Configuring a stack

Use the STACKING widget to configure the stack.

Before you begin

If an appliance contains capture data that is not relevant to the stack that you are adding it to, remove the captured data from the appliance before adding it to the stack.

About this task

The STACKING widget displays the configuration of the stack. The following image shows a stack that is fully configured and capturing data:
Figure 1. Configuring a stack
The Stacking window shows fields for the Stack name/UUID, Role, State, Operational Status, Capturing state, Location, Type, Version, Host, and first and last packet timestamps. Each entry in the stack has buttons to Standby, and Remove the stack member, and Unexpect for the Stack Nodes. Below this are fields to specify a new Stack Controller (and name), and a new Stack Node (and name).

Only one appliance at a time is capturing data. As the appliance fills up with capture data, a different appliance in the stack becomes the Storing appliance.

The order in which appliances are enabled for capture is random. Neither the order of devices in the STACKING widget view or the physical cabling influences the selection order. However, when all appliances in the stack hold capture data, the next capturing device is always the appliance that holds capture data with the oldest timestamp.

Procedure

  1. Click the ADMIN tab and go to the GROUP MEMBERSHIP widget. Verify that all appliances for the stack are correctly grouped.
  2. Assign a Stack Controller and create the stack:
    1. In the STACKING widget, in the Stack Controller list, select the appliance that you want to be the Stack Controller.

      The stack name is used only to uniquely identify the stack, and is not used anywhere else in the configuration.

    2. In the Name of new stack field, type a descriptive name for the Stack Controller, and then click New Stack.

      The new stack is created and appears as a new entry in the STACKING widget.

  3. Add stack nodes to the stack:
    1. In the Unit to add list box, select the appliance that you want to add to the stack.
    2. In the Stack list, select the name of the stack that you want to add the appliance to, and click Add Stack Node.

      If a group contains multiple stacks, ensure that you select the correct stack name from the menu.

    3. Repeat these steps for each appliance that you want to add to the stack.

      When all appliances are added, the stack should appear healthy and ready to enable data capture.

    Note: When you add Stack Nodes, the operational status of the STACKING widget might show temporary Operational Status errors. This happens because connectivity in the stack ring is incomplete until all Stack Nodes are added.
  4. Verify the stack configuration:
    1. Select the stack and verify that the list of appliances is as expected for the stack.
    2. Check that each appliance in the stack has the same version number and displays the following values:
      • Operational Status = OK
      • State = In Service

      You are now ready to enable data capture.

  5. Turn on data capture:
    1. Click Expect next to each Stack Node in the stack to enable the appliance for data capture.
      Note: By default, all Stack Nodes are set to Unexpect when they are first added to the stack to prevent an appliance storing captured data until it is physically enabled.
    2. Go to the GROUP MEMBERSHIP widget, and click Switch To for the relevant Stack Controller.
    3. Go to Traffic Capture in the CONTROL widget, and click Turn On to start capturing data.
    4. Click the DASHBOARD tab for the Stack Controller to check for ingress traffic.

      Port 2 of the Stack Controller is the TAP port for the stack. If there is ingress traffic on this port, you see:

      1. The traffic pattern matches the ingress traffic.
      2. The traffic pattern on the Stack Controller dashboard for all Stack Nodes is twice the size of the ingress traffic (plus a number of 64-127 bytes unicast packets).
        Note: The ingress traffic is transmitted to all appliances in the stack, but in both directions (clockwise and counterclockwise) on port 0 and port 1. At the same time, a proprietary stack protocol is running that continuously carries several small frames across the ring.
  6. Check the capture data in the STACKING widget:
    1. Check the appliances in your stack, and find the appliance whose Capturing column shows a value of Storing.

      Only one appliance at a time is capturing data, therefore, only one appliance shows Storing and all other appliances are idle.

    2. On the appliance that is capturing data, check that the First packet and Last packet columns show valid timestamp values.

      As the appliance fills up with capture data, a different appliance in the stack becomes the Storing appliance, and the First packet and Last packet timestamps for the new appliance are updated.