> At 09:21 AM 9/10/2002 +0800, Jason Gao wrote: > >I mean it did not prohibit the use of one bit in the traffic class octet > >for control purpose. > > actually, it very explicitly did. At the top of page 8, it says: > > Implementors should note that the DSCP field is six bits wide. DS- > compliant nodes MUST select PHBs by matching against the entire 6-bit > DSCP field, e.g., by treating the value of the field as a table index > which is used to select a particular packet handling mechanism which > has been implemented in that device. > > The other two bits are defined by RFC 3168. > > You don't get to pull a bit out for your private use. > It is still not a requirement that every node in the Internet must be DS-compliant. Jason