IFMCSTAT(8)		  BSD System Manager's Manual		   IFMCSTAT(8)

NAME
     ifmcstat — dump multicast group management statistics per interface

SYNOPSIS
     ifmcstat [-i interface] [-f address-family] [-v] [-K] [-M core]
	      [-N system]

DESCRIPTION
     The ifmcstat command dumps multicast group information from the kernel.

     The following options are supported:

     -i interface
		 specifies the interface to be displayed.

     -f address-family
		 specifies the address family to be displayed; inet, inet6 and
		 link are supported.

     -v 	 specifies that link-layer memberships should be printed; they
		 are suppressed by default.  It may not be specified for -f
		 link.	Source lists for each group will also be printed.

		 If specified twice, and kvm(3) is in use, the control plane
		 timers for each interface and the source list counters for
		 each group will also be printed.

     The following options are only available if ifmcstat has been built with
     support for kvm(3):

     -K 	 attempts to use kvm(3) to retrieve the multicast group infor‐
		 mation.

     -M core	 extracts values associated with the name list from the speci‐
		 fied core, instead of the default /dev/kmem.

     -N system	 extracts the name list from the specified kernel instead of
		 the default, which is the kernel image the system has booted
		 from.

IMPLEMENTATION NOTES
     ifmcstat will always print the embedded scope IDs of IPv6 multicast group
     memberships.  This is because memberships are always scoped to an inter‐
     face.

     When run with the -v option, ifmcstat may print multicast MAC addresses
     twice if they are referenced by a layer 3 protocol.

     When run with kvm(3) support, the names of all interfaces configured in
     the system will be printed in the first column of output, even if no mul‐
     ticast group memberships are present on those interfaces.	The output may
     also be slightly different, as the kernel data structures are being tra‐
     versed with minimal post-processing of the output.

     When built without kvm(3) support, the information displayed by ifmcstat
     is more limited.  This support is recommended for debugging purposes.  It
     requires super-user privilege if used to inspect a running kernel.

SEE ALSO
     netstat(1), getifaddrs(3), getifmaddrs(3), kvm(3)

BSD				 May 27, 2009				   BSD