Re: draft-ietf-v6ops-mech-v2-00.txt

["Fred L. Templin" <ftemplin@IPRG.nokia.com>]

Erik Nordmark wrote:

> >    Total Length:
> >       Payload length from IPv6 header plus length of IPv6 and
> >       IPv4 headers plus length of optional padding (i.e., IPv6
> >       payload length plus a minimum of 60 bytes)
> >    
> I don't understand the motivation for your suggestion.
>
> The document doesn't talk about any optional padding.
> Are you proposing that we add the ability to optionally pad
> the packets as part of encapsulating them?
Yes.

> What problem would allowing optional padding solve?
Two possible applications for the optional padding are:

 1) traffic confidentiality
 2) path MTU probing using arbitrary data packets

Moreover, I see no requirement that a decapsulator check that
IPv4_len = IPv6_len + 60. To be sure, the only requirement
for correct operation is that IPv4_len >= IPv6_len +60.

Fred
ftemplin@iprg.nokia.com