DSCP Classify - a service for applying DSCP to connections

In SQM setup those two parameters correspond to the following options

Squash DSCP on inbound packets (ingress) = squash_dscp
Ignore DSCP on ingress = squash_ingress

You're correct, setting squash_dscp to 0 (allow) is equivalent to nowash in iqdisc_opts.

Enabling squash/wash has the effect of making cake overwrite the DSCP to 0 after passing through the tc qdisc, however DSCP classify would re-apply it from the conntrack for lan bound packets.

squash_ingress doesn't seem to actually do anything in my testing this morning. *Edit: per @moeller0's note below this is because I'm specifying a diffserv in my qdisc_opts.

Washing on WAN egress via eqdisc_opts would make sure your DSCPs are all set to CS0 when sent to your ISP after passing through the qdisc - that could be beneficial depending on how your ISP handles different DSCP marks.