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Wireshark-bugs: [Wireshark-bugs] [Bug 5696] IEC61850 Sampled Values (sv) dissector issues

Date: Wed, 23 Feb 2011 06:19:58 -0800 (PST)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5696

Steven Blair <ninjadreams@xxxxxxxxx> changed:

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--- Comment #2 from Steven Blair <ninjadreams@xxxxxxxxx> 2011-02-23 06:19:54 PST ---
(In reply to comment #0)

> 1) It assumes that the sampled data in the ASDUs is based on the "PhsMeas1"
> dataset, defined in the "Implementation Guideline for Digital Interface to
> Instrument Transformers using IEC 61850-9-2" document. But this cannot be
> derived from the data captured. Our software sends a different dataset, which
> is now displayed incorrectly. The actual ASN.1 description states that the
> sampled data is of type "OCTET STRING". Further analysis of these octets in a
> generic way is not possible due to the way the protocol works.

Well put - I can confirm this issue.

> 2) The protocol payload length is not set correctly. Our hardware also captures
> the Ethernet CRC32, which is incorrectly assumed to be part of the protocol
> payload (starting a new SV PDU). The dissector should use the value of its
> Length field (sv.length) instead to limit dissection.

My PC's Ethernet interface doesn't pass the CRC bytes to Wireshark, so I can't
confirm this.

I'd also add that Wireshark doesn't seem to support the optional fields in the
ASN.1 specification of an SV frame. These fields are: datset (tag 0x81), refrTm
(tag 0x84) and smpRate (tag 0x86).

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