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.