Re: comments on draft-ietf-shim6-failure-detection-06.txt {3}

[Jari Arkko <jari.arkko@piuha.net>]

Sébastien,
> I have noticed a problem with the Hdr Ext Len field of REAP packets :
> The draft specifies this field like follows :
> -------------
> Next Header, Hdr Ext Len, 0, 0, Checksum
>
>      These are as specified in Section 5.3 of the SHIM6 protocol
>      description [I-D.ietf-shim6-proto].
> --------------
> So, looking at section 5.3 in the shim6 proto draft :
> --------------
> Hdr Ext Len:   8-bit unsigned integer.  Length of the shim6 header in
>                  8-octet units, not including the first 8 octets.
> --------------
> This means any shim6 or reap packet must have a length multiple of 8
> bytes. AFAIK, this is the case  for all shim6 messages defined in the
> proto draft. But that's not true for the failure detection draft in
> the case of the keepalive message : the keepalive message as defined
> is 12 bytes long, which cannot be encoded in the Hdr Ext Len field. I
> suggest extending it with a 4 bytes padding. In the current version of
> the draft I don't see other occurences of this problem.
>
> Nevertheless, when designing options in the future, we should take
> care of also enforcing a length multiple of 8 bytes.
Ah -- good catch. Thanks.

I have added a 32-bit reserved field at the end of the
keepalive message, before the options.

--Jari