The DSCP value of IP packets can be changed by switches offering DiffServ.

DiffServ is a filtering function offered by HiOS 2A, 3S and 3A devices.

The following description is best for the web IF as of HiOS rel. 4.0.02.

To set-up this function:

1. Create a Class with rules to describe your packet, e.g. by destination and/or source address, IP protocol (e.g. TCP or UDP) ...
2. Create a Policy to define what you want to do with the filtered packets, in this case with attribute ""markIpDscpVal"" = ... (whatever value you want)
   In case you also want this packet to be treated with the respective priority at this switch you have to additionally add another attribute ""assignQueue"" with the respective queue ID, else only the following switches in the direction of the destination can evaluate the DSCP value.
3. Assign the Policy to the inbound port
4. Activate DiffServ
5. Check in ""DiffServ - Overview"" the whole settings for DiffServ
6. Store the configuration

Please note that a lot of applications work as dialogue and not as monologue, i.e. also traffic back might might be useful to be prioritized.

Please also note article How can I prioritize packets via the DSCP value of IP?