Could TCP allow IP to checksum the data?
TCP cannot permit IP to checksum data yet IP has its own checksum for its header. IP layer is fundamentally responsible for routing of IP datagram's immaterial of whether which packet is proposed for TCP services or UDP services. Therefore immaterial of what information is enclosed in data part, IP layer is only liable for routing of packets and all the matters related to error control, flow control and error detect ion regarding Routing only. Therefore IP does not contain a checksum for data unlike TCP.