Meaning of preceding

Questions on DDP receiver

Assume a DDP receiver has a set of buffers "associated with" MSN
0,1,2,3,4 and 5. (unexpected association for MSN 0) for a given constant
QN.

Question 1:

If the first DDP segment that arrives has MSN = 0 (no TCP sequence gap,
violation of initial MSN rule) does the receiver: (1) Place and deliver,
(2) place and hold, (3) signal error to ULP.

Question 2:

If MSN 1 has been received, and the next MSN is 3 (with no TCP sequence
gap, sender protocol error) what is the receiver's expected behavior?


The issue here is that the tests of section 9.1 appear to allow
placement for the above two situations. Further the delivery conditions
of section 7.4 use the word "preceding", which up to this point I have
assumed to be understood in TCP sequence number space. If those are the
only two conditions then it seems like DDP should "deliver" for both
questions 1 and questions 2. However if "preceding", for untagged
buffers, is based on MSN number then delivery would not be valid.

So, the bottom line question is - does the receiver have to track the
first missing MSN to determine message delivery?



Barry Reinhold
Lamprey Networks
[email protected]
(603) 868-8411