At 01:50 PM 6/20/2006, Ong, Lyndon wrote:
One concern, though, is whether there were strong reasons for originally requiring that the field be set to zero.
Lyndon,There is a long standing protocol design approach to set unused fields to zero. This is done precisely to enable future use of the field. IMO (and if my memory holds) this was so well accepted by the 3209 authors it didn't occur to us to enumerate all the implications of "MUST be zero". I think we did a bit better in rfc3473, but the change was only in response to the brain damage that was seen in 3209 interpretations...
Lou