Configuring communication between core groups that are in the same cell

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

  1. 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:
    1. In the administrative console, click Servers > Core groups > Core group bridge settings > Access point groups > New.
    2. Enter a name for the access point group that is unique within the cell.
    3. 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:
    1. In the administrative console, click Servers > Core groups > Core group bridge settings. Your current configuration with any existing access point groups is displayed.
    2. 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.
    3. Click Access point groups > access_point_group_name > Core group access points.
    4. 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.
  2. 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:
    1. In the administrative console, click Servers > Core groups > Core group bridge settings > Access point groups > access_point_group_name > Core group access points.
    2. Click a core group access point in the access point group. Click Show Detail.
    3. To create a new bridge interface, click Bridge interfaces > New.
    4. 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.
    5. Consider creating at least two bridge interfaces for each access point. If one bridge interface fails, the other can still be active.
    6. Repeat these steps to create bridge interfaces for each core group access point in your access point group.
  3. 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 6.0.2.31 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.

    1. Shut down all core group bridges in all of your core groups.
    2. Repeat the following actions for each core group in each of your cells:
      1. In the administrative console, click Servers > Core Groups > Core group settings > core_group_name > Custom properties.
      2. Specify IBM_CS_HAM_PROTOCOL_VERSION in the Name field, and 6.0.2.31 in the Value field.
      3. Save your changes.
    3. Synchronize your changes across the topology.
    4. 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. 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:

  1. 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.
  2. 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.
    Core group access points contain 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.



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Last updated: Aug 29, 2010 9:31:45 PM CDT
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