DSCP Tagging missing

[safhdev]

Hello everyone,

so I got 2 CRS312-4C-8XG and I noticed that sometimes qos packets under some circumstances are goingt “normally” thru this Switches.
I checked with ntopng if its just a “I feel it” thing or is it really happening and unfurtanatly I can now say that packages through this switches are missing the DSCP Tagging.
All packets comming from the clients over this switches are always CS0 even the Client / Program tagges them with EF or CS7.
Do I need to configure something in Router OS so the tagging stays on?

[sindy]

In my understanding of the universe, it would be a serious bug if a switch would modify the contents of the frame beyond the L2 header without being explicitly told so. So the first thing to show is the export of your configuration, with any private information like passwords, secrets, private keys, user names, public or global addresses replaced by some xxxxx strings while preserving the consistency of information (i.e. all addreses from one subnet should have the same aaa.aaa.aaa prefix, all addresses from another subnet a bbb.bbb.bbb one etc.).

[safhdev]

In my understanding of the universe, it would be a serious bug if a switch would modify the contents of the frame beyond the L2 header without being explicitly told so. So the first thing to show is the export of your configuration, with any private information like passwords, secrets, private keys, user names, public or global addresses replaced by some xxxxx strings while preserving the consistency of information (i.e. all addreses from one subnet should have the same aaa.aaa.aaa prefix, all addresses from another subnet a bbb.bbb.bbb one etc.).

would you kindly tell me how to export then?

[safhdev]

In my understanding of the universe, it would be a serious bug if a switch would modify the contents of the frame beyond the L2 header without being explicitly told so. So the first thing to show is the export of your configuration, with any private information like passwords, secrets, private keys, user names, public or global addresses replaced by some xxxxx strings while preserving the consistency of information (i.e. all addreses from one subnet should have the same aaa.aaa.aaa prefix, all addresses from another subnet a bbb.bbb.bbb one etc.).

I also double checked and even the packet trace shows a CS0 on the Interface of this switch, so the dscp is infact missing.
I set the qos-trust-l2 and l3 for all ports to “keep” but no change

[safhdev]

In my understanding of the universe, it would be a serious bug if a switch would modify the contents of the frame beyond the L2 header without being explicitly told so. So the first thing to show is the export of your configuration, with any private information like passwords, secrets, private keys, user names, public or global addresses replaced by some xxxxx strings while preserving the consistency of information (i.e. all addreses from one subnet should have the same aaa.aaa.aaa prefix, all addresses from another subnet a bbb.bbb.bbb one etc.).

I also double checked and even the packet trace shows a CS0 on the Interface of this switch, so the dscp is infact missing.
I set the qos-trust-l2 and l3 for all ports to “keep” but no change

actually I guess this fixed it partially. The dscp is now on the packets but the program in question not tagging the packets. I checked it via wireshark the dscp is always cs0 from this program which should be cs5 or cs7.
I will contact the support tomorrow. Thanks you very much for your Input.

[sindy]

Great that you have found the issue elsewhere, but please be aware that a packet trace on the switch cannot show you how the packets looked on the wire, because the CPU recording the trace can only see the frames after they passed through the switch chip, so some switch chip rules may have already modified them.

[safhdev]

Great that you have found the issue elsewhere, but please be aware that a packet trace on the switch cannot show you how the packets looked on the wire, because the CPU recording the trace can only see the frames after they passed through the switch chip, so some switch chip rules may have already modified them.

thanks for the info but to avoid this i started a packet capture on the client and the firewall to exclude a modification from the switch. The switch now should work as intended.

[HarayarWoryar]

The CRS312-4C-8XG switches are not designed to handle high-traffic environments. If you are experiencing problems with DSCP tagging, it may be because the switches are overloaded.
The CRS312-4C-8XG switches are not compatible with all DSCP tagging schemes. If you are having problems with DSCP tagging, you may need to change the DSCP tagging scheme that you are using.