MRTG-IPV6(1)			     mrtg			  MRTG-IPV6(1)



NAME
       mrtg-ipv6 - IPv6 support in MRTG

OVERVIEW
       MRTG and cfgmaker support SNMP over IPv6. IPv6 targets can be specified
       by hostname or IPv6 address, and if the required libraries are present
       (see below), queries will use IPv6.

USAGE
       Enabling IPv6

       IPv6 is currently disabled by default and must be explicitly enabled.
       In MRTG this is done by turning on the EnableIPv6 global option in the
       configuration file. In cfgmaker, it is enabled with the --enable-ipv6
       command-line option.

       If IPv6 is disabled, MRTG and cfgmaker should behave in exactly the
       same way as previous versions. So the addition of IPv6 support should
       have no effect on existing MRTG setups unless IPv6 is enabled.

       IPv6 support requires the Socket6 and INET6 libraries (see below). If
       MRTG cant find them, IPv6 is disabled.

       Specifying IPv6 targets

       IPv6 targets may be specified by name or IPv6 address. Numeric IPv6
       addresses may be used with both cfgmaker and MRTG, but they must be
       enclosed in square brackets.

       For example, a target could be specified as:

	public@[2001:760:4::]:161

       Hostnames work as expected: first an IPv6 name lookup is tried, then an
       IPv4 lookup.

       Targets that do not support SNMP over IPv6

       Many targets (this currently includes all Cisco routers) do not yet
       support SNMP over IPv6 and must be monitored over IPv4. This can cause
       problems if you specify a target through its DNS name and the name maps
       to both the IPv6 address and the IPv4 address of the target: MRTG will
       only try IPv6, and will fail.

       To query these targets, use the IPv4Only per-target option, which tells
       MRTG not to use SNMP over IPv6 for the target.

       MRTG does not fall back to IPv4 for performance and correctness rea
       sons. If there are many routers to query, a timeout for every router
       would make MRTG take too long to query them all. And if, for some rea
       son, IPv6 connectivity to the target is lost, MRTGs error messages can
       help figure out what is wrong.

       cfgmaker does fall back from IPv6 to IPv4. If IPv6 is enabled and cfg
       maker is given a hostname that resolves to both an IPv6 and an IPv4
       address, it first tries to query the target over IPv6. If it receives
       no answer, it tries again using IPv4. If the target answers, cfgmaker
       sets the IPv4Only option in the generated config file.

IPv6 LIBRARIES
       Libraries required

       IPv6 support requires the Socket6 and INET6 Perl modules. Both can be
       downloaded from CPAN:

       http://search.cpan.org/author/UMEMOTO/Socket6/

       http://search.cpan.org/author/MONDEJAR/INET6/

       If you use Debian, you will need the packages libsocket6-perl and
       libio-socket-inet6-perl, which are (or should soon be) in unstable.

       So far, IPv6 support has been tested on Linux only, and only with
       Socket6 version 0.12. Also note that IPv6 wont work at all if you
       dont have INET6.pm version 2.00 or newer.

       Installing the libraries

       Building and installing Socket6 and INET6 is very simple. For each mod
       ule, just unpack the archive and then do:

	perl Makefile.PL
	make

       and then:

	su
	make install

       If you have installed the libraries successfully, cfgmaker and mrtg
       should automatically detect them and allow IPv6 support to be enabled.

AUTHOR
       Lorenzo Colitti 



2.14.7				  2006-09-06			  MRTG-IPV6(1)