+ # IPs used in packet headers.
+ p1_src_start_ip = u"192.168.0.0"
+ p1_src_end_ip = u"192.168.255.255"
+ p1_dst_start_ip = u"20.0.0.0"
+ p1_dst_end_ip = u"20.0.255.255"
+
+ # Headers length, not sure why TRex needs 32B for segment header.
+ real_headers_size = 70 # 18B L2 + 20B IPv4 + 32B TCP.
+ trex_headers_size = real_headers_size - 12 # As if TCP header is 20B.
+ trex_mss = self.framesize - trex_headers_size
+ real_mss = trex_mss - 12 # TRex honors segment header+data limit.
+ data_size = self.n_data_frames * real_mss
+