NAME
udplite - Lightweight User Datagram Protocol SYNOPSIS
#include
sockfd = socket(AFINET, SOCKDGRAM, IPPROTOUDPLITE); DESCRIPTION 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) option. 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. Address format
UDP-Litev4 uses the sockaddrin address format described in ip(7).
UDP-Litev6 uses the sockaddrin6 address format described in ipv6(7). Socket options
To set or get a UDP-Lite socket option, call getsockopt(2) to read or setsockopt(2) to write the option with the option level argument set to IPPROTOUDPLITE. In addition, all IPPROTOUDP socket options are valid
on a UDP-Lite socket. See udp(7) for more information.
The following two options are specific to UDP-Lite. UDPLITESENDCSCOV This option sets the sender checksum coverage and takes an int as argument, with a checksum coverage value in the range
0..2^16-1. 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 check‐
sum 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 getsockopt(2). UDPLITERECVCSCOV
This is the receiver-side analogue and uses the same argument format and value range as UDPLITESENDCSCOV. 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 UDPLITERECVCSCOV exceeds the actual packet coverage, incoming packets are silently dropped, but may gener‐ ate a warning message in the system log. ERRORS
All errors documented for udp(7) may be returned. UDP-Lite does not add further errors. FILES
/proc/net/snmp - basic UDP-Litev4 statistics counters.
/proc/net/snmp6 - basic UDP-Litev6 statistics counters. VERSIONS
UDP-Litev4/v6 first appeared in Linux 2.6.20. BUGS Where glibc support is missing, the following definitions are needed:
#define IPPROTOUDPLITE 136
#define UDPLITESENDCSCOV 10
#define UDPLITERECVCSCOV 11 SEE ALSO ip(7), ipv6(7), socket(7), udp(7)
RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite). Documentation/networking/udplite.txt in the Linux kernel source tree COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-12-03 UDPLITE(7)