RE: [EFM] Should There Be A Sequence Number In Variable Request/Resp onse PDUs?
(limited becuase I haven't read this particular protocol) opinion is that in
general information providing protocols should be designed to be
'connectionless' wherever possible for simplicity, that is to say that
information that is sent completely describes itself.
such a design it is not neccessary to send sequence/correlation numbers in the
protocol even if there are multiple outstanding requests, and they should be
avoided. It is up to the requestor of the information to match the self
describing information received with any outstanding user requests for such
information - of which there may be one, none (user may have given up/gone
away), or several (several users may want the same information). It is also up
to the requestor to moderate the nuber of times prompts or solicitations are
sent for information.
least the responses contain the information on which values are being returned,
so to some extent one can simply use that as a kind of
However, I agree that a correlator field might well be useful to
correlate requests and responses, but I'd recommend calling it a correlator
rather than a sequence number, and avoid any language requiring it to be
incremented in each request etc. Simply say that the correlator from the
variable request PDU should be returned in each resulting variable response
PDU - then, anyone who wanted to, could set it to a unique value, and
anyone else could just set it to zero and ignore it when
anyone else have an opinion?
Variable Request and
Response PDUs don't have a sequence number field.
If one is allowed to send multiple outstanding Variable
Requests, then how is to
match a response to its corresponding request? Should not we introduce a sequence
number? Sure, to some extent one could match
them by looking at what variables are included, but it's not a sure
If the intention is not
to allow more than one Variable Request at a time, which I think is reasonable
in order to keep the OAM operation simple, then a note to that effect in the
standard would be nice.
Your comments are welcome