tcpdump mailing list archives
Re: Request for link-layer header type (XRA)
From: Bruno Verstuyft <bruno.verstuyft () gmail com>
Date: Tue, 12 Dec 2017 11:17:52 +0100
2017-12-11 22:31 GMT+01:00 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 comwrote:we put the specification of the XRA header online.The MAC document speaks of "logical" upstream and downstream channels;arethose what the "Downstream Channel ID" and "Upstream Channel ID" TLVsreferto?Yes, from the MULPI spec: Logical (Upstream) Channel: A MAC entity identified by a unique channelIDand 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"?).
In the DOCSIS specs, there is no occurence of the term downstream logical channel, since there are only physical downstream channels. In the upstream, a physical upstream channel (channel around a center frequency) can be divided into multiple logical channels. This division is time based. More information can be found in 5.2.1.1.3.1 "Downstream Data Forwarding in a MAC Domain" and 5.2.1.1.3.2 " Upstream Data Forwarding in a MAC Domain" in the DOCSIS MULPI spec. It is best to say logical upstream channel, since this is the term used in the DOCSIS specs.
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 withthelowest subcarriers has id 0.So those are the minislots from section 7.4.1 "Signal Processing Requirements" of the PHY specification?
Yes, updated in the Xra Header spec.
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?
The first symbol of the packet. Updated in the spec.
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.Tosave 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 usedtoreference 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? Added extra explanation in the spec.
Does the SID TLV contain the Service Identifier for the service flow in which the packet was sent?YesYou might want to spell out "Service Identifier" in the remarks.
Updated in spec.
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.
Updated in spec _______________________________________________ tcpdump-workers mailing list tcpdump-workers () lists tcpdump org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
Current thread:
- Re: Request for link-layer header type (XRA), (continued)
- Re: Request for link-layer header type (XRA) Guy Harris (Nov 22)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 01)
- Re: Request for link-layer header type (XRA) Guy Harris (Dec 01)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 01)
- Re: Request for link-layer header type (XRA) Guy Harris (Dec 01)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 04)
- Re: Request for link-layer header type (XRA) Guy Harris (Dec 04)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 05)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 11)
- Re: Request for link-layer header type (XRA) Guy Harris (Dec 11)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Dec 12)