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UDPLITE(7)                 Linux Programmer's Manual                UDPLITE(7)

NAME
       udplite - Lightweight User Datagram Protocol
SYNOPSIS
       #include <sys/socket.h>
       sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
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  sockaddr_in  address  format described in ip(7).
       UDP-Litev6 uses the sockaddr_in6 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
       IPPROTO_UDPLITE.  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.
       UDPLITE_SEND_CSCOV
              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).
       UDPLITE_RECV_CSCOV
              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 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 IPPROTO_UDPLITE     136
           #define UDPLITE_SEND_CSCOV  10
           #define UDPLITE_RECV_CSCOV  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)