[radvd-devel-l] how is the length field calcuted for the radvd options

Pekka Savola pekkas at netcore.fi
Tue Feb 28 10:33:45 EST 2006

On Tue, 28 Feb 2006, Magesh mannar wrote:
>  I am going through the radvd src code. In send.c program, i find the send_ra() fn which creates the various options and sends the ra using sendmsg.
>  I suppose the msgs are created in the TLV format. I am wondering 
> how the length filed is calculated. For example, while creating the 
> prefix info option, the length field is set to 4 
> (pinfo->nd_opt_pi_len = 4;). Can you please let me know how the 
> length field is calculated and how it is 4 for the prefix option
>  Sorry for troubling with a trivial doubt.

Take a look at RFC2461, in particular section 4.6.2.

I hope reading the specifications will help you with similar doubts in 
the future.

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

More information about the radvd-devel-l mailing list