighbor ${PADDR} remote-as ${PAS}"
+		echo " neighbor ${PADDR} peer-group default"
+	done
+
+	for P in ${!EXPEERS[@]};  do
+		echo " neighbor ${EXPEERS[$P]} remote-as ${EXPEERASES[$P]}"
+		echo " neighbor ${EXPEERS[$P]} peer-group default"
+	done
+
+	cat <<- EOF
+		!
+		 address-family ipv6
+		 network 3ffe:${ID}::/48
+		 network 3ffe:${ID}:1::/48 pathlimit 1
+		 network 3ffe:${ID}:2::/48 pathlimit 3
+		 network 3ffe:${ID}:3::/48 pathlimit 3
+		 neighbor default activate
+		 neighbor default capability orf prefix-list both
+		 neighbor default default-originate
+		 neighbor default route-map test out
+	EOF
+
+	for P in ${PEEREXP[@]};  do
+		[ "$P" -eq 0 ] && continue;
+		
+		local PID=`peeridoff $ID $P`
+		local PADDR=`id2addr $PID`
+		local PAS=$((${ASBASE} + $PID))
+		echo " neighbor ${PADDR} peer-group default"
+	done
+
+	cat <<- EOF
+		 exit-address-family
+		!
+		! bgpd still has problems with extcommunity rt/soo
+		route-map test permit 10
+		 set extcommunity rt ${ASN}:1
+		 set extcommunity soo ${ASN}:2
+		 set community ${ASN}:1
+		!
+		line vty
+		 exec-timeout 0 0
+		!
+		end
+	EOF
+}
+
+bird_config () {
+	local ID=$1
+	local ASN=$2
+	local ADDR=$3
+
+	cat <<- EOF
+		#log "/var/log/bird.log" all;
+		#debug protocols all;
+
+		# Override router ID
+		router id ${ADDR};
+		listen bgp address ${ADDR};
+		
+		protocol kernel { device routes; import all; }
+		protocol device { import all; }
+		
+		function avoid_martians()
+		prefix set martians;
+		{
+		  martians = [ 
+		  	       224.0.0.0/4+, 240.0.0.0/4+
+		  	     ];
+
+		  # Avoid RFC1918 and similar networks
+		  if net ~ martians then return false;
+		  return true;
+		}
+		
+		filter import_filter
+		{
+		  if ! (avoid_martians()) then reject;
+		  accept;
+		}
+		
+		filter set_comm
+		{
+		  bgp_community.add ((${ASN}, 1));
+		  accept;
+		}
+		
+		template bgp peer_conf {
+		  local as ${ASN};
+		  source address ${ADDR};
+		  import filter import_filter;
+		  export filter set_comm;
+		  multihop;
+		}
+	EOF
+	
+	local P;
+	
+	for P in ${PEEREXP[@]};  do
+		[ "$P" -eq 0 ] && continue;
+		
+		local PID=`peeridoff $ID $P`
+		local PADDR=`id2addr $PID`
+		local PAS=$((${ASBASE} + $PID))
+		echo "protocol bgp from peer_conf {"
+		echo " neighbor ${PADDR} as  ${PAS};"
+		echo "}"
+	done
+	
+	for P in ${!EXPEERS[@]};  do
+		echo "protocol bgp from peer_conf {"
+		echo " neighbor ${EXPEERS[$P]} as ${EXPEERASES[$P]};"
+		echo "}"
+	done
+	
+	
+	for N in $(seq 1 $ADV) ; do
+		echo " network `advipaddr $ID $N`/32"
+	done
+}
+
+#######################################################################
+
+for ID in $(seq 1 $NUM); do
+	BGP_INST=${BGP_INSTANCES[${ID} % ${#BGP_INSTANCES[@]}]}
+	BGPBIN=${BGP_BINS[$BGP_INST]}
+	CONF="${CONFBASE}"/${BGP_INST}_bgpd${ID}.conf
+	ASN=$(($ASBASE + ${ID}))
+	ADDR=`id2addr $ID`
+	
+	#if [ ! -e "$CONF" ] ; then
+	if [ ! -e "$CONF" -o "$CONFWRITE" = "Y" ] ; then 
+		${BGP_CONFIGGEN[$BGP_INST]} $ID $ASN $ADDR > "$CONF"
+		chown $USER:$GROUP "$CONF"
 	fi
 	# You may want to automatically add configure a local address
 	# on a loop interface.
 	#
 	# Solaris: ifconfig vni${H} plumb ${ADDR}/${ADDRPLEN} up
-	# Linux:   ip address add ${ADDR}/${ADDRPLEN} dev lo 2> /dev/null
-	${BGPD} -i "${PIDBASE}"/bgpd${H}.pid \
-		-l ${ADDR} \
-		-f "${CONF}" \
-		-P $((${VTYBASE}+${H})) \
-		-d
+	# Linux:
+	#ip address add ${ADDR}/${ADDRPLEN} dev lo 2> /dev/null
+	
+	ip link add dummy${ID} type dummy 2> /dev/null
+	ip link set dev dummy${ID} up
+	ip address add ${ADDR}/${ADDRPLEN} dev dummy${ID} 2> /dev/null
+	
+	${BGP_LAUNCH[$BGP_INST]} $ID $ASN $ADDR $BGPBIN $CONF &
+	
+	sleep 0.1
 done
+
+echo "multiple-bgpd.sh: waiting..."
+
+wait