Wireshark-dev: [Wireshark-dev] Undissected reserved fields
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From: Dario Lombardo <dario.lombardo.ml@xxxxxxxxx>
Date: Fri, 27 Feb 2015 17:40:27 +0100
I'm playing with the "undissected bytes" functionality of wireshark, patching some dissectors that clearly lack some fields. But now I've found some of them that fall in a "grey area" and I'd lilke to discuss with other devels the best way to go on.

I've found that many dissectors lack decoding of "reserved/unused" fields. An example of them is the ISL dissector and an example file is provabis.pcap (found it in the wiki). 
This field is reserved but is part of the specifications of the protocol (have a look here http://www.cisco.com/c/en/us/support/docs/lan-switching/8021q/17056-741-4.html). It is clearly stated that the field is 0x0 in ethernet, but can have values in token ring or FDDI. 

So the general question is: is it correct to leave "reserved/unused" fields udecoded? Or would it better to decode them as described in the actual specifications (reserved of unused)?

Thanks for sharing your point of view!!
Dario.