On Thu, 17 Feb 2005, lartc@xxxxxxxxxxxxxxxxxxx wrote:
has anyone noticed on fc3 a tos setsockopt() problem ??
if i try to set tos_outgoing to 0x8 it works just fine. set it to 0xEE and no tos marking happens.
The ToS octet in TCP/IP has a long muddled history, but things have now settled and these days it is 6 bits in size for DS (RFC2474) and the top two bits is used by ECN (RFC3158) and can not be set by applications.
For details see
RFC2474 Definition of the Differentiated Services Field (DS Field) RFC3158 The Addition of Explicit Congestion Notification (ECN) to IP
RFC3158 has some quite interesting reading in section "22. Historical Definitions for the IPv4 TOS Octet" and I recommend to start by reading this.
Regards Henrik
