Your software release might not support all the features documented in this module. For the latest caveats and feature information, see the Bug Search Tool at https://tools.cisco.com/bugsearch/ and the release notes for your software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the New and Changed chapter or the Feature History table below.

N port virtualization (NPV) reduces the number of Fibre Channel domain IDs in SANs. Switches operating in the NPV mode do not join a fabric. They pass traffic between NPV core switch links and end devices, which eliminates the domain IDs for these edge switches.

NPV is supported by the following Cisco MDS 9000 switches only:

• Cisco MDS 9148S 16G Multilayer Fabric Switch

• Cisco MDS 9250i Multiservice Fabric Switch

• Cisco MDS 9396S 16G Multilayer Fabric Switch

Note	NPV is available on these switches only while in NPV mode; if in switch mode, NPV is not available.

N port identifier virtualization (NPIV) provides a means to assign multiple FC IDs to a single N port. This feature allows multiple applications on the N port to use different identifiers and allows access control, zoning, and port security to be implemented at the application level Figure 1 shows an example application using NPIV.

You must globally enable NPIV for all VSANs on the MDS switch to allow the NPIV-enabled applications to use multiple N port identifiers.

Note	All of the N port identifiers are allocated in the same VSAN.

Typically, Fibre Channel networks are deployed using a core-edge model with a large number of fabric switches connected to edge devices. Such a model is cost-effective because the per port cost for director class switches is much higher than that of fabric switches. However, as the number of ports in the fabric increases, the number of switches deployed also increases, and you can end up with a significant increase in the number of domain IDs. This challenge becomes even more difficult when additional blade chassis are deployed in Fibre Channel networks.

NPV addresses the increase in the number of domain IDs needed to deploy a large number of the ports by making a fabric or blade switch appear as a host to the core Fibre Channel switch, and as a Fibre Channel switch to the servers in the fabric or blade switch. NPV aggregates multiple locally connected N ports into one or more external NP links, which shares the domain ID of the NPV core switch among multiple NPV switches. NPV also allows multiple devices to attach to same port on the NPV core switch, which reduces the need for more ports on the core

For more information on scalability limits, see the Cisco MDS NX-OS Configuration Limits guide.

While NPV is similar to N port identifier virtualization (NPIV), it does not offer exactly the same functionality. NPIV provides a means to assign multiple FC IDs to a single N port, and allows multiple applications on the N port to use different identifiers. NPIV also allows access control, zoning, and port security to be implemented at the application level. NPV makes use of NPIV to get multiple FCIDs allocated from the core switch on the NP port.

Note	For the Cisco MDS 9124, Cisco MDS 9134, and Cisco MDS 9148 legacy switches and the Cisco MDS 9148S and Cisco MDS 9396S switches supporting NPV mode, the nested NPV switches are not supported in the topology.

Figure 2 shows a more granular view of an NPV configuration at the interface level.

A switch is in NPV mode after a user has enabled NPV and the switch has successfully rebooted. NPV mode applies to an entire switch. All end devices connected to a switch that is in NPV mode must log in as an N port to use this feature (loop-attached devices are not supported). All links from the edge switches (in NPV mode) to the NPV core switches are established as NP ports (not E ports), which are used for typical interswitch links. NPIV is used by the switches in NPV mode to log in to multiple end devices that share a link to the NPV core switch.

Note	In-order data delivery is not required in NPV mode because the exchange between two end devices always takes the same uplink to the core from the NPV device. For traffic beyond the NPV device, core switches will enforce in-order delivery if needed and/or configured.

After entering NPV mode, only the following commands are available:

An NP port (proxy N port) is a port on a device that is in NPV mode and connected to the NPV core switch using an F port. NP ports behave like N ports except that in addition to providing N port behavior, they also function as proxies for multiple, physical N ports.

An NP link is basically an NPIV uplink to a specific end device. NP links are established when the uplink to the NPV core switch comes up; the links are terminated when the uplink goes down. Once the uplink is established, the NPV switch performs an internal FLOGI to the NPV core switch, and then (if the FLOGI is successful) registers itself with the NPV core switch’s name server. Subsequent FLOGIs from end devices in this NP link are converted to FDISCs. For more details refer to the Internal FLOGI Parameters section.

Server links are uniformly distributed across the NP links. All the end devices behind a server link will be mapped to only one NP link.

Port numbers on NPV-enabled switches will vary depending on the switch model. For details about port numbers for NPV-eligible switches, see the Cisco NX-OS Series Licensing Guide.

NPV devices use only IP as the transport medium. CFS uses multicast forwarding for CFS distribution. NPV devices do not have ISL connectivity and FC domain. To use CFS over IP, multicast forwarding has to be enabled on the Ethernet IP switches all along the network that physically connects the NPV switch. You can also manually configure the static IP peers for CFS distribution over IP on NPV-enabled switches. For more information, see the Cisco MDS 9000 Series NX-OS System Management Configuration Guide.

Before Cisco MDS SAN-OS Release 3.3(1a), NPV supported automatic selection of external links. When a server interface is brought up, an external interface with the minimum load is selected from the available links. There is no manual selection on the server interfaces using the external links. Also, when a new external interface was brought up, the existing load was not distributed automatically to the newly available external interface. This newly brought up interface is used only by the server interfaces that come up after this interface.

As in Cisco MDS SAN-OS Release 3.3(1a) and NX-OS Release 4.1(1a), NPV supports traffic management by allowing you to select and configure the external interfaces that the server uses to connect to the core switches.

Note	When the NPV traffic management is configured, the server uses only the configured external interfaces. Any other available external interface will not be used.

The NPV traffic management feature provides the following benefits:

• Facilitates traffic engineering by providing dedicated external interfaces for the servers connected to NPV.
• Uses the shortest path by selecting external interfaces per server interface.
• Uses the persistent FC ID feature by providing the same traffic path after a link break, or reboot of the NPV or core switch.
• Balances the load by allowing the user to evenly distribute the load across external interfaces.

Disruptive load balance works independent of automatic selection of interfaces and a configured traffic map of external interfaces. This feature forces reinitialization of the server interfaces to achieve load balance when this feature is enabled and whenever a new external interface comes up. To avoid flapping the server interfaces too often, enable this feature once and then disable it whenever the needed load balance is achieved.

If disruptive load balance is not enabled, you need to manually flap the server interface to move some of the load to a new external interface.

By grouping devices into different NPV sessions based on VSANs, it is possible to support multiple VSANs on the NPV-enabled switch. The correct uplink must be selected based on the VSAN that the uplink is carrying.

Following are recommended guidelines and requirements when deploying NPV:

• NPV core switches must support NPIV.

• You can have up to 105 NPV devices.

• Nondisruptive upgrades are supported. See the Cisco MDS 9000 Series NX-OS Fundamentals Configuration Guide.

• Port tracking is supported. See the Cisco MDS 9000 Series NX-OS Security Configuration Guide.

• You can configure zoning for end devices that are connected to edge switches using all available member types on a core switch. However, the preferred way of zoning servers connected to any switch in NPV mode is via pWWN, device-alias, and fc alias. Multiple servers should be configured in the same zone only when using smart zoning. The smart zoning feature is available on all MDS switches. For more information, see the Smart Zoning section in the Configuring and Managing Zones chapter of the Cisco MDS 9000 Series Fabric Configuration Guide.

• Port security is supported on the NPV core switch for devices logged in via NPV.

• NPV uses a load-balancing algorithm to automatically assign end devices in a VSAN to one of the NPV core switch links (in the same VSAN) upon initial login. If there are multiple NPV core switch links in the same VSAN, then you cannot assign a specific one to an end device.

• Both servers and targets can be connected to an NPV device.

• Remote SPAN is not supported.

• Local switching is not supported; all traffic is switched using the NPV core switch.

• NPV devices can connect to multiple NPV core switches. In other words, different NP ports can be connected to different NPV core switches.

• NPV supports NPIV-capable servers. This capability is called nested NPIV.

• Connecting two Cisco NPV switches together is not supported.

• Only F, NP, and SD ports are supported in NPV mode.

• In the case of servers that are booted over the SAN with NPV, if an NPV link failover occurs, servers will lose access to their boot LUN temporarily.

• NPV switches do not recognize the BB_SCN configuration on the xNP ports because of interoperability issues with the third-party core switches.

When deploying NPV traffic management, follow these guidelines:

• Use NPV traffic management only when the automatic traffic engineering by the NPV device is not sufficient for the network requirements.
• Do not configure traffic maps for all the servers. For non-configured servers, NPV will use automatic traffic engineering.
• Configure the Persistent FC ID on the core switch. Traffic engineering directs the associated server interface to external interfaces that lead to the same core switch. The server will be assigned the same FC ID for every log in. This guideline is not applicable if a 91x4 switch is used as the core switch.
• Server interfaces configured to a set of external interfaces cannot use any other available external interfaces, even if the configured interfaces are not available.
• Do not configure disruptive load balancing because this involves moving a device from one external interface to another interface. Moving the device between external interfaces requires NPV relogin to the core switch through F port leading to traffic disruption.
• Link a set of servers to a core switch by configuring the server to a set of external interfaces that are linked to the core switch.

When NPV is enabled, the following requirements must be met before you configure DPVM on the NPV core switch:

• You must explicitly configure the WWN of the internal FLOGI in DPVM. If DPVM is configured on the NPV core switch for an end device that is connected to the NPV device, then that end device must be configured to be in the same VSAN. Logins from a device connected to an NPV device will fail if the device is configured to be in a different VSAN. To avoid VSAN mismatches, ensure that the internal FLOGI VSAN matches the port VSAN of the NP port.

• The first login from an NP port determines the VSAN of that port. If DPVM is configured for this first login, which is the internal login of the NPV device, then the NPV core switch’s VSAN F port is located in that VSAN. Otherwise, the port VSAN remains unchanged.

For details about DPVM configuration, see the Cisco MDS 9000 Series NX-OS Fabric Configuration Guide.

Port security is enabled on the NPV core switch on a per interface basis. To enable port security on the NPV core switch for devices logging in via NPV, you must adhere to the following requirements:

• The internal FLOGI must be in the port security database so that, the port on the NPV core switch will allow communications and links.

• All of the end device pWWNs must also be in the port security database.

Once these requirements are met, you can enable port security as you would in any other context. For details about enabling port security, see the Cisco MDS 9000 Series NX-OS Security Configuration Guide.

This topic provides information about connecting an NPIV-enabled Cisco MDS 9396S Multilayer Fabric Switch to an NPV switch running Cisco MDS NX-OS Release 6.2(13) and earlier.

When trunking is enabled on the NPV ports of any MDS switch (released before the Cisco MDS 9396S Multilayer Fabric Switch) that runs on an Cisco MDS NX-OS Release 6.2(13) and earlier, and you connect an NPIV enabled Cisco MDS 9396S Multilayer Fabric Switch, use ports fc1/1 through fc1/63.

Note	Trunking failure can occur in both non-portChannel (individual physical NP uplinks) and portChannel NP uplinks. To avoid trunking failure, ensure that you upgrade the NPV switch to Cisco MDS NX-OS Release 6.2(13) or later.

The NPV traffic management feature is enabled after configuring NPV. Configuring NPV traffic management involves configuring a list of external interfaces to the servers, and enabling or disabling disruptive load balancing.

To display NPV configuration information, perform one of the following tasks:

For detailed information about the fields in the output from these commands, refer to the Cisco MDS 9000 Series NX-OS Command Reference.