I'm currently reading the SWITCH OCG and noticed on P.324 that it says in regards to the cisco-softphone keyword
Packets that are received with with DSCP value of 24, 26, or 46 will be trusted;
But, 24 doesn't appear to be a valid DSCP value. It would equate to AF30 (Flash with Drop Precedence of 0). The book only lists 3 levels of Drop Precedence - 1 (Low), 2 (Medium), and 3 (High). Do they perhaps mean 34 (AF41 / Flash Override with DP of 2)?
