diff --git a/src/mpBurstBlocks.py b/src/mpBurstBlocks.py
index 91c9856..98ecc79 100644
--- a/src/mpBurstBlocks.py
+++ b/src/mpBurstBlocks.py
@@ -6,7 +6,7 @@ class BurstBlocksAggregator:
 		# csv_file="c2s_seq_1.csv"
 		# minimum delay to observe to identify the beginning of a block
 		self.min_block_sep = 0.1 
-		self.headers = [ "ts", "map_begin", "subflow", "is_seq", "map-end", "is_reinject" ] 
+		self.headers = [ "ts", "map_begin", "subflow", "is_seq", "map_end", "is_reinject" ] 
 		self.log = open(dest_dir+"/burst_block_aggregator.log","w")
 		self.csv_file=dest_dir+"/"+"c2s_seq_1.csv"
 		self.a = np.genfromtxt (self.csv_file, delimiter=",")
@@ -23,39 +23,74 @@ class BurstBlocksAggregator:
 		b=0
 		# iteration, we can start at packet 1
 		i=1
+		previous=0
 		while i<len(self.a):
-			if self.a[i][self.c("ts")]-self.a[i-1][self.c("ts")]>0.1:
-				print >>self.log, "previous block:", "{:10.8f}".format(self.a[i-1][self.c("ts")]), "seq:", self.a[i-1][self.c("map_begin")]
-				print >>self.log, "found block starting at ", "{:10.8f}".format(self.a[i][self.c("ts")]), "seq:", self.a[i][self.c("map_begin")]
-				print >>self.log, "next block:", "{:10.8f}".format(self.a[i+1][self.c("ts")]), "seq:", self.a[i+1][self.c("map_begin")]
-				print >>self.log,"--------------------------------------"
-				# the ranges we use here are inclusive, ie the range contains both elements.
-				self.blocks.append((b,i-1))
-				b=i
+			if self.a[i][self.c("is_seq")]==1:
+				# in this case we look for the start of a new sending block
+				if b==None:
+					b=i
+					print >>self.log, "previous seq packet:", "{:10.8f}".format(self.a[previous][self.c("ts")]), "seq:", self.a[previous][self.c("map_begin")]
+					print >>self.log, "found block starting at ", "{:10.8f}".format(self.a[i][self.c("ts")]), "seq:", self.a[i][self.c("map_begin")]
+				# we know the start of the block and look for its last packet
+				elif self.a[i][self.c("ts")]-self.a[previous][self.c("ts")]>0.1:
+					print >>self.log, "next block:", "{:10.8f}".format(self.a[i+1][self.c("ts")]), "seq:", self.a[i+1][self.c("map_begin")]
+					print >>self.log,"--------------------------------------"
+					# the ranges we use here are inclusive, ie the range contains both elements.
+					self.blocks.append((b,previous))
+					b=i
+				# keep track of previous seq packet
+				previous=i
 			i=i+1
-		self.blocks.append((b,i-1))
+		self.blocks.append((b,previous))
 		print >>self.log, "# blocks: ", len(self.blocks)
 	def extract_times(self):
 		for i in range(len(self.blocks)):
+			print >>self.log, "Block " + str(i)
+			print >>self.log, "---------------------"
 			first,last = self.blocks[i]
+			print >>self.log, "first packet[" + str(first) +"] at:", "{:10.6f}".format(self.a[first][self.c("ts")]), "seq:", self.a[first][self.c("map_begin")]
+			print >>self.log, "last packet [" + str(last) +"] at :", "{:10.6f}".format(self.a[last][self.c("ts")]), "seq:", self.a[last][self.c("map_begin")]
 			t1 = self.a[first][self.c("ts")]
 			# +1 because our ranges are inclusive
 			packets = self.a[first:last+1]
-			j=0
-			biggest_ack=-1
-			while j<len(packets):
-				if packets[j][self.c("is_seq")]==0:
-					if biggest_ack==-1:
-						biggest_ack=j
-					elif packets[j][self.c("map_begin")]>packets[biggest_ack][self.c("map_begin")]:
-						biggest_ack=j
-				j=j+1
-			self.times.append([first, first+biggest_ack, packets[biggest_ack][self.c("ts")] - packets[0][self.c("ts")], packets[0][self.c("ts")], packets[biggest_ack][self.c("ts")]]) 
+			biggest_seq_index=self.find_biggest_seq_in_block(packets)
+			biggest_seq = packets[biggest_seq_index][self.c("map_end")]
+			print >>self.log, "biggest_seq = " + str(biggest_seq)
+			ack_index, ack_packet=self.find_ack_for_seq(biggest_seq, biggest_seq_index)
+			print >>self.log, "ack time = " + "{:10.6f}".format(self.a[ack_index][self.c("ts")])
+			print >>self.log, "ack index = " + str(ack_index)
+			print >>self.log, "block time = " + "{:10.6f}".format(ack_packet[self.c("ts")] - packets[0][self.c("ts")])
+			self.times.append([first, ack_index, ack_packet[self.c("ts")] - packets[0][self.c("ts")]   , packets[0][self.c("ts")], ack_packet[self.c("ts")]  ]) 
+			print >>self.log, "############################"
+		print >>self.log, "---------------------------------------------"
+		print >>self.log, "block times = " + str(self.times)
 		self.times = np.array(self.times)
 		np.set_printoptions(precision=6)
 		block_times= self.times[:,2]
 		block_times.sort()
 		self.block_times=block_times[1:-2]
+	def find_ack_for_seq(self, seq, start_index):
+		i=start_index
+		while i<len(self.a):
+			# find ack packets
+			if self.a[i][self.c("is_seq")]==0:
+				if self.a[i][self.c("map_begin")]>=seq:
+					return (i,self.a[i])
+			i=i+1
+		return None
+
+	def find_biggest_seq_in_block(self, packets):
+		biggest_seq=-1
+		j=0
+		while j<len(packets):
+			if packets[j][self.c("is_seq")]==1:
+				if biggest_seq==-1:
+					biggest_seq=j
+				elif packets[j][self.c("map_begin")]>packets[biggest_seq][self.c("map_begin")]:
+					biggest_seq=j
+			j=j+1
+		return biggest_seq
+		
 	def __del__(self):
 		self.log.close()