Let's disable it by default to avoid the overhead of checking every packet.
On Mon, Apr 16, 2007 at 05:53:19PM +0800, Jeff Morriss wrote: > > 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 > > > > Z??rcher Hochschule Winterthur > > Institute of Embedded Systems - InES > > > > Technikumstrasse 9 > > Postfach 805 > > CH-8401 Winterthur > > Tel. +41(0)52 260 69 74 > > > > [EMAIL PROTECTED] > > > > > > -----Urspr??ngliche 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 _______________________________________________ Wireshark-dev mailing list [email protected] http://www.wireshark.org/mailman/listinfo/wireshark-dev
