NAME
ifmcstat —
dump multicast group management
statistics per interface
SYNOPSIS
ifmcstat |
[-i interface]
[-f address-family]
[-v] [-K]
[-M core]
[-N system] |
DESCRIPTION
Theifmcstat command dumps multicast group information
from the kernel.
The following options are supported:
-iinterface- specifies the interface to be displayed.
-faddress-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
-flink. 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 information.
-Mcore- extracts values associated with the name list from the specified core, instead of the default /dev/kmem.
-Nsystem- 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 interface.
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 multicast group memberships are present on those interfaces. The output may also be slightly different, as the kernel data structures are being traversed 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.