IP_TOS(2const)

NAME
IP_TOS - type of service

LIBRARY
Standard C library (libc, -lc)

SYNOPSIS
#include <netinet/in.h>  /* Definition of IP* constants */
#include <sys/socket.h>

int setsockopt(int sockfd, IPPROTO_IP, IP_TOS,
               const int *tos, sizeof(int));
int getsockopt(int sockfd, IPPROTO_IP, IP_TOS,
               int *tos, sizeof(int));

DESCRIPTION
Set or receive the Type-Of-Service (TOS) field that is sent with every IP packet originating from this socket. It is used to prioritize packets on the network.

There are some standard TOS flags defined:

IPTOS_LOWDELAY
    to minimize delays for interactive traffic,

IPTOS_THROUGHPUT
    to optimize throughput,

IPTOS_RELIABILITY
    to optimize for reliability,

IPTOS_MINCOST
    should be used for "filler data" where slow transmission doesn't matter.

At most one of these TOS values can be specified. Other bits are invalid and shall be cleared.

Linux sends IPTOS_LOWDELAY datagrams first by default, but the exact behavior depends on the configured queueing discipline.

Some high-priority levels may require superuser privileges (the CAP_NET_ADMIN capability).

ERRORS
See IPPROTO_IP(2const). See setsockopt(2). See ip(7).

HISTORY
Linux 1.0.

SEE ALSO
IPPROTO_IP(2const), setsockopt(2), ip(7)