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On 05/05/2020 21:44, Gert Doering wrote:
>> We should print "PW Ethernet Control Word" and the "Sequence Number", 2 last
>> 2 octets of the 4.
>> Like:
>> PW Ethernet Control Word, Sequence Number xxx
> I think we should only print this if "-v" is given. Most of the time,
> both control word and sequence number are of little interest.
>
> I really like tcpdump's very compact "only the most relevant info" output
> format (by default).
OK for "-v" only print.
Other information from Francesco Fondelli:
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it is a bit more complicated than that, look for
/*
* No, there isn't, so use the 1st nibble logic (see BCP 4928,
* RFC 4385 and 5586).
*/
in
https://code.wireshark.org/review/gitweb?p=wireshark.git;a=blob;f=epan/dissectors/packet-mpls.c;h=4ecb10d1216077b92e6d4ca2520340cf053414f4;hb=HEAD
and also the PW ETH heuristic in looks_like_plain_eth
https://code.wireshark.org/review/gitweb?p=wireshark.git;a=blob;f=epan/dissectors/packet-pw-eth.c;h=aec7b662d38ddb36514ed3c213df47ad53ad610b;hb=HEAD
Wireshark MPLS heuristic is not perfect and has been criticized but is still
there :-) hopefully
correctly parsing your data as well.
For tcpdump maybe a -T based approach is better?
-T mpls (+ 1st nibble logic for IPv4/IPv6)
-T ethpw
-T ethpwnocw
...
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Probably some more work to do...
And probably linked to https://tools.ietf.org/html/rfc8469.
--
Francois-Xavier
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