[tcpdump-workers] Link type FlexRay

Guy Harris guy at alum.mit.edu
Fri Jan 15 15:35:48 EST 2016

On Jan 15, 2016, at 10:44 AM, Guenter Ebermann <guenter.ebermann at googlemail.com> wrote:

> For which type of frame was the LINKTYPE_FLEXRAY 210 allocated?
> The file https://github.com/the-tcpdump-group/libpcap/blob/master/pcap-common.c
> simply state that:
> /*
> * FlexRay automotive bus - http://www.flexray.com/ - as requested
> * by Hannes Kaelber <hannes.kaelber at x2e.de>.
> */
> #define LINKTYPE_FLEXRAY 210
> Also neither tcpdump, nor wireshark contains dissector code to dissect
> this packet.
> I am asking because I want to capture FlexRay frames using custom hardware.
> If no spec. is available I can provide a draft (FlexRay Frame-bitstream as
> captured from the bus + minimal header), example data and a dissector.
> If a spec. is available I will adhere to it.

The thread containing the message in which Hannes requested is at


In the initial message back in 2008, Hannes just said

> we are currently working on the integration of wireshark into our
> datalogger toolchain. For that purpose, we need some new DLT values.
> Since we are capturing automotive busses, such as CAN, Flexray, Most and
>   LIN, I suggest that these busses get there own DLTs.
> I suggest the names

I responded:

> I've assigned those:
> 	DLT_MOST		211
> 	DLT_LIN			212
> If you can indicate what the packet formats would be (assuming it's not 
> obvious from the protocol specifications for those buses - for example, 
> if you add pseudo-headers giving information not available from the raw 
> packet data), that would be helpful, so we don't have different packet 
> formats using the same DLT_ values.

He later responded to me indicating that they were working on the exact format and would probably follow the standard, but I've never received an indication of what the format was.

X2E currently have data logger devices that support FlexRay, such as:


I don't know whether it, or any software that connects to it, supports writing out files in pcap or pcapng format.

I don't know whether Hannes still works at X2E.  You might want to try sending an e-mail to him asking whether a format for DLT_FLEXRAY was ever defined - and, if it has, asking him to send me a copy so that I can add it to the link-layer header types page:


(and, if any of the *others* were defined, to send those to me as well).

If mail to him bounces, you could try contacting X2E to see if that information is available, or if they ever supporting writing out files in pcap or pcapng format.

If they never wrote files out with a link-layer header type of 210 for DLT_FLEXRAY/LINKTYPE_FLEXRAY, then you can use it for your own purposes - send us the spec and I'll add it to the link-layer header types page.

If they did, but they don't tell you what format they use, we can create a new LINKTYPE_/DLT_ value for your format, and provide a public specification for that one.

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