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 from UDP is  in
       using a different IP protocol identifier (IANA number 136).

       The  UDP-Lite implementation is a full extension of udp(7)--that is, it
       shares the same API and API behavior, 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 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2014-07-08			    UDPLITE(7)