Hi list, What do you think--how should we go about this?
-J Glattfelder Christoph (glc) wrote: > Hello Jeff > > Unfortunately, a frame must be searched for the trailer to recognize it as > PRP frame. But I see no problem to have it disabled by default. > > > Best regards > > Christoph Glattfelder > > Zürcher Hochschule Winterthur > Institute of Embedded Systems - InES > > Technikumstrasse 9 > Postfach 805 > CH-8401 Winterthur > Tel. +41(0)52 260 69 74 > > [EMAIL PROTECTED] > > > -----Ursprüngliche Nachricht----- > Von: Jeff Morriss [mailto:[EMAIL PROTECTED] > Gesendet: Montag, 16. April 2007 10:26 > An: Developer support list for Wireshark; Glattfelder Christoph (glc) > Betreff: Re: [Wireshark-dev] Parallel Redundancy Protocol (PRP) dissector > > > > Meier Sven (msv) wrote: >> This is a dissector for the Parallel Redundancy Protocol (PRP) defined >> in chapter 6 of the IEC 62439. >> >> PRP uses two independent networks in parallel and allows redundancy >> without switchovers. >> >> The protocol is sending Mac multicast messages with Ethertype 0x88fb. In >> addition to that it adds to every Ethernet frame a 4 byte trailer before >> the FCS. The trailer is detected by checking a size field and an >> identifier which are part of the trailer. Therefore, if the last 4 bytes >> of a frame match a correct trailer they get interpreted as a trailer, >> although it was probably not a real one. > > Is there some way to know if the trailer is going to be there without > searching for it? As it is, registered as a postdissector (didn't even > know those existed until now), this dissector will get called for every > frame--which seems a bit excessive to me. > > If there's no way to know ahead of time, maybe this dissector should be > disabled by default, though I'm not sure how to best go about doing that. > > _______________________________________________ Wireshark-dev mailing list [email protected] http://www.wireshark.org/mailman/listinfo/wireshark-dev
