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This web page is no longer maintained. Information presented here exists only to avoid breaking historical links.
The Project stays maintained, and lives on: see the Linux-HA Reference Documentation.
To get rid of this notice, you may want to browse the old wiki instead.

1 February 2010 Hearbeat 3.0.2 released see the Release Notes

18 January 2009 Pacemaker 1.0.7 released see the Release Notes

16 November 2009 LINBIT new Heartbeat Steward see the Announcement

Last site update:
2021-10-22 06:27:46

bcast - configure broadcast communication path

The bcast directive is used to configure which interfaces Heartbeat sends UDP broadcast traffic on. More than one interface can be specified on the line. The udpport directive is used to configure which port is used for these broadcast communications if the udpport directive is specified before the bcast directive, otherwise the default port will be used. A couple of sample bcast lines are shown below.

bcast eth0 eth1  # on Linux systems
bcast le0        # for Solaris systems

On CRM-enabled clusters, the bcast directive does not work on FreeBSD and OpenBSD because of the fragmentation issue described in

W. Richard Stevens - Unix Network Programming - Vol 1 - 3rd Edition: The Sockets Networking API

20.4 dg_cli Function Using Broadcasting
IP Fragmentation and Broadcasts

Berkeley-derived kernels do not allow a broadcast datagram to be fragmented.
If the size of an IP datagram that is being sent to a broadcast address exceeds
the outgoing interface MTU, EMSGSIZE is returned (pp. 233-234 of TCPv2).
This is a policy decision that has existed since 4.2BSD. There is nothing that
prevents a kernel from fragmenting a broadcast datagram, but the feeling is
that broadcasting puts enough load on the network as it is, so there is no need
to multiply this load by the number of fragments.
AIX, FreeBSD, and MacOS implement this limitation. Linux, Solaris, and HP-UX
fragment datagrams sent to a broadcast address. 

This results because CRM clusters try and send large (>MTU size) packets over the cluster communication media.