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Re: [OPSAWG] [pcap-ng-format] draft-gharris-opsawg-pcap.txt --- FCS length description

Michael Richardson <mcr+ietf@sandelman.ca> Tue, 22 December 2020 16:40 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Guy Harris <gharris@sonic.net>
cc: Pcap-ng file format <pcap-ng-format@winpcap.org>, opsawg@ietf.org, tcpdump-workers <tcpdump-workers@lists.tcpdump.org>
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Date: Tue, 22 Dec 2020 11:40:47 -0500
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Subject: Re: [OPSAWG] [pcap-ng-format] draft-gharris-opsawg-pcap.txt --- FCS length description
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<#secure method=pgp mode=sign>

Guy Harris <gharris@sonic.net> wrote:
    > a 6-bit "extension" field, storing information about the
    > capture, such an indication of whether the packets include an
    > FCS and, if so, how many bytes of FCS are present.

    > So what NetBSD had was a convention where a capture file could have a
    > link-layer type that combined an AF_ value with some additional bits to
    > distinguish the value from a regular LINKTYPE_ value; I don't know what
    > AF_ values they supported for that, or where that code was, or whether
    > it's still supported.

Wow, lots of ill-defined complexity here.

I think that we should just regard this as water under the bridge.
If NetBSD wants to propose a use for those empty bits, then a new
specification could update that use case.

--
Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide

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