update_ipv4_header(segs[i], inner_ipv4_offset, inner_id);
update_tcp_header(segs[i], tcp_offset, sent_seq, i < tail_idx);
outer_id++;
update_ipv4_header(segs[i], inner_ipv4_offset, inner_id);
update_tcp_header(segs[i], tcp_offset, sent_seq, i < tail_idx);
outer_id++;