Hi,
 I hope you are doing great.
 I am posting this here as I believe Network Programming EXPERTS
visiting this group will help me out.

  Problem: I am trying to send IPV6 HopByHop extension header with
ROUTER ALERT and receive at the other end. For router alert TLV (T=5,
L=2, V=0x0001: RFC 2711). Now I am filling the structure as follows..

   struct msghdr{
      .....
      .....
    msg_control ------|
    msg_controllen=20 |
      .....           |
   }                  |
                      ->  --------------------------------
                         |    cmsg_len = 18                |
                          --------------------------------
                         |  cmsg_level=IPPROTO_IPV6        |
                          --------------------------------
                         |  cmsg_type = IPV6_HOPOPTS       |
                          ---------------------------------
                         |Next Hdr|Next Hdr Len|Type|Length|
                         | 0x00   |     0x00   |0x05|0x02  |
                          ---------------------------------
                         |2-byte value |<--2 bytes pad---->|
                         | 0x00   0x01 |                   |
                          ---------------------------------

           sendmsg(sockFd->fd, &msg, 0);

           The above calling is used to send the HBH extension header.

       I am using Solaris 2.8. Why it is not received at the other
end? Am I filling the structure correctly? Is my padding OK? I also
tried with 6 bytes padding after value.That also didn't work. BUT WHEN
I SEND HOPLIMIT OPTION, I CAN RECEIVE AT THE OTHER END SUCCESSFULLY.
What is going wrong here?

   Thanks in Advance.

  Sagar