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Understanding LAN Fabrics, Release 12.2.1

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Last updated: April 8, 2024
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New and Changed Information

The following table provides an overview of the significant changes up to this current release. The table does not provide an exhaustive list of all changes or of the new features up to this release.

Release Version Feature Description

There were no major changes from the previous release.

LAN Fabrics

The following terms are referred to in this document:

  • Greenfield Deployments: Applicable for provisioning new VXLAN EVPN fabrics and eBGP-based routed fabrics.

  • Brownfield Deployments: Applicable for existing VXLAN EVPN fabrics:

    • Migrate CLI-configured VXLAN EVPN fabrics to Nexus Dashboard Fabric Controller using the Data Center VXLAN EVPN fabric template.

    • NFM migration to Cisco Nexus Dashboard Fabric Controller using the Data Center VXLAN EVPN fabric template.

Note that in this document the terms switch and device are used interchangeably.

For information about upgrades, refer to the Cisco Installation and Upgrade Guide for LAN Controller Deployment.

The following table describes the fields that appear on Manage > Fabrics.

Field Description

Fabric Name

Displays the name of the fabric.

Fabric Technology

Displays the fabric technology based on the fabric template.

Fabric Type

Displays the type of the fabric-Switch Fabric, LAN Monitor, or External

ASN

Displays the ASN for the fabric.

Fabric Health

Displays the health of the fabric.

The following table describes the action items in the Actions menu drop-down list, that appear on Manage > Fabrics.

Action Item Description

Create Fabric

From the Actions drop-down list, select Create Fabric. For more instructions, see Create a Fabric.

Edit Fabric

Select a fabric to edit. From the Actions drop-down list, select Edit Fabric. Make the necessary changes and click Save. Click Close to discard the changes.

Delete Fabric

Select a fabric to delete. From the drop-down list, select Delete Fabric. Click Confirm to delete the fabric.

Fabric Summary

Click on a fabric to open the side kick panel. The following sections display the summary of the fabric:

  • Health - Shows the health of the Fabric.

  • Alarms - Displays the alarms based on the categories.

  • Fabric Info - Provides basic about the Fabric.

  • Inventory - Provides information about Switch Configuration and Switch Health.

Click the Launch icon to the right top corner to view the Fabric Overview.

Understanding Fabric Templates

Fabric Templates

The following table provides information about the available fabric templates:

Type of Fabric

Description

REST API Template Name

Detailed Procedures

Data Center VXLAN EVPN

Fabric for a VXLAN EVPN deployment with Nexus 9000 and 3000 switches.

Easy_Fabric

Enhanced Classic LAN

Fabric for a fully automated 3-tier Classic LAN deployment with Nexus 9000 and 7000 switches.

Easy_Fabric_Classic

Campus VXLAN EVPN

Fabric for a VXLAN EVPN Campus deployment with Catalyst 9000 switches.

Easy_Fabric_IOS_XE

BGP Fabric

Fabric for an eBGP based deployment with Nexus 9000 and 3000 switches. Optionally VXLAN EVPN can be enabled on top of the eBGP underlay.

Easy_Fabric_eBGP

Custom Network

Fabric for flexible deployments with a mix of Nexus and Non-Nexus devices.

External_Fabric

Fabric Group

Domain that can contain Enhanced Classic LAN, Classic LAN, and External Connectivity Network fabrics.

Fabric_Group

Classic LAN

Fabric to manage a legacy Classic LAN deployment with Nexus switches.

LAN_Classic

LAN Monitor

Fabric for monitoring Nexus switches for basic discovery and inventory management.

LAN_Monitor

VXLAN EVPN Multi-Site

Domain that can contain multiple VXLAN EVPN Fabrics (with Layer-2/Layer-3 Overlay Extensions) and other Fabric Types.

MSD_Fabric

Classic IPFM

Fabric to manage or monitor existing Nexus 9000 switches in an IP Fabric for Media Deployment.

IPFM_Classic

IPFM

Fabric for a fully automated deployment of IP Fabric for Media Network with Nexus 9000 switches.

Easy_Fabric_IPFM

Multi-Site External Network

Fabric to interconnect VXLAN EVPN for Multi-Site deployments with a mix of Nexus and Non-Nexus devices.

External_Fabric

External Connectivity Network

Fabric for core and edge router deployments with a mix of Nexus and Non-Nexus devices.

External_Fabric

Prerequisites to Creating a Fabric

  • From Cisco NDFC Release 12.1.2e, the ESXi host default setting on the vSphere Client for promiscuous mode is supported. For more information, see ESXi Networking for Promiscuous Mode section. From Nexus Dashboard release 2.3.1c, the vNIC of the POD that has the Persistent IP shares the same MAC address of Nexus Dashboard bond0 or bond1 interface. Therefore, the POD sources the packets using the same MAC address of Nexus Dashboard bond0 or bond1 interfaces that are known by the VMware ESXi system.

  • Configure the persistent IP addresses in Cisco Nexus Dashboard. For more information, see Cluster Configuration section in Cisco Nexus Dashboard User Guide.

Create a Fabric

To create a Fabric using Cisco Nexus Dashboard Fabric Controller Web UI, perform the following steps:

  1. Choose Manage > Fabrics.

  2. From the Actions drop-down list, select Create Fabric.

  3. Enter the fabric name and click Choose Fabric.

  4. Specify the values for the fabric settings and click Save.

Locating Information on LAN Fabric Templates

The following table provides pointers to documents that give information and instructions specifically for each type of LAN fabric template.

Type of Fabric

Detailed Procedures

BGP Fabric

Campus VXLAN EVPN

Classic IPFM

Classic LAN

Custom Network

Data Center VXLAN EVPN

Enhanced Classic LAN

External Connectivity Network

Fabric Group

IPFM

LAN Monitor

Multi-Site External Network

VXLAN EVPN Multi-Site

Changing Persistent IP Address

You can change persistent IP addresses that are assigned for mandatory pods, such as POAP-SCP and SNMP traps.

note.svg

A known condition exists where you might have persistent IP addresses configured and assigned through NDFC, but then you disable the NDFC app through Nexus Dashboard, which puts those persistent IP addresses in an unassigned state. Even if you delete those persistent IP addresses, those deleted persistent IP addresses will reappear in an assigned state if you enable the NDFC app again at a later date through Nexus Dashboard.


To change the persistent IP address, perform the following steps:

  1. On the Cisco NDFC Web UI, navigate to Settings > Server Settings > Admin under LAN Device Management Connectivity drop-down list change Management to Data or conversely.

    Changing option results in migration of SNMP and POAP-SCP pods to the persistent IP addresses associated with External Service Pool on Nexus Dashboard connected with the new LAN Device Management Connectivity option. After the completion of this process, the following message is displayed:

    Some features have been updated. Reload the page to see latest changes.

    Click Reload the page.

  2. On Cisco Nexus Dashboard Web UI, navigate to Infrastructure > Cluster Configuration > General, in External Service Pools card, change the required IP addresses for Management Service IP Usage or Data Service IP Usage.

  3. Navigate to NDFC Web UI Server Settings page, change the option in LAN Device Management Connectivity drop-down list to its initial selection.

    Restoring this option to initial settings, results in migration of the SNMP and POAP-SCP pods to use the updated persistent IP address from the appropriate External Service IP pool.

Enabling ESXi Networking for Promiscuous Mode

From Cisco NDFC Release 12.1.2e, you can run NDFC on top of virtual Nexus Dashboard (vND) instance with promiscuous mode that is disabled on port groups that are associated with Nexus Dashboard interfaces where External Service IP addresses are specified. vND comprises Nexus Dashboard management interface and data interface. By default, for fabric controller persona, two external service IP addresses are required for the Nexus Dashboard management interface subnet.

Before the NDFC Release 12.1.2e, if Inband management or Endpoint Locator or POAP feature was enabled on NDFC, you must also enable promiscuous mode for the Nexus Dashboard data or fabric interface port-group. This setting was mandatory for traffic flow that is associated for these features.

Enabling promiscuous mode raise risk of security issues in NDFC, it is recommended to set default setting for promiscuous mode.

note.svg

  • Disabling promiscuous mode is supported from Cisco Nexus Dashboard Release 2.3.1c.

  • You can disable promiscuous mode when Nexus Dashboard nodes are layer-3 adjacent on the Data network, BGP is configured, and fabric switches are reachable through the data interface.

  • You can disable promiscuous mode when Nexus Dashboard interfaces are layer-2 adjacent to switch mgmt0 interface.


If Inband management or EPL is enabled, you must specify External Service IP addresses in the Nexus Dashboard data interface subnet. You can disable promiscuous mode for the Nexus Dashboard data or fabric interface port-group. For more information, refer to the Cisco Nexus Dashboard Deployment Guide.

note.svg

Default option for promiscuous mode is Reject.


  1. Log into your vSphere Client.

  2. Navigate to the ESXi host.

  3. Right-click the host and choose Settings.

    A sub-menu appears.

  4. Choose Networking > Virtual Switches.

    All the virtual switches appear as blocks.

  5. Click Edit Settings of the VM Network.

  6. Navigate to the Security tab.

  7. Update the Promiscuous mode settings as follows:

    • Check the Override check box.

    • Choose Accept from the drop-down list.

  8. Click OK.

Overlay Mode

You can create a VRF or network in CLI or config-profile mode at the fabric level. The overlay mode of member fabrics of an MSD fabric is set individually at the member-fabric level. Overlay mode can only be changed before deploying overlay configurations to the switches. After the overlay configuration is deployed, you cannot change the mode unless all the VRF and network attachments are removed.

note.svg

If you upgrade from Cisco DCNM Release 11.5(x), the existing config-profile mode functions the same.


If the switch has config-profile based overlays, you can import it in the config-profile overlay mode only. If you import it in the cli overlay mode, an error appears during brownfield import.

For brownfield import, if overlay is deployed as config-profile mode, it can be imported in config-profile mode only. However, if overlay is deployed as cli, it can be imported in either config-profile or cli modes.

To choose the overlay mode of VRFs or networks in a fabric, perform the following steps:

  1. Navigate to the Edit Fabric window.

  2. Go to the Advanced tab.

  3. From the Overlay Mode drop-down list, choose config-profile or cli.

    The default mode is config-profile.

Netflow Support

Configuring Netflow at the fabric level allows you to collect, record, export, and monitor network flow and data to determine network traffic flow and volume for further analysis and troubleshooting. From Cisco NDFC Release 12.0.2, you can configure Netflow for Easy Fabrics, Easy Fabric eBGP, External Fabric, and LAN Classic templates.

After netflow is enabled for fabric, you can configure netflow on a network, or an interface (VLAN, SVI, physical interface, sub-interface, or port-channel). Before enabling netflow on the interface or network, ensure that the specified monitor name is defined in the fabric settings.

When Netflow is enabled at the Fabric level, the configuration is generated for netflow capable switches (FX/GX/EX) in the fabric except for spine/super-spine or switches with no_netflow policy. In a Multi-Site domain configuration, netflow is configured per Easy Fabric and not for the entire Multi-Site domain.

note.svg

NDFC does not validate the Netflow Monitor name.


The following are the guidelines for Netflow configuration on other networks elements:

  • For VRF Lite IFC, the netflow configuration is not inside the configuration profile, regardless of overlay mode.

  • For networks, netflow configurations are not inside the configuration profile, regardless of overlay mode.

  • You can configure netflow for Layer 2 Interface on trunk ports, access ports, dot1q tunnels, Layer2 port-channel, and VPC ports.

  • You can configure netflow for the Layer 3 interface on SVI, Routed host, L3 Port-Channel, and sub-interfaces.

  • Netflow configuration for VLANs uses vlan_netflow Record Template. In Brownfield deployment, the netflow configuration for VLANs is in switch freeform.

  • You can enable Netflow under SVI (for routed traffic) or Vlan Configuration (for switched traffic).

  • To configure IPv6 flow monitoring, use switch_freeform or interface freeform.

  • Netflow configuration under the trunk or routed port is in interface freeform.

  • For Host port resync, netflow configuration is captured in interface freeform.

  • There is no explicit support for netflow in Intra-Fabric link or Multisite Underlay IFC. Note that you can use freeform configuration.

Netflow Support for Brownfield deployments

For Brownfield deployments, global netflow configuration for export, record, and monitor are not captured due to the telemetry use case. After brownfield import, to avoid global level netflow command being removed, you can perform the following actions:

  • Do not turn on strict CC.

  • Include the netflow global configuration in switch freeform.

  • Enable Netflow in the fabric setting matching with the switch configuration.

    Interface and VLAN level netflow configuration on the switch will be captured in freeform.

  • SVI netflow config is captured in switch_freeform tied to the network.

  • Netflow configuration for trunk or routed ports is in the interface freeform.

  • Netflow configuration for VLANs is in the switch_freeform.

  • The sub-interface configuration for VRF-Lite extensions is in int_freeform.

VXLAN OAM

In Nexus Dashboard Fabric Controller, VXLAN OAM is supported on VXLAN Fabric, eBGP VXLAN Fabric, External, and Lan Classic fabric technologies. You can track details such as reachability and actual path of the flows in a VXLAN EVPN based-fabric topology.

Guidelines

  • OAM must be enabled on the switches before using the OAM trace.

    note.svg

    VXLAN OAM IPv6 is supported from Irvine release onwards.


  • NX-API and NX-API on HTTP port must be enabled.

  • vPC advertise-pip must be enabled.

  • For switch-to-switch OAM, ensure that the VRFs are configured along with loopback interfaces with IPv4 and/or IPv6 addresses under those VRFs.

  • For host-to-host OAM, ensure that the Networks are configured along with IPv4 and/or IPv6 gateway configuration.

  • From Cisco NDFC Release 12.1.1e, IPv6 underlay is supported with VXLAN OAM. To enable the VXLAN OAM support over IPv6 underlay, perform any one of the following steps:

    • On the Topology window:

      • Choose Actions > Add Fabric.

      • On the General Parameters tab, check the Enable IPv6 Underlay check box.

    • On the LAN Fabrics window:

      • Choose Actions > Create Fabric.

      • On the General Parameters tab, check the Enable IPv6 Underlay check box.

      note.svg

      Changing of IPv4 to IPv6 underlay is not supported for existing fabric settings.


    To change the fabric settings from IPv4 to IPv6 underlay, delete the existing fabric and create new fabric with Underlay IPV6 enabled.

UI Navigation

  • In the Topology window: Click Actions. Choose VXLAN OAM option from the drop-down list.

  • From LAN Fabrics window: Choose Manage > Fabrics. Navigate to the fabric overview window of a fabric. Click Actions. Choose VXLAN OAM option from the drop-down list.

The VXLAN OAM window appears. The Path Trace Settings pane on the left displays the Switch to Switch and Host to Host tabs. Nexus Dashboard Fabric Controller highlights the route on the topology between the source and destination switch for these two options.

The Switch to Switch option provides the VXLAN OAM ping and traceroute test results for the VTEP-to-VTEP use-case. Provide the following values to enable search by using the Switch to Switch option:

  • In the Source Switch drop-down list, choose the source switch.

  • In the Destination Switch drop-down list, choose the destination switch.

  • From the VRF drop-down list, choose or enter the VRF details.

  • Check the All paths included check box to include all the paths in the search results.

The Host to Host option provides the VXLAN OAM path trace results for the exact path that is taken by a given flow from the VTEP or switch that is connected to the source host to VTEP or switch that is connected to the destination host. For the Host to Host use-case, there are two options:

  • VRF or SVI for a network is instantiated on the switches in the VXLAN EVPN fabric. In such a scenario, the IP address information of the end hosts is required.

  • Layer 2 configuration for a given network is instantiated on the switches in the VXLAN EVPN fabric. In such a scenario, both the MAC and IP address information of the end hosts are required.

Provide the following values to enable search using the Host to Host option:

  • From the Source Host IP field, enter the IPv4/IPv6 address of the source host.

  • From the Destination Host IP field, enter the IPv4/IPv6 address of the destination host.

  • In the VRF field, choose VRF from the drop-down list or enter the VRF name that is associated with the hosts.

  • In the Source Port field, choose Layer 4 source port number from the drop-down list or enter its value.

  • In the Destination Port field, choose destination port number or enter its value.

  • In the Protocol field, choose the protocol value from the drop-down list or enter its value. This is the Layer 4 protocol, usually TCP or UDP.

  • Check the Layer 2 only check box to search the VXLAN-EVPN fabric that is deployed in Layer 2 only mode for some networks, that is, Layer 2 VNIs. No SVIs or VRFs should be instantiated in the fabric for these networks when you use this search option. When you check this option, you have to enter details of the source MAC address, destination MAC address, and VNI too.

Click Run Path Trace to view the path trace from switch to switch or host to host.

You can view the forward path and reverse path as well in the topology. The summary of the path trace appears in the Summary tab. You can view the details of the forward and reverse paths as well under Forward Path or Reverse Path tabs. Filter the results by attributes, if needed.

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