Re: Request for link-layer header type (XRA)

[Guy Harris <guy () alum mit edu>]

On Dec 5, 2017, at 4:47 AM, Bruno Verstuyft <bruno.verstuyft () gmail com> wrote:

> 2017-12-04 22:21 GMT+01:00 Guy Harris <guy () alum mit edu>:
>
> > On Nov 16, 2017, at 1:21 AM, Bruno Verstuyft <bruno.verstuyft () gmail com>
> > wrote:
> >
> > > we put the specification of the XRA header online.
> >
> > The MAC document speaks of "logical" upstream and downstream channels; are
> > those what the "Downstream Channel ID" and "Upstream Channel ID" TLVs refer
> > to?
> Yes, from the MULPI spec:
> Logical (Upstream) Channel: A MAC entity identified by a unique channel ID
> and for which bandwidth is allocated by an
> associated MAP message. A physical upstream channel may support multiple
> logical upstream
> channels. The associated UCD and MAP messages completely describe the
> logical channel.

You might want to say "ID of downstream *logical* channel" in the remarks for "Downstream Channel ID"; the remarks for 
"Upstream Channel ID" already say "logical upstream channel" (is it best to say "logical XXX channel" or "XXX logical 
channel"?).

> > To what do the start and stop minislots in the "Minislot ID" TLV refer?
>
> These are the minislots, relative in an OFDMA frame. The minislot with the
> lowest subcarriers has id 0.

So those are the minislots from section 7.4.1 "Signal Processing Requirements" of the PHY specification?

> > What do the "Symbol ID", "Burst ID", and "Subplot ID" TLVs contain?
>
> Symbol ID is a number assigned to each symbol by our hardware. This is
> mainly used for timing calculations. It can also be used to visualize the
> correlation between NCP (Next Codeword Pointers) and the corresponding
> downstream data packets.

So to which symbol in the packet does that refer?

> Burst ID is used to map mac frames to the corresponding databurst. A
> databurst can e.g. contain a segment:(see MULPI 7.2.4
> Continuous Concatenation and Fragmentation). This means a segment can
> contain multiple Mac frames, or a Mac frame can be spread over multiple
> segments. In our sniffer, we extract these Mac frames from the segments. To
> save the information of which Mac frame belongs to which segment (or
> multiple segments), we use the Burst ID: each data burst gets a unique
> Burst ID. In the Mac Frame the "Burst Info"/"Burst ID reference" is used to
> reference these Burst IDs.

So your sniffer assigns the Burst IDs?

There's a variable-length "Burst ID" field and a "Burst ID Reference" field.  Does the "Burst ID" field contain a 
single burst ID?  If so, to which burst was that ID assigned?  And what does the "Burst ID Reference" field contain?

> > Does the SID TLV contain the Service Identifier for the service flow in
> > which the packet was sent?
>
> Yes

You might want to spell out "Service Identifier" in the remarks.

> > Does the IUC TLV contain the Interval Usage Code for the burst if the
> > packet is a burst?
>
> Yes

You might want to spell out "Interval Usage Code" in the remarks.

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