Use this task to configure communication between core groups
that are in the same cell.
Before you begin
Configure two core groups with application servers that
are in the same cell.
About this task
A cell, by default, contains a single core group, called
DefaultCoreGroup. All processes in the cell are initially members
of this core group. A single core group is usually sufficient. However,
some topologies or special circumstances require multiple core groups.
For example, the optimal number of servers in a core group is typically
around 50. If the number of members in a core group exceeds this optimal
number, you might need to create one or more additional core groups.
If
you need to define multiple core groups within a cell, you should
configure core group bridges between those core groups. If you do
not configure these core group bridges, each core group is isolated
from the other core groups in the cell.
After you configure
the core group bridges between the core groups in a cell, each core
group member can use the bridges to share its availability status
with all of the other members of the configured core groups in that
cell.
Avoid trouble: When
configuring core group bridges, remember the following requirements:
- Whenever a change is made in core group bridge configuration,
including the addition of a new bridge, or the removal of an existing
bridge, you must fully shutdown, and then restart all core group bridges
in the affected access point groups.
- There must be at least one running core group bridge in
each core group. If you configure two bridges in each core group,
a single server failure does not disrupt the bridge functionality.
Also, configuring two bridges enables you to periodically cycle out
one of the bridges. If all the core group bridges in a core group
are shutdown, the core group state from all foreign core groups is
lost.
gotcha
Best practice: It
is also recommended that:
- Core group bridges be configured in their own dedicated server
process, and that these processes have their monitoring policy set
for automatic restart.
- For each of your core groups, you set the IBM_CS_WIRE_FORMAT_VERSION
core group custom property to the highest value that is supported
on your environment.
- To conserve resources, do not create more than
two core group bridge interfaces when you define a core group access
point. You can use one interface for workload purposes and another
interface for high availability. Ensure that these interfaces are
on different nodes for high availability purposes. For more information,
see the frequently asked question information on core group bridges.
bprac
Complete the following actions to configure communication
between core groups that are in the same cell.
Procedure
- Configure an access point group to define the core groups
that need to communicate. An access point group contains
the core group access points for the core groups that need to communicate.
Core group access points define the set of servers that provide access
to the core group. To configure communication between core groups
that are in the same cell, you can choose an existing access point
group or create a new access point group. To create an access point,
complete the following steps:
- In the administrative console, click Servers > Core
groups > Core group bridge settings > Access point groups > New.
- Enter a name for the access point group that is unique
within the cell.
- Add core group access points to your access point group.
Choose any available core group access points for the core groups
that need to communicate in the cell. A default core group access
point is created whenever a core group is created. The access point
group that you create must have a core group access point for each
core group in the cell.
Restriction: Do not add any peer access points.
Add peer access points only if you are configuring communication with
a core group in a different cell. If you need to communicate with
core groups that are outside of the cell, you must create another
access point group that has one core group access point and one or
more peer access points.
If you use an existing
access point group, choose an access point group that does not have
peer access points. To configure an existing access point group, perform
the following steps:
- In the administrative console, click Servers > Core
groups > Core group bridge settings. Your current
configuration with any existing access point groups is displayed.
- Verify that the access point group does not have any
peer access points. Peer access point groups are used
for communication between core groups in different cells. Click the
access point group you want to configure and ensure that no peer access
points are listed.
- Click Access point groups > access_point_group_name >
Core group access points.
- Add core group access points to your access point group.
Choose any available core group access points for the core groups
that need to communicate. The access point group you create should
have a core group access point for each core group in the cell.
- Create bridge interfaces for each core group access point.
The bridge interfaces that you add provide access to the core group.
Create at least one bridge interface for each core group access
point. To provide high availability for the core group access point,
configure two or more bridge interfaces. If a core group has multiple
core group access points, each core group access point must contain
the same number of bridge interfaces for the same set of servers.
To configure bridge interfaces, perform the following steps:
- In the administrative console, click Servers > Core
groups > Core group bridge settings > Access point groups > access_point_group_name >
Core group access points.
- Click a core group access point in the access point
group. Click Show Detail.
- To create a new bridge interface, click Bridge interfaces
> New.
- Select a node, server, and transport channel chain combination
for the bridge interface. Click OK. All the bridge
interfaces for the core group access points that are in the same access
point group must have transport channel chains with the same port
name. You can configure the same port name by selecting the same chain
name for all of the bridge interfaces. The transport channel chain
can be the DCS or DCS-secure channel chains that are created for the
DCS_UNICAST_ADDRESS transport chain.
- Consider creating at least two bridge interfaces for
each access point. If one bridge interface fails, the other can still
be active.
- Repeat these steps to create bridge interfaces for each
core group access point in your access point group.
- Optional: Configure the high
availability manager protocol to establish transparent bridge failover
support.
During core group bridge state rebuilds, cross-core
group state can be moved between running bridges. This situation
might cause the data to be temporarily unavailable until the bridge
has completed the rebuild process.
If
you are running on Version 6.1.0.19 or later, set the IBM_CS_HAM_PROTOCOL_VERSION
core group custom property to 6.0.2.31 for
all of your core groups to avoid a possible high availability state
outage during core group bridge failover. When this custom property
is set to 6.0.2.31, the remaining bridges recover
the high availability state of the failed bridge without the data
being unavailable in the local core group.
Complete the following
actions to set the IBM_CS_HAM_PROTOCOL_VERSION core group custom property
to 6.0.2.31 for all of your core groups.
- Shut down all core group bridges in all of your core
groups.
- Repeat the following actions for each core group in
each of your cells:
- In the administrative console, click core_group_name >
Custom properties.
- Specify IBM_CS_HAM_PROTOCOL_VERSION in
the Name field, and 6.0.2.31 in
the Value field.
- Save your changes.
- Synchronize your changes across the topology.
- Restart all of the bridges in the topology.
All of the core groups within this topology are using
the 6.0.2.31 high availability manager protocol.
Results
The core groups that are in the same cell and configured in
an access point group can communicate.
Example
In the cell_x cell, there are the x_core_group_1, x_core_group_2,
and x_core_group_3 core groups. Each core group already has
a core group access point. The following image illustrates an access
point group between the core groups in the cell_x cell and
an example of the configuration in the administrative console.
Figure 1. Three core group access points in the same cell belong to the
same access point group.

Perform the following
steps to configure communication between the three core groups in
the cell_x cell:
- Create the x_access_point_group access point
group. Add a core group access point to the access point group for
each core group that is in the cell. In this example, add the x_core_group_ap_1 , x_core_group_ap_2,
and x_core_group_ap_3 access points to the x_access_point_group access
point group.
- Create bridge interfaces for each core group access point. The
following diagram illustrates the bridge interfaces for thex_core_group_ap_2 core
group access point:
Figure 2. Core group access points contain one
or more bridge interfaces.
By creating an access point group and adding all core groups
in the cell to the access point group, you enabled communication between
all the core groups that are in the cell_x cell.
What to do next
You can configure this cell to communicate with core groups
in other cells.