Fabrics

A fabric is a collection of devices specific to one organization, and each device is specific to a single fabric. A fabric is the configuration and monitoring domain; users configure fabrics, not individual devices. A fabric is also a blueprint to which physical devices are bound and interconnected. The blueprint helps ensure the adhereance to all physical and logical designs.

These are some of the things that you define in a fabric blueprint:​

  • Device model​
  • Number of spine switches, leaf switches, and servers
  • Through which port the devices are connected​
  • VRF instance, VNI, and VLAN configuration​
  • Routing configuration​
  • Target software release for the devices in the fabric​

Designing the fabric blueprint

When you have created a new organization or need to add a fabric to an existing organization, you can use the Blueprint Designer in the Cisco Nexus Hyperfabric to create a blueprint for the new fabric.

Create a fabric without using a template

Follow these steps to create a fabric without using a template.

Step 1

Choose Fabrics.

Step 2

Click + Add new fabric and select New fabric.

  1. If you want to change the fabric name, click edit ( edit ) next to the default name, modify the name, and click Update.

    The name must be unique and can have from 3 to 120 characters. The name can contain a hyphen (-), but no other special characters.

    By default, the fabric has one switch tier.

  2. If you want to upgrade the fabric entitlement level, click Upgrade.

    The fabric's current entitlement level displays to the right of the fabric name. For more information about entitlement levels, see Cisco Nexus Hyperfabric - Subscriptions.

Step 3

Follow these substeps to configure the switch tiers.

  1. If you want to change the default switch tier name, click edit ( edit ) next to the default name, modify the name, and click Update.

    By default, the switch tier has one switch group.

  2. If you want to change the default group name and short name, click edit ( edit ) next to the default name, modify the name and short name, and click Update.

  3. From the drop-down list at the top of the group, select the switch model.

  4. Enter a name for the hardware set and fill out the other fields.

    Cisco Nexus Hyperfabric uses the hardware set name as part of the device name.

    By default, the group has one hardware set. If you want to add another hardware set, click Add hardware set, then repeat this substep.

  5. If you want to add another switch group, click Add group, then repeat substep 3.b and the succeeding substeps.

  6. If you want to add another switch tier, click Add tier, select Switches, and repeat this entire step.

To design a single-switch fabric or a mesh fabric with a switch model, create only one switch group. If you need to add another switch model, add another switch group. For example, you can have two switch groups—one for spine switches and one for leaf switches—to create a spine and leaf topology.

As you make your switch choices, Cisco Nexus Hyperfabric updates the topology.

Step 4

In the Switch groups area of Group connections, click a box to configure the connections between the corresponding switch groups.

The connections between the switch groups are displayed in a matrix of boxes. The matrix defines how the switches are connected to one another. The top and side labels show the names of the switch groups; the labels match on both axes.

Each box shows the number of connections per switch group pair and is labelled with a letter such as A, B, or C. The Connections property specifies the number of connections, which you can change as indicated in the substeps. Each letter indicates a unique pair of switch PIDs, which can help you to identify outliers or misconfigurations quickly.

The switches of the switch group specified by the left label are connected under the switches of the switch group indicated by the top label. The exception is if the switch group is the same on both axes, in which case the switches of that group are interconnected.

As an example, assume you have two switches in a switch group named "Spine", four switches in another switch group named "Leaf", and you specify "2" for Connections between the groups. This means you have eight pairs of switches. Because you specified two connections, you have 16 total connections between the groups.

After you click a box, the right side of the Switch groups area shows the properties of the group connections. You can click multiple boxes to see each of those group connections at the same time.

For a selected switch group's connections, perform these substeps.

  1. Select the PID for the pluggables by clicking edit ( edit ).

    The Select PIDS for <switch_group> to <switch_group> dialog appears. Select the PID from the table at the bottom for the first switch group, select Cable and select a PID, then select the radio button for the second switch group and select a PID. You can filter the table using the fields above the table.

    Click Select after you are done.

  2. For Connections, enter the number of connections per switch pair.

    This is not the total number of connections between switch groups.

  3. For Cabling strategy, choose how you want to cable the switches.

  4. If you want to override the automatic cabling of the switches, in the Manual Overrides area, click Add override and select Connection override.

    The radio button on the left is selected by default. In the left tile, select the device and port from the drop-down lists, and select the pluggable from the table.

    Select Cable and select a PID.

    Select the radio button on the right. In the right tile, select the device and port from the drop-down lists, and select the pluggable from the table.

    Click Select.

Step 5

If your fabric will contain servers, follow these substeps.

  1. Click Add tier and select Server.

    By default, the server tier has one server group.

  2. If you want to change the default server tier name, click edit ( edit ) next to the default name, modify the name, and click Update.

  3. If you want to change the default group name and short name, click edit ( edit ) next to the default name, modify the name and short name, and click Update.

  4. From the drop-down list at the top of the group, select the server model.

  5. Enter a name for the hardware set and fill out the other fields.

    Cisco Nexus Hyperfabric uses the hardware set name as part of the device name.

    By default, the group has one hardware set. If you want to add another hardware set, click Add hardware set, then repeat this substep.

  6. If you want to add another server group, click Add group, then repeat substep 5.c and the subsequent substeps.

  7. If you want to add another server tier, repeat this entire step.

  8. If your fabric includes devices with GPUs, then in the Manage rail groups for East-West server port connections area, click Add rail group and fill out the fields for the group.

    • Rail group name: Enter a name.
    • Short name: Enter a short name.
    • Width: Enter the number of GPU servers.
    • Count: Enter 8. Currently, this is the only possible value.
    • Placement strategy: Select the strategy. Currently, you can only select Distributed for servers.
    • Switch group: Select the switch group to which this rail group will be connected.

  9. In the Server port groups to switch groups area, configure these things:

    • Pluggable PID <–: Click edit ( edit ) and select the pluggable for the group server. You can select the pluggable for Pluggable PID <– (group server), Cable PID, and Pluggable PID –> (switch group or rail group) in the same dialog.
    • Connections: This is the maximum number of possible connections. You cannot change this value. If you do not want any connections to the server port group, remove the value from Switch/rail group, if any.
    • Cabling strategy: Select a strategy.
    • Cable PID: Click edit ( edit ) and select the pluggable for the cable. You can select the pluggable for Pluggable PID <– (group server), Cable PID, and Pluggable PID –> (switch group or rail group) in the same dialog.
    • Pluggable PID –>: Click edit ( edit ) and select the pluggable for the switch group. You can select the pluggable for Pluggable PID <– (group server), Cable PID, and Pluggable PID –> (switch group or rail group) in the same dialog.
    • Switch/rail group: Select a switch group or rail group.

Step 6

Click Save fabric blueprint.

The Saving fabric blueprint dialog appears and informs you that Cisco Nexus Hyperfabric generated the blueprint.

Step 7

If you want Cisco Nexus Hyperfabric to create the cabling plan now, click Run cabling. Otherwise, click Continue to topology.

Create a fabric using a template

You can create a fabric using a template, which has a predefined topology. You select a template based on the size of the fabric that you want to create.

Follow these steps to create a fabric using a template.

Step 1

Choose Fabrics.

Step 2

Click + Add new fabric and select New from template.

Step 3

On the Templates page, select AI clusters or Switch fabrics as appropriate.

Step 4

Select the template with the topology that you want.

Step 5

If you want to change the default fabric name, click edit (edit) next to the name, enter a new name, and click Update.

Step 6

Modify the topology as appropriate, then click Save fabric blueprint.

Modifying fabrics

If you have administrator or read-write access to the organization, you can modify the design of an existing fabric on the Fabrics page. You can make changes to the fabric blueprint at any stage: from an undeployed fabric design to an installed and running fabric.

The Fabrics blueprint page operates in one of two modes:

  • Edit mode: This is the default mode for a user with administrator or read-write access. All fabric edit options are exposed.
  • Running mode: This is the default mode for a user with read-only access. Settings and status are displayed, but no edit options are exposed. You can switch to edit mode only if you have administrator or read-write access.

All configuration procedures in this document assume that you are logged in with administrator or read-write access, and that the menus are in edit mode.

Modify a fabric

This procedure provides the typical workflow for making fabric configuration changes.

Follow these steps to modify a fabric.

Step 1

Select Fabrics, then click the fabric that you want to configure.

Step 2

If the fabric is not in the edit mode, click Switch to edit mode.

Step 3

Make your changes.

Your changes are not applied to the fabric until you review, commit, and push them.

Step 4

When you're ready to apply your changes, click Review configuration.

Review configuration
Review configuration

In the Review configuration page, you can view a list of brief descriptions of the changes since the last push, including the author's ID and the date and time when the change was saved.

Step 5

When you have reviewed the changes and are ready to apply them, click Comment and push.

Step 6

In the Comment before pushing configuration dialog box, enter the reason for the change.

Step 7

Click Push configuration.

Step 8

View the status of your changes.

On the Fabrics blueprint page, view the fabric card to see the status of the pushed changes. Your changes may take some time to apply or they might generate red assertions. For example, if you push changes to an installed and running fabric, and the changes conflict with the physical cabling of the fabric, an assertion is raised.

Cabling

Cisco Nexus Hyperfabric automatically determines how you should cable the devices in a fabric based on the number of connections per device pair and cabling strategy. The cabling strategy comprises two notions.

The first notion comprises these things:

  • Strict: Cisco Nexus Hyperfabric connects each device pair with the number of connections that you selected. If a device does not have enough available ports for any reason, Cisco Nexus Hyperfabric indicates that there is an error with the cabling.
  • Best effort: Cisco Nexus Hyperfabric connects each device pair with the number of connections that you selected if possible. However, if a device does not have enough available ports for any reason, Cisco Nexus Hyperfabric connects the devices in the pair to other devices in the same switch group that have enough available ports.

The second notion comprises these things:

  • Dense: Cisco Nexus Hyperfabric connects consecutive ports of a device to consecutive ports of a paired device. The number of consecutive ports is equal to the number of connections per device pair that you selected. Cisco Nexus Hyperfabric repeats this connecting of consecutive ports for each successive paired device. This is used for switch-to-switch connections.
    Switch-to-switch dense cabling strategy with two spine switches and two leaf switches
    Switch-to-switch dense cabling strategy with two spine switches and two leaf switches
  • Distributed: Cisco Nexus Hyperfabric connects the first network interface card (NIC) of the first server to the first port of the first switch, then the second NIC of the server to the first port of the second switch, and so on until the server has one connection to the first port of each switch. Cisco Nexus Hyperfabric repeats this process with the successive servers, but the NICs connect to the successive port of each switch. After each servers' NICs are connected to each switch, the entire process repeats until there are a number of connections from each server to each switch equal to the specified number of connections. Server port groups that have GPUs also use the distributed cabling strategy. In the rail group properties, these servers have width equal to the number of GPU servers and a count of 8. With or without GPUs, the same NIC number on each server connects to the same switch. Thus, for a fabric with two servers (server1 and server2) and two switches (switch1 and switch2), NIC1 of both servers connect to switch1 while NIC2 of both servers connect to switch2.
    Switch-to-server distributed cabling strategy with two leaf switches and two servers
    Switch-to-server distributed cabling strategy with two leaf switches and two servers

If your fabric includes connections between devices in the same switch group or server group, Cisco Nexus Hyperfabric allocates ports to device pairs in different groups first, then allocates ports to devices in the same group.

Modify a fabric topology

To add or remove switches, or to otherwise modify the topology of an existing fabric, navigate to the Fabrics page. In this menu, you can define the blueprint for the fabric. See the terminology section in the Cisco Nexus Hyperfabric Getting Started document. When you modify the fabric, the Nexus Hyperfabric creates a new blueprint.

Follow these steps to modify a fabric topology.

Step 1

Select Fabrics, then click the fabric that you want to modify.

Step 2

If the fabric is not in the edit mode, click Switch to edit mode.

Step 3

In the Topology area, click Edit fabric.

Step 4

In the Edit fabric dialog box, set the properties as desired.

  1. Enter the fabric name.

  2. (Optional) Enter a description, address, and location of the fabric.

  3. Select the number of spine switches and leaf switches.

    For a single-switch fabric or a mesh fabric, select only leaf switches. If you select one or more spine switches, select two or more leaf switches to create a spine and leaf topology. As you make your switch selections, the topology diagram changes to display the resulting fabric.

Step 5

Click Save.

Considerations for modifying a fabric topology

Removing a switch or a cable from a fabric topology impacts traffic going through the interface that you removed from the fabric. Adding a switch or a cable does not impact traffic.

Finish and commit the design

Your changes are not applied to the fabric until you review, commit, and push them.

Follow these steps to finish and commit the design.

Step 1

Click Review configuration.

Step 2

Verify your changes in the review list.

Step 3

Click Comment and push.

Step 4

In the Comment before pushing configuration dialog box, enter the reason for the change.

Step 5

Click Push configuration.

If you bound any devices as part of this push, the outline color of the device icons indicates the assertions for the devices. The devices should have a green outline, which indicates that there are no issues. A yellow outline indicates the device has an unexpected condition and there are issues detected, but the issues should not cause operation disruption. A red outline indicates the device has an unexpected condition and there are issues detected that can cause operation disruption; you should investigate the issues.

Fabric topology after pushing a configuration
Fabric topology after pushing a configuration

Exporting and importing a fabric blueprint

Export a fabric blueprint

You can export a fabric blueprint, which Cisco Nexus Hyperfabric saves as a JSON file on your local system. One use case of exporting a blueprint is that you can then import that blueprint into another organization to create the same fabric in that organization.

Follow these steps to export a fabric blueprint.

Step 1

Choose Fabrics.

Step 2

For the fabric whose blueprint you want to export, select ... > Export running fabric.

Cisco Nexus Hyperfabric saves a JSON file of the blueprint on your local system.

Import a fabric blueprint

If you have a JSON file of a fabric blueprint, you can import that blueprint into your Cisco Nexus Hyperfabric organization to create a new fabric blueprint. Cisco Nexus Hyperfabric validates the blueprint when you attempt to import it. If Cisco Nexus Hyperfabric detects issues with the blueprint, it informs you of the issues and stops the import.

Follow these steps to import a fabric blueprint.

Step 1

Choose Fabrics.

Step 2

Click + Add new fabric and select Import fabric.

The Import fabric configuration dialog box appears.

  1. Drag and drop the JSON file from your local system to the Drag file here area of the dialog box.

    The Drop file to attach or Browse... text changes to display the name of the JSON file.

  2. For New fabric name, enter a name for the fabric.

    If you do not enter a name, the new fabric has the name of the fabric in the JSON file. However, if a fabric with that name already exists in your organization, you must enter a unique name.

    If you entered a name, the hostname of the devices in the fabric get prepended with that name of. This prevents devices in this organization from having the same hostname.

  3. Click Import.

    While the Cisco Nexus Hyperfabric imports the blueprint, Import changes to "Importing...". After Cisco Nexus Hyperfabric completes importing the blueprint, the fabric appears as part of your organization.

Clone a fabric blueprint

You can clone an existing fabric so that you have two identical fabric blueprints in the same organization.

Follow these steps to clone a fabric blueprint.

Step 1

Choose Fabrics.

Step 2

Click ... in the tile of the fabric that you want to clone and select Clone fabric.

The Clone fabric dialog box appears.

  1. For New fabric name, enter a name for the new fabric.

    The name cannot be the same as an existing fabric in this organization. The hostname of the devices in the fabric get prepended with the name of the fabric. This prevents devices in this organization from having the same hostname.

  2. Click Clone.

    While the Cisco Nexus Hyperfabric clones the fabric, Clone changes to "Cloning...". After Cisco Nexus Hyperfabric completes cloning the fabric, the fabric appears as part of your organization.

Considerations for exporting and importing a fabric blueprint

General considerations

The export and import functionality is not intended to be used as a save and restore functionality. For example, the JSON file of an exported fabric blueprint does not contain any password nor secrets.

Export considerations

These conderations apply for exporting a fabric blueprint:

  • An exported blueprint does not contain any uncommitted configuration changes. Thus, if you made changes to the fabric but did not commit the changes, Nexus Hyperfabric will not include those changes in the exported blueprint.
  • The JSON file of an exported fabric blueprint does not contain any passwords nor secrets.

Import considerations

These conderations apply for importing a fabric blueprint:

  • An imported fabric blueprint does not have any bound switches. You must bind switches after importing the JSON file.
  • After you import a fabric, you must manually configure any passwords and secrets that the fabric requires.
  • You cannot import a fabric into an organization that already has a fabric with the same name.

View Event viewer

Event viewer displays the time series for events such as failed assertions, resolved assertions, and configuration events for a device.

Step 1

Select Fabrics, then select Fabric > Event viewer.

Step 2

The Event Viewer area displays the time series for failed assertions, resolved or cleared assertions, and configuration events. The total count of new and resolved assertions are displayed for each time period. Configuration events are displayed separately as a line graph. From the drop-down list, select the time period. By default, Last hour is chosen.

Event viewer
Event viewer

Step 3

Use the Types drop-down list, to filter the event types.

 Note

Candidate comments displays comments you enter when you push a configuration and are only applicable for configuration events.

Step 4

In the Description column, click Configuration pushed to view additional details.

Configuration pushed
Configuration pushed