Cisco DCNM Interfaces Configuration Guide, Release 4.x
Configuring Fabric Extender
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Configuring Fabric Extenders

Table Of Contents

Configuring Fabric Extenders

Information About Fabric Extenders

Oversubscription

Management Model

Fabric Extender Image Management

Ethernet Interfaces

Licensing Requirements for a Fabric Extender

Prerequisites for Fabric Extenders

Guidelines and Limitations for Fabric Extenders

Configuring a Fabric Extender

Adding a Fabric Extender

Deleting a Fabric Extender

Editing a Fabric Extender

Redistributing the Links

Changing the Number of Links

Maintaining the Pinning Order

Associating a Fabric Extender with an Ethernet Interface

Associating a Fabric Extender

Setting the Ethernet port mode to a Fabric Extender

Associating a Fabric Extender with a Port Channel

Associating a Fabric Extender

Setting the Port Mode to Fabric Extender

Field Descriptions for Fabric Extenders

Fabric Extender Summary Pane

Fabric Extender Details Pane

Additional References

Feature History for Fabric Extender


Configuring Fabric Extenders


This chapter describes how to configure a Fabric Extender on a Cisco NX-OS device.

This chapter includes the following sections:

Information About Fabric Extenders

Licensing Requirements for a Fabric Extender

Prerequisites for Fabric Extenders

Guidelines and Limitations for Fabric Extenders

Configuring a Fabric Extender

Field Descriptions for Fabric Extenders

Additional References

Feature History for Fabric Extender

Information About Fabric Extenders

Beginning with DCNM Release 4.2(1), the Cisco Nexus 2000 Series Fabric Extender works in conjunction with Cisco NX-OS devices to provide high-density, low-cost connectivity for server aggregation. Scaling across 1-Gigabit Ethernet, 10-Gigabit Ethernet, unified fabric, rack, and blade server environments, the Fabric Extender is designed to simplify data center architecture and operations.

The Fabric Extender integrates with its parent switch, the Cisco NX-OS switch, to allow automatic provisioning and configuration taken from the settings on the parent switch. This integration allows large numbers of servers and hosts to be supported using the same feature set as the parent switch, including security and Quality of Service (QoS) configuration parameters, with a single management domain. The Fabric Extender and its parent switch enable a large multipath, loop-free, active-active data center topology without the use of Spanning Tree Protocol (STP).

The Cisco Nexus 2148T Fabric Extender forwards all traffic to its parent Cisco NX-OS switch over 10-Gigabit Ethernet fabric uplinks, allowing all traffic to be inspected by policies established on the Cisco NX-OS switch.

This section includes the following topics:

Oversubscription

Management Model

Fabric Extender Image Management

Ethernet Interfaces

Oversubscription

In a switching environment, oversubscription is the practice of connecting multiple devices to the same interface to optimize port usage. An interface can support a connection that runs at its maximum speed but because most interfaces are not run at their maximum speed, you can take advantage of unused bandwidth by sharing ports. In the case of the Cisco Nexus 2000 Series Fabric Extender, oversubscription, which is a function of the available fabric interfaces to active host interfaces, provides cost-effective scalability and flexibility for Ethernet environments.

The Cisco Nexus 2148T Fabric Extender has 4 10-Gigabit Ethernet fabric interfaces and 48 1000 Base-T Ethernet host interfaces. With this system, you can have any number of configurations. For example, you can configure the following:

No oversubscription (40 host interfaces for 4 fabric interfaces)

1.2 to 1 oversubscription (48 host interfaces for 4 fabric interfaces)

4.8 to 1 oversubscription (48 host interfaces for 1 fabric interface)

Management Model

The Cisco Nexus 2000 Series Fabric Extender is managed by its parent switch over the fabric interfaces through a zero-touch configuration model. The Fabric Extender is discovered by the switch by detecting the fabric interfaces of the Fabric Extender.

After discovery, if the Fabric Extender has been correctly associated with the parent switch, the following actions are performed:

1. The switch checks the software image compatibility and upgrades the Fabric Extender if necessary.

2. The switch and Fabric Extender establish in-band IP connectivity with each other. The switch assigns the Fabric Extender an IP address in the range of loopback addresses (127.0.0.0/8) to avoid conflicts with IP addresses that may be in use on the network.

3. The switch pushes the configuration data to the Fabric Extender. The Fabric Extender does not store any configuration locally.

4. The Fabric Extender updates the switch with its operational status.

Fabric Extender Image Management

No software ships with the Cisco Nexus 2000 Series Fabric Extender. The Fabric Extender image is bundled into the system image of the parent switch. The image is automatically verified and updated (if required) during the association process between the switch and the Fabric Extender.

Ethernet Interfaces

The Cisco Nexus 2148T has 48 1-Gigabit Ethernet host interfaces for its downlink connection to servers or hosts and 4 10-Gigabit Ethernet fabric interfaces with SFP+ interface adapters for its uplink connection to the parent switch.

Licensing Requirements for a Fabric Extender

The DCNM license included with your Cisco NX-OS device covers the use of an unlimited number of Cisco Nexus 2000 Series Fabric Extenders.

Prerequisites for Fabric Extenders

Fabric Extender management has the following prerequisites:

DCNM manages Fabric Extenders running release 4.2 or later releases.

For each managed device that you use DCNM to configure with a Fabric Extender association, ensure that you configure the logging level for fex to 5 (Notifications) or a higher level. To configure the device with the minimal required logging configuration, log into the command-line interface of the device and use the following commands:

switch(config)# logging level fex 5 
switch(config)# logging logfile messages 6 
switch(config)# logging event link-status default

If a Fabric Extender is connected to two NX-OS devices (active-active mode) the NX-OS devices must be synchronized. You can accomplish this by using the same NTP server for both NX-OS devices.

Guidelines and Limitations for Fabric Extenders

Fabric Extender management has the following configuration guidelines and limitations:

Do not connect a bridge or switch to a host interface. These interfaces are designed to provide end host or server connectivity.

The Fabric Extender may connect to the switch through a number of separate physical Ethernet interfaces or at most one port channel interface.

Configuring a Fabric Extender

Figure 8-1 shows the Fabric Extender content pane.

Figure 8-1 Fabric Extender Content Pane

This section includes the following topics:

Adding a Fabric Extender

Deleting a Fabric Extender

Editing a Fabric Extender

Redistributing the Links

Maintaining the Pinning Order

Associating a Fabric Extender with an Ethernet Interface

Associating a Fabric Extender with a Port Channel

Adding a Fabric Extender

You can add a Fabric Extender to the device.

To add a Fabric Extender, follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 From the Summary pane, right-click device.

A drop-down list appears.

Step 3 From the drop-down list, choose New.

Step 4 In the FEX ID field, enter a FEX ID (100-199) and press Enter to deploy the new Fabric Extender.


Deleting a Fabric Extender

You can delete a Fabric Extender from the device.

To delete a Fabric Extender, follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 From the Summary pane, double-click the device to display a list of existing fabric extenders.

Step 3 Right-click the Fabric Extender you want to delete.

A drop-down list appears.

Step 4 From the drop-down list, choose Delete.

A confirmation popup window appears.

Step 5 In the confirmation popup window, click Yes to confirm your Fabric Extender deletion and to deploy your changes to the device.


Editing a Fabric Extender

You can edit the following field values for a Fabric Extender:

Description

Serial Number

Max Pinning Links (see the "Changing the Number of Links" section)

To edit a Fabric Extender, follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 From the Summary pane, double-click the device to display a list of existing fabric extenders.

Step 3 Click the device you want to edit.

Step 4 Enter your changes in the appropriate field.

Once you move out of the edited field, your changes are deployed automatically.


Redistributing the Links

When you provision the Fabric Extender with statically pinned interfaces, the downlink host interfaces on the Fabric Extender are pinned to the fabric interfaces in the order configured initially. If you want to maintain a specific relationship of host interfaces to fabric interface across reboots, you should re-pin the links.

You may want to perform this function in these two situations:

A change in the max-links configuration.

If you need to maintain the pinning order of host interfaces to fabric interfaces.

Changing the Number of Links

If you initially configured port 33 on the parent switch as your only fabric interface, all 48 host interfaces are pinned to this port. If you provision another port, for example 35, then you must perform this procedure to redistribute the host interfaces. All host interfaces are brought down and host interfaces 1 to 24 are pinned to fabric interface 33 and host interfaces 25 to 48 are pinned to fabric interface 35.

To change the number of pinning links, follow these steps:

DETAILED STEPS


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 From the Summary pane, double-click the device to display a list of existing Fabric Extenders.

Step 3 Click the device you want to edit.

Step 4 In the Details pane, enter a new value in the Max Pinning Links field.

Step 5 From the menu bar, choose File > Deploy to apply your changes to the device.


Maintaining the Pinning Order

The pinning order of the host interfaces is initially determined by the order in which the fabric interfaces were configured.

The next time that you reboot the Fabric Extender, the configured fabric interfaces are pinned to the host interfaces in an ascending order by port number of the fabric interface.

To maintain the pinning order, perform the following steps:

DETAILED STEPS


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 Expand the list of Fabric Extenders and select the one you want to edit in the Summary pane.

Step 3 Right-click the Fabric Extender you want to edit.

A drop-down list appears.

Step 4 From the drop-down list, choose Redistribute Pinning.

Cisco DCNM then instructs the device to redistribute pinnings.


Associating a Fabric Extender with an Ethernet Interface

You can associated a Fabric Extender with an Ethernet interface. This section includes the following topics:

Associating a Fabric Extender

Setting the Ethernet port mode to a Fabric Extender

Associating a Fabric Extender

To associate a Fabric Extender follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 Double-click a device to display a list of existing Fabric Extenders.

Step 3 Click the Fabric Extender you want to associate with an Ethernet interface.

Step 4 Display the Association Interfaces pane by hovering your mouse over the Interfaces tab on the Association toolbar to the right of the window.

Step 5 From the Association Interfaces pane, right-click an Ethernet interface.

A drop-down list appears.

Step 6 From the drop-down list, choose Associate FEX.

The Deploying Configuration progress bar appears in the browser window status bar.


Setting the Ethernet port mode to a Fabric Extender

To set the Ethernet port mode to a Fabric Extender follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Ethernet.

The available Ethernet interfaces appear in the Summary pane.

Step 2 Locate the Ethernet interface you want to configure and double-click the Mode field.

The Mode field displays as a drop-down list.

Step 3 To change the port mode, from the Mode drop-down menu choose Fex Fabric.


Associating a Fabric Extender with a Port Channel

You can associate a Fabric Extender with a port channel.


Note You have to associate each Ethernet interface that is a member of the port channel as a fabric interface.


Associating a Fabric Extender

To associate a Fabric Extender with a port channel, follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Fabric Extender.

The available devices appear in the Summary pane.

Step 2 Double-click a device to display a list of existing Fabric Extenders.

Step 3 Click on the Fabric Extender you want to associate with a port channel.

Step 4 Display the Association Interfaces pane by hovering your mouse over the Interfaces tab on the Association toolbar to the right of the window.

Step 5 From the Association Interfaces pane, right-click a port channel.

A drop-down list appears.

Step 6 From the drop-down list, choose Associate FEX.

The Deploying Configuration progress bar appears in the browser window status bar.


Setting the Port Mode to Fabric Extender

To set the port mode to a Fabric Extender, follow these steps:


Step 1 From the Feature Selector pane, choose Interfaces > Port Channel.

The available devices appear in the Summary pane.

Step 2 Double-click a device to display a list of port channels.

Step 3 Click on the port channel you want to configure.

Step 4 In the Port Channels Details pane, click the Port Channel Details tab.

Step 5 Display the Common Settings section.

Step 6 From the Mode drop-down list, choose Fex Fabric.

The Deploying Configuration progress bar appears in the browser window status bar.


Field Descriptions for Fabric Extenders

The following tables describe the Fabric Extender fields in DCNM.

Fabric Extender Summary Pane

Fabric Extender Details Pane

Fabric Extender Summary Pane

Table 8-1

Field
Description

FEX ID

Uniquely identifies a Fabric Extender that is connected to a Cisco NX-OS device.

Description

Description configured for the Fabric Extender.

Serial Number

Configured serial number.

Note If this configured serial number and the actual s/n of the Fabric Extender are not the same the Fabric Extender will not be active.

Max Pinning Links

An integer value that denotes the maximum pinning uplinks of the Fabric Extender that will be active at a time.

FEX Status

Status of the Fabric Extender

Events

Any syslog event that pertains to the Fabric Extender are captured by DCNM and a bell symbol is put in the Events column for that Fabric Extender. To view a specific event, open the Events tab in the details pane.


Fabric Extender Summary Pane

Fabric Extender Details Pane

Table 8-2 Fabric Extender Details Pane

Field Name
Description

General Section

FEX ID

Uniquely identifies a Fabric Extender connected to a Cisco NX-OS device.

Description

Description configured for the Fabric Extender.

Serial Number

Configured serial number.

Note If this configured serial number and the actual serial number of the Fabric Extender are not the same, the Fabric Extender will not be active.

Max Pinning Links

An integer value that denotes the maximum pinning uplinks of the Fabric Extender that will be active at a time.

FEX Status

Status of the Fabric Extender.

Uplink Status Section

Uplink-ID

Uplink port number of the Fabric Extender.

Fabric Port Name

Name of the Cisco NX-OS device port used for the Fabric Extender uplink.

Fabric Port Channel Name

If the fabric port is a member of a port channel, the port channel name is displayed.

Pinned Downlink Interfaces

Satellite port names whose traffic is carried over this uplink.


Additional References

For additional information related to implementing Fabric Extenders see to the Cisco Nexus 2000 Series Fabric Extender Software Configuration Guide.

Feature History for Fabric Extender

Feature Name
Releases
Feature Information

DCNM support for the Fabric Extender

4.2

DCNM support added in this release.