Layer 2 Switching Configuration Guide, Cisco DCNM for LAN, Release 6.x
Configuring Link-State Tracking
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Configuring Link-State Tracking

Configuring Link-State Tracking

This chapter describes how to configure link-state tracking on the Cisco Nexus 4000 Series device using Cisco Data Center Network Manager (DCNM) for LAN.


Note


The Cisco NX-OS release that is running on a managed device may not support all the features or settings described in this chapter. For the latest feature information and caveats, see the documentation and release notes for your platform and software release.



Note


Link-state tracking is applicable only for the Cisco Nexus 4000 Series platform, beginning with the DCNM 4.2(3) release.


This chapter includes the following sections:

Information About Link-State Tracking

Link-state tracking, also known as trunk failover, is a feature that binds the link state of multiple interfaces to create redundancy in the network. The feature provides redundancy in the network when used with server network interface card (NIC) adapter teaming. When the server network adapters are configured in a primary or secondary relationship known as teaming and the link is lost on the primary interface, connectivity transparently changes to the secondary interface.

The following figure shows a network configured with link-state tracking. After you enable link-state tracking and create a link-state group, you assign interfaces to the link-state group. Interfaces connected to servers are referred to as downstream interfaces, and interfaces connected to distribution switches and network devices are referred to as upstream interfaces.

When link-state tracking is enabled, the downstream interfaces are bound to the upstream interfaces. After a set of downstream ports are associated to a set of upstream ports, if all of the upstream ports become unavailable, link-state tracking automatically puts the associated downstream ports in an error-disabled state, which causes the primary interface of the server to fail over to the secondary interface.

Figure 1. Typical Link-State Tracking Configuration

The configuration in the preceding figure ensures that when server NIC adapter teaming is used, the traffic flow continues uninterrupted when the uplink connection to a distribution switch is lost. The configuration is as follows:
  • The blade switches in the enclosure are connected to switch 1 and switch 2 through different switches.
  • Link-state group 1 is the primary link from all the blade servers in the enclosure (blade server 1 through blade server n) to switch 1.
  • Link-state group 2 is the secondary (backup) link from all the blade servers to switch 2.

In a link-state group, the upstream ports can become unavailable or lose connectivity because the switch or router fails, the cables are disconnected, or the link is lost. These interactions occur between the downstream and upstream interfaces when link-state tracking is enabled:

  • If any of the upstream interfaces are in the link-up state, the downstream interfaces can change to or remain in the link-up state.
  • If the server detects that the primary link is down, it redirects the traffic to the secondary (backup) link and the secondary link becomes the primary link.

As an example of a connectivity change from link-state group 1 to link-state group 2, when the primary link from blade switch 1 to switch 1 is lost, blade server 1 connects through its secondary Ethernet server interface to blade switch 2 in link-state group 2.

When link-state tracking is disabled, the entire feature is disabled. All the configuration for link-state tracking is removed. The downstream ports revert back to the state when no link-state tracking was set.

You can recover a downstream interface link-down condition by removing the failed downstream port from the link-state group. To recover for multiple downstream interfaces, disable the link-state group.

Licensing Requirements for Link-State Tracking

The following table shows the licensing requirements for this feature:

Product

License Requirement

Cisco DCNM

Link-state tracking requires no license. Any feature not included in a license package is bundled with the Cisco DCNM and is provided at no charge to you.

Cisco NX-OS

Link-state tracking requires an Enterprise Services license. For a complete explanation of the Cisco NX-OS licensing scheme and how to obtain and apply licenses, see the Cisco Nexus 7000 Series NX-OS Licensing Guide, Release 4.2.

Prerequisites for Link-State Tracking

Link-state tracking requires that you configure the logging level in any switch that is used for this feature. The proper logging level ensures that DCNM is synchronized with the link-state tracking status.

To set the proper logging level, enter the following commands:

logging logfile messages 6
logging level lstsvc 4

Note


The logging level lstsvc 4 command can only be used after link-state tracking has been enabled in the switch. Whenever you enable link-state tracking, you must configure these logging-level commands to ensure that DCNM is in sync with the switch for link-state tracking management.


Guidelines and Limitations for Link-State Tracking

Link-state tracking has the following guidelines and limitations:

  • Ethernet 1/1–14 are the designated downstream interfaces.
  • Ethernet 1/15–20 are the designated up stream interfaces.

Note


The Cisco Nexus 4000 Series switch module allows a user to configure a downstream interface as an upstream interface or an upstream interface as a downstream interface. Even though this configuration is allowed in the switch, it is not a valid configuration.

Any attempt to configure an upstream interface as downstream, or a downstream interface as upstream, generates an exception and DCNM displays a warning message. However, DCNM does not prevent a user from proceeding with the incorrect configuration.


Platform Support for Link State Tracking

The following platform supports this feature. For platform-specific information, including guidelines and limitations, system defaults, and configuration limits, see the corresponding documentation.

Platform

Documentation

Cisco Nexus 4000 Series switches

Cisco Nexus 4000 Series switch documentation

Configuring Link-State Tracking

You can access Link-State Tracking from the Switching feature selection. This figure shows how to configure link-state tracking.

Figure 2. Configuring Link-State Tracking

For more information about the Cisco DCNM features, see the Cisco DCNM Fundamentals Guide, Release 5.x.

Enabling Link-State Tracking

You must enable the link-state tracking feature before you can configure any link-state groups.

Procedure
    Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.

    The available devices appear in the Summary pane.

    Step 2   From the Summary pane, click the device on which you want to enable link-state tracking.
    Step 3   From the Details pane, click Enable Link-State Tracking.

    What to Do Next

    Creating a Link-State Group

    Assigning Interfaces to a Link-State Group

    Removing Interfaces from a Link-State Group

    Deleting a Link-State Group

    Creating a Link-State Group

    You can create one or more link-state groups and then assign interfaces to the groups.

    Before You Begin

    Ensure that you have enabled the link-state tracking feature.

    Procedure
      Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.

      The available devices appear in the Summary pane.

      Step 2   From the Summary pane, right-click the device and choose New Group.

      A new row of blank fields appear below the device.

      Step 3   Enter a numerical name for the new group, from 1 to 6, and then press Enter.
      Note   

      If you attempt to enter a name other than a number from 1 to 6, the group field is removed and you must repeat Step 2.

      Blank tables for Upstream Interfaces and Downstream Interfaces display in the Details pane.


      Assigning Interfaces to a Link-State Group

      You can assign a device’s ports as upstream or downstream interfaces in a link-state group.

      Before You Begin

      Ensure that you have enabled the link-state tracking feature and created at least one link-state group.

      Procedure
        Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.
        Step 2   In the Summary pane, click a link-state group to highlight it.
        Step 3   In the Details pane, right-click within the Upstream Interfaces or Downstream Interfaces pane and, from the drop-down list, choose Add Interfaces.

        A dialog box appears, showing the ports that are available to be assigned to this link-state group.

        Step 4   From the Available Ports pane, choose a port to assign to the link-state group. If you want to choose more than one port, press and hold Shift or Ctrl when you click.
        Step 5   Click Add to move the selected port(s) to the Selected Ports pane. Click OK to assign the selected ports. To assign all the available ports to the link-state group, click Add All.

        The dialog box closes and the selected ports appear in the Upstream Interfaces or Downstream Interfaces table.


        Removing Interfaces from a Link-State Group

        You can remove ports that have been assigned to an upstream or downstream interface in a link-state group.

        Before You Begin

        Ensure that you have enabled the link-state tracking feature, created at least one link-state group, and assigned interfaces to the group.

        Procedure
          Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.
          Step 2   In the Summary pane, click a link-state group to highlight it.

          The upstream and downstream interfaces that have been assigned to this link-state group appear.

          Step 3   In the Details pane, click one of the ports in the Upstream Interfaces or Downstream Interfaces table and press Delete. If you want to choose more than one port, press and hold Shift or Ctrl when you click.

          The selected port(s) are removed from the table.


          Deleting a Link-State Group

          You can delete link-state groups. When you delete a link-state group, any interfaces that were assigned to that group become available and can be assigned to another group.

          Procedure
            Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.

            The available devices appear in the Summary pane.

            Step 2   From the Summary pane, right-click the link-state group that you want to delete.
            Step 3   From the drop-down list, choose Delete Link-State Group.

            The link-state group is removed from the Summary pane.


            What to Do Next

            Enabling Link-State Tracking

            Creating a Link-State Group

            Assigning Interfaces to a Link-State Group

            Removing Interfaces from a Link-State Group

            Exporting Link-State Information to Excel

            You can export details about link-state groups to an Excel file (.xls). The information displays in the Excel file similar to the arrangement in the Summary pane, showing the link-state group names, upstream and downstream interfaces, and events.

            Procedure
              Step 1   From the Feature Selector pane, choose Switching > Link-State Tracking.

              The available devices appear in the Summary pane.

              Step 2   Above the Summary pane, click the green arrow.

              The Export to Excel dialog box displays.

              Step 3   Navigate to the location where you want to save the file.
              Step 4   Enter a name for the file and click Save.

              The file is saved to the specified location.


              Field Descriptions for Link-State Tracking

              This section includes the following field descriptions for tunnel interfaces:

              Link-State Summary Pane


              Note


              All fields described in the following table are display only.


              Table 1 Summary Pane

              Field

              Description

              Link-State Group

              Names of devices and the link-state groups within them.

              Interfaces

              Subdivided into Upstream and Downstream and lists the specific interfaces assigned to this link-state group.

              Upstream Status

              Status of whether the upstream switch is up or down. The upstream status is up if at least one upstream interface in that link-state group is up. When all the upstream interfaces in that group are down, this status is down.

              Events

              Cisco DCNM displays a bell icon in the Event column when an event occurs, such as all upstream interfaces in the group going down. If the icon appears, you can click the Event tab to get more details about the event.

              Link-State Group: Details Tab


              Note


              All fields described in the following tables are display only.


              Table 2 Link-State Group: Details—Upstream Interface

              Field

              Description

              Name

              Name of the port.

              Status

              Status of whether the port is up or down.

              Description

              Description of the interface.

              Table 3 Link-State Group: Details—Downstream Interface

              Field

              Description

              Name

              Name of the port.

              Status

              Status of whether the port is up or down.

              Description

              Description of the interface.

              Link-State Additional References

              For additional information related to implementing link-state tracking, see the following sections:

              Link-State Related Documents

              Related Topic

              Document Title

              Link-state tracking configuration

              Cisco Nexus 4001I and 4005I Switch Module for IBM BladeCenter NX-OS Configuration Guide

              Link-state tracking CLI commands

              Cisco Nexus 4001I and 4005I Switch Module for IBM BladeCenter NX-OS Command Reference

              Link-State Standards

              Standards

              Title

              No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

              Feature History for Configuring Link-State Tracking

              This table lists the release history for this feature.

              Table 4 Feature History for Configuring Link-State Tracking

              Feature Name

              Releases

              Feature Information

              Link-State Tracking

              4.2(3)

              This feature was introduced.