diff --git a/openbsc/contrib/gprs/gprs-buffer-count.lua b/openbsc/contrib/gprs/gprs-buffer-count.lua
new file mode 100644
index 0000000..ca8864a
--- /dev/null
+++ b/openbsc/contrib/gprs/gprs-buffer-count.lua
@@ -0,0 +1,80 @@
+-- I count the buffer space needed for LLC PDUs in the worse case and print it
+
+do
+	local function init_listener()
+		-- handle the port as NS over IP
+		local udp_port_table = DissectorTable.get("udp.port")
+		local gprs_ns_dis = Dissector.get("gprs_ns")
+		udp_port_table:add(23000,gprs_ns_dis)
+
+		-- bssgp filters
+		local bssgp_pdu_get = Field.new("bssgp.pdu_type")
+		local bssgp_delay_get = Field.new("bssgp.delay_val")
+		local llcgprs_get = Field.new("llcgprs")
+		local pdus = nil
+
+		print("START...")
+
+		local tap = Listener.new("ip", "udp.port == 23000 && bssgp.pdu_type == 0")
+		function tap.packet(pinfo,tvb,ip)
+			local pdu = bssgp_pdu_get()
+			local len = llcgprs_get().len
+			local delay = bssgp_delay_get()
+
+			-- only handle bssgp, but we also want the IP frame
+			if not pdu then
+				return
+			end
+
+			if tonumber(tostring(delay)) == 65535 then
+				pdus = { next = pdus,
+					 len = len,
+					 expires = -1 }
+			else
+				local off = tonumber(tostring(delay)) / 100.0
+				pdus = { next = pdus,
+					 len = len,
+					 expires = pinfo.rel_ts + off }
+			end
+			local now_time = tonumber(tostring(pinfo.rel_ts))
+			local now_size = 0
+			local l = pdus
+			local prev = nil
+			local count = 0
+			while l do
+				if now_time < l.expires or l.expires == -1 then
+					now_size = now_size + l.len
+					prev = l
+					l = l.next
+					count = count + 1
+				else
+					-- delete things
+					if prev == nil then
+						pdus = nil
+						l = nil
+					else
+						prev.next = l.next
+						l = l.next
+					end
+				end
+			end
+--			print("TOTAL: " .. now_time .. " PDU_SIZE: " .. now_size)
+			print(now_time .. " " .. now_size / 1024.0 .. " " .. count)
+--			print("NOW: " .. tostring(pinfo.rel_ts) .. " Delay: " .. tostring(delay) .. " Length: " .. tostring(len))
+		end
+
+		function tap.draw()
+			-- well... this will not be called...
+--			for ip,bssgp_histo in pairs(dumpers) do
+--				print("IP " .. ip)
+--			end
+			print("END")
+		end
+
+		function tap.reset()
+			-- well... this will not be called...
+		end
+	end
+
+	init_listener()
+end