Use of "from-dscp-high-3-bits" in 6.xx

RouterOS General
1

Can someone explain the advantage (or a link) of using dscp-from-high-bit-3 in 6.xx compared to standar use of “Set priority” with DSCP in 5.xx?
I have read the Wiki documentation but I can not find the advantage

Thanks

2

check the slide of MUM Venice 2014, some nice feature…

3

thanks. I did not find exactly a response to my question in this MUM.
Someone knows the answer to my question? or where is a article that explain it?

4

please, someone?

5

I know this is an old post, but there is a difference, and it is not well documented, so it is worth explaining here:

new-priority=from-dscp sets priority value 0-63 from DSCP (essentially copies the 0-63 DSCP value to a 0-63 priority value without alteration); these priority values 0-63 can be used by following mangle rules. Once all the mangle rules have been processed, this gets reduced to the 3 low bits (priority value mod 8 ) to get a value between 0 and 7 inclusive, so priority values 0, 8, 16, 24, 32, 40, 48, and 56 are reduced to priority 0, priority values 1, 9, 17, 25, 33, 41, 49, and 57 are reduced to priority 1, etc.
new priority=from-dscp-high-3-bits uses the 3 DSCP high bits to immediately reduce priority to a value between 0 and 7 inclusive, so DSCP values 0-7 are translated to priority 0, DSCP values 8-15 are translated to priority 1, etc.

Usually you would want to use the high 3 bits version. The regular from-dscp requires many other mangle rules to remap priorities correctly, if you leave the default, you end up with usually a nonsensical mapping. It is a common mistake to use from-dscp and no other rules.