Re: [squid-users] tos - setsockopt() problem

From: Henrik Nordstrom <[email protected]>
Date: Sat, 19 Feb 2005 16:22:24 +0100 (CET)

On Thu, 17 Feb 2005, lartc@manchotnetworks.net 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
Received on Sat Feb 19 2005 - 08:22:26 MST

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