First time here? Check out the FAQ!
THIS IS A TEST INSTANCE. Feel free to ask and answer questions, but take care to avoid triggering too many notifications.
0

Why does the PW-MPLS decoder fails in case the encapsulated Ethernat frame has a destination addrss starting with EC:46:70?

Hello Wireshark friends,

The MPLS dissector gets confused in case of MPLS - PW encapsulation, without CW, containing an Ethernet frame, if the destination MAC address of the encapsulated Ethernet Frame corresponds to a Meinberg device, i.e. starts with EC:46:70.

I have to use the Decode As... and select Ethernet PW (no CW).

I am wondering why this happens, what is special in that Meinberg MAC address?

I attached a capture here or screenshot

Please also note that the source MAC address starts with 0x00. I was wondering if this confuses Wireshark as the first 4 bits of that MAC address could be interpreted as CW. However, this might not be the case as Wireshark successfully decodes the last message in my capture where the Destination MAC address is the one starting with 0x00.

Does anyone have any hints, or could point me to the source code of the dissector so I can try to have a look?

Thank you, Andrei

Andrei Spinu's avatar
1
Andrei Spinu
asked 2021-12-15 12:07:02 +0000
grahamb's avatar
23.8k
grahamb
updated 2021-12-15 12:41:16 +0000
edit flag offensive 0 remove flag close merge delete

Comments

I guss if this is consistent it might be a bug. In whic case I would advise to report a bug. Preferably with a capture file that contains just enough data to replicate the issue by others.

hugo.vanderkooij's avatar hugo.vanderkooij (2021-12-15 13:20:19 +0000) edit

This is consistent and can be easily seen by opening the capture. I cheeked on both Windows and CentOS. I am more interested in an explanation than a fix. By the way, is the screenshot visible? The link is: https://drive.google.com/file/d/1Tok5...

Andrei Spinu's avatar Andrei Spinu (2021-12-15 13:26:57 +0000) edit
add a comment see more comments

1 Answer

0

Open issue: 13306: Ethernet-PW-without-CW-over-MPLS packets with first nibbles other than 0 not recognized

Looks like it hasn't been touched in a while. Can you add a comment and link back to this question?

Chuckc's avatar
3k
Chuckc
answered 2021-12-15 17:16:58 +0000
edit flag offensive 0 remove flag delete link

Comments

Thank you for pointing me to the right place! I added a comment to that issue.

Andrei Spinu's avatar Andrei Spinu (2021-12-15 17:26:51 +0000) edit
add a comment see more comments

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account. This space is reserved only for answers. If you would like to engage in a discussion, please instead post a comment under the question or an answer that you would like to discuss.

Add Answer