On Feb 3, 2011, at 8:47 AM, M.Baris Demiray wrote:
> Hello again,
>
> I have solved almost all the problems that I mentioned below and now I
> am sure that I should ask for a new DLT value for STANAG 5066 [1] MAC
> (Medium Access Control Sublayer) PDUs. Currently I am able to dissect
> these PDUs using DLT number 147 (USER0) using Wireshark 1.4.3 and I'd
> like to have this dissector and corresponding DLT value in the main
> stream.
>
> I might add that STANAG 5066 SIS layer is already defined in Wireshark
> [2] yet it can only dissect the packets transferred between STANAG
> 5066 and its clients.
OK, that answers the questions I asked in my previous message.
> Now, what I propose is to have the same
> functionality for the interface between STANAG 5066 and HF modem as
> well. What else should I provide regarding this protocol to ask for a
> DLT value?
So that protocol is presumably the one mentioned in the isode.com white paper:
At the modem level, STANAG 5066 uses packets (DPDUs) of a size
appropriate to the modem speed. At 1200 bits/second 128 bytes will be used,
which is much less than the typical Unit Data. Benefits of using smaller DPDUs
include:
• Acknowledgement is done for each DPDU, so if data loss occurs
when transmitting a DPDU, only that DPDU (and not the whole Unit Data) need to
be retransmitted.
• When higher precedence Unit Data arrives is sent for
transmission by a STANAG 5066 server, sending can begin after transmission of
the current DPDU (i.e., there is no need to wait for the full Unit Data
transmission).
Acknowledgements, often referred to as ARQ (Acknowledgement ReQuest), are used
for Reliable Unit Data and are made for each DPDU. In order to minimize the
number of turnarounds, sending of acknowledgements is delayed. A typical
sequence with two radios might be:
• Radio 1 transmits to Radio 2 for 127 seconds; it sends a
number of DPDUs.
• Radio 2 transmits to Radio 1 for 127 seconds; it sends
acknowledgments for the DPDUs received from Radio 1; then it sends some DPDUs.
• Radio 1 transmits to Radio 2 for 127 seconds; it sends
acknowledgements for the DPDUs received from Radio 2; then it works out which
DPDUs failed to transmit last time and resends them; then it sends more DPDUs.
with the packets for the MAC layer being the DPDUs. Is that correct?
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