Re: Request for a new DLT for MTP2 with FCS

[Stephen Donnelly <stephen () endace com>]

On Tue, 2007-02-06 at 18:18 +0100, Florent.Drouin () alcatel-lucent fr
wrote:
>       Hello,

> I need a new datalink value (LINKTYPE_MTP2_FCS) to manage MTP2 frame with
> Checksum.
> (See http://www.wireshark.org/lists/wireshark-dev/200702/msg00206.html )
>
> Once I will have the value, I will provide the patch for libpcap.

Endace DAG cards (for instance) can capture MTP2 with or without FCS,
does your proposal mean that MTP2 without FCS should only use
LINKTYPE_MTP2 and MTP2 with FCS should only use LINKTYPE_MTP2_FCS?

What about other linktypes, such as Ethernet?

The issue of whether captured packets should include FCS and how this is
reported in libpcap seems to be a more generic question. I'm not sure
that duplicating all existing DLTs by adding _FCS (or tripling with
_NOFCS as well) at the end would be accepted by the libpcap community. 

If people are generally happy with adding LINKTYPE_MTP2_FCS as a special
case I have no problem, and Endace can support both linktypes.

Stephen.
-- 
-----------------------------------------------------------------------
    Stephen Donnelly BCMS PhD           email: sfd () endace com
    Endace Technology Ltd               phone: +64 7 839 0540
    Hamilton, New Zealand               cell:  +64 21 1104378
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