tcpdump mailing list archives
Re: Request for link-layer header type (XRA)
From: Bruno Verstuyft <bruno.verstuyft () gmail com>
Date: Mon, 11 Dec 2017 10:47:38 +0100
Updated the specification with clarifications below. 2017-12-05 13:47 GMT+01:00 Bruno Verstuyft <bruno.verstuyft () gmail com>:
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. 5.2.1.1.3.1 Downstream Data Forwarding in a MAC Domain: A MAC Domain provides downstream DOCSIS data forwarding service using the set of downstream channels associated with the MAC Domain. Each downstream channel in a MAC Domain is assigned an 8-bit Downstream Channel ID (DCID).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.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. 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. Subslot ID: A minislot can be divided into multiple subslots to provide multiple transmission opportunities for Bandwidth requests (see PHY 8.2.4.1 Subslot Structure). This is the ID of this subslot. The leftmost subslot has id 0.Does the SID TLV contain the Service Identifier for the service flow in which the packet was sent?YesDoes the IUC TLV contain the Interval Usage Code for the burst if the packet is a burst?Yes
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Current thread:
- Re: Request for link-layer header type (XRA), (continued)
- Re: Request for link-layer header type (XRA) Guy Harris (Nov 16)
- Re: Request for link-layer header type (XRA) Bruno Verstuyft (Nov 21)
- 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)