icmp6_seq
icp6->icmp6_seq = seq;
seq = icp6->icmp6_seq;
icp6->icmp6_seq = htons(i);
TCHECK(dp->icmp6_seq);
ntohs(dp->icmp6_id), ntohs(dp->icmp6_seq));
icp->icmp6_seq = htons(seq);
*seq = ntohs(((struct icmp6_hdr *)up)->icmp6_seq);
*seq = ntohs(icp->icmp6_seq);