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)