tcpdump mailing list archives
Re: Request for a new DLT for MTP2 with FCS (repost)
From: Florent.Drouin () alcatel-lucent fr
Date: Fri, 16 Feb 2007 13:31:26 +0100
Hello, As requested few days before, I would like to use a new DLT to distinguish between MTP2 without FCS (the current DLT_MTP2) and MTP2 with FCS. This new DLT would be used to validate the FCS, and so to identify "noise", or damaged frames, due to bad transmission. As I did not find an other way to identify mtp2 frames with FCS, specially in case of malformed frame, I think this could be a valuable argument to introduce a new DLT. Once selected on the capture device, this DLT will be used for all the frames captured. So we should not have the problem encountered with the Ethernet datalink, where the FCS are sometimes present, sometimes not. This patch do not change the behaviour of ERF_FCS_BITS, so it preserves the backward compatibility. But now, if the variable ERF_FCS_BITS is not defined, and only in this case, the length of the FCS will be determined according to the linktype. This has the advantage to be easier for the user, and for the wireshark mtp2 dissector. You just have to choose the datalink, and libpcap will produce the corresponding format, that can be fully decoded by wireshark ( I will provide the modification needed for the MTP2 dissector to decode the FCS). The patch is a zipper tar file, based of libpcap-2007.02.12 (See attached file: mtp2_fcs_diff.zip) Best regards Florent
Attachment:
mtp2_fcs_diff.zip
Description:
- This is the tcpdump-workers list. Visit https://cod.sandelman.ca/ to unsubscribe.
Current thread:
- Re: Request for a new DLT for MTP2 with FCS (repost) Florent . Drouin (Feb 16)
- Re: Request for a new DLT for MTP2 with FCS (repost) Guy Harris (Feb 18)
- Re: Request for a new DLT for MTP2 with FCS (repost) Florent . Drouin (Feb 19)
- Re: Request for a new DLT for MTP2 with FCS Stephen Donnelly (Feb 19)
- Re: Request for a new DLT for MTP2 with FCS Florent . Drouin (Feb 19)
- Re: Request for a new DLT for MTP2 with FCS (repost) Florent . Drouin (Feb 19)
- Re: Request for a new DLT for MTP2 with FCS (repost) Guy Harris (Feb 18)