udplite - Lightweight User Datagram Protocol
sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
This is an implementation of the Lightweight User Datagram Protocol (UDP-Lite),
as described in RFC 3828.
UDP-Lite is an extension of UDP (RFC 768) to support variable-length
checksums. This has advantages for some types of multimedia transport that may
be able to make use of slightly damaged datagrams, rather than having them
discarded by lower-layer protocols.
The variable-length checksum coverage is set via a setsockopt(2)
If this option is not set, the only difference to UDP is in using a different
IP protocol identifier (IANA number 136).
The UDP-Lite implementation is a full extension of udp(7)
, i.e., it
shares the same API and API behaviour, and in addition offers two socket
options to control the checksum coverage.
UDP-Litev4 uses the sockaddr_in
address format described in ip(7)
UDP-Litev6 uses the sockaddr_in6
address format described in
To set or get a UDP-Lite socket option, call getsockopt(2)
to read or
to write the option with the option level argument set to
. In addition, all IPPROTO_UDP
socket options are
valid on a UDP-Lite socket. See udp(7)
for more information.
The following two options are specific to UDP-Lite.
- This option sets the sender checksum coverage and takes an
int as argument, with a checksum coverage value in the range
A value of 0 means that the entire datagram is always covered. Values from
1-7 are illegal (RFC 3828, 3.1) and are rounded up to the minimum
coverage of 8.
With regard to IPv6 jumbograms (RFC 2675), the UDP-Litev6 checksum
coverage is limited to the first 2^16-1 octets, as per RFC 3828, 3.5.
Higher values are therefore silently truncated to 2^16-1. If in doubt, the
current coverage value can always be queried using
- This is the receiver-side analogue and uses the same
argument format and value range as UDPLITE_SEND_CSCOV. This option
is not required to enable traffic with partial checksum coverage. Its
function is that of a traffic filter: when enabled, it instructs the
kernel to drop all packets which have a coverage less than the
specified coverage value.
When the value of UDPLITE_RECV_CSCOV exceeds the actual packet
coverage, incoming packets are silently dropped, but may generate a
warning message in the system log.
All errors documented for udp(7)
may be returned. UDP-Lite does not add
Where glibc support is missing, the following definitions are needed:
#define IPPROTO_UDPLITE 136
#define UDPLITE_SEND_CSCOV 10
#define UDPLITE_RECV_CSCOV 11
- basic UDP-Litev4 statistics counters.
- basic UDP-Litev6 statistics counters.
UDP-Litev4/v6 first appeared in Linux 2.6.20.
RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite).
in the Linux kernel source tree
This page is part of release 3.44 of the Linux man-pages
description of the project, and information about reporting bugs, can be found