Re: [6lo] Call for feedback to draft-wachter-6lo-can-00

"Carles Gomez Montenegro" <carlesgo@entel.upc.edu> Sun, 20 October 2019 13:37 UTC

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Date: Sun, 20 Oct 2019 15:37:53 +0200
From: "Carles Gomez Montenegro" <carlesgo@entel.upc.edu>
To: "Alexander Wachter" <alexander@wachter.cloud>
Cc: 6lo@ietf.org
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Subject: Re: [6lo] Call for feedback to draft-wachter-6lo-can-00
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Dear Alexander,

Thanks for your responses.

To some extent, I see similarities between the environment you are
considering (CAN) and MS/TP. Few years ago, the 6Lo WG produced RFC 8163,
which specifies IPv6 over MS/TP.

I understand that using header compression reduces the amount of IPv6
packets that will require fragmentation. Also, it provides a more
efficient use of the bus. Interesting!

Cheers,

Carles


> Dear Carles,
>
> On 17.10.19 18:16, Carles Gomez Montenegro wrote:
>
>  > Thanks for your new Internet Draft submission!
> Thanks for the quick feedback.
>
>  > I have a few clarifying questions:
>  >
>  > - What type of power sources can we expect for CAN devices?
>
> They are usually mains-powered. In the automotive domain, it could be
> that nodes are battery-powered, but the battery is not a constraining
> factor.
>
>  > - What bit rate/rates is/are typical in CAN?
>
> The bit rate depends on the used cables, cable length, environment, ...
> 125 kbaud should work for long lines, 1 Mbaud for classic CAN and short
> lines, and up to 8 Mbaud for CAN-FD.
>
>  > - What kind of errors (e.g. due to BER) can we expect? Would CAN be
>  > categorized as a lossy technology, or rather as a very low error rate
>  > technology (e.g. Ethernet-like)?
>
> Bit errors may occur, but that heavily depends on the wiring and
> environment. Usually, we can expect a low BER [1]. Errors during
> transmission are detected, and the frame is retransmitted automatically.
> All nodes have an error counter and disconnect from the bus when the
> counter exceeds the limit. The bus is hard-wired, and nodes do not
> disappear.
>
> Kind regards,
> Alexander
>
> [1]
> https://pdfs.semanticscholar.org/c16e/1c68ddfe5e525d3e4cc9c3478250f5ad36df.pdf
>
> --
> Alexander Wachter, BSc
>
> Student of Information and Computer Engineering
> Graz University of Technology