Installation guide

Note
For more information about Po st Jo in Delay and Po st Fail D elay, refer to the fenced(8)
man page.
3.5.3. Net work Configurat ion
Clicking on the Net wo rk tab displays the Net wo rk Co n f ig u rat io n page, which provides an
interface for configuring the network transport type.
You can use this tab to select one of the following options:
UDP Mu lt icast an d Let Clu st er Ch o o se t h e Mu lt icast Add ress
This is the default setting. With this option selected, the Red Hat High Availability Add-On software
creates a multicast address based on the cluster ID. It generates the lower 16 bits of the address
and appends them to the upper portion of the address according to whether the IP protocol is
IPv4 or IPv6:
For IPv4 — The address formed is 239.192. plus the lower 16 bits generated by Red Hat High
Availability Add-On software.
For IPv6 — The address formed is FF15:: plus the lower 16 bits generated by Red Hat High
Availability Add-On software.
Note
The cluster ID is a unique identifier that cman generates for each cluster. To view the cluster
ID, run the cman_to o l status command on a cluster node.
UDP Mu lt icast an d Sp ecif y t h e Mu lt icast Ad d ress Man u ally
If you need to use a specific multicast address, select this option enter a multicast address into the
Mu lt icast Ad d ress text box.
If you do specify a multicast address, you should use the 239.192.x.x series (or FF15:: for IPv6)
that cman uses. Otherwise, using a multicast address outside that range may cause unpredictable
results. For example, using 224.0.0.x (which is " All hosts on the network") may not be routed
correctly, or even routed at all by some hardware.
If you specify or modify a multicast address, you must restart the cluster for this to take effect. For
information on starting and stopping a cluster with Co n g a, refer to Section 4.4, “Starting,
Stopping, Restarting, and Deleting Clusters” .
Note
If you specify a multicast address, make sure that you check the configuration of routers
that cluster packets pass through. Some routers may take a long time to learn addresses,
seriously impacting cluster performance.
UDP Un icast ( UDPU)
Red Hat Ent erprise Linux 6 Clust er Administ rat ion
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