Cisco APIC Layer 2 Networking Configuration Guide, Release 6.2(x)

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Cisco APIC Layer 2 Networking Configuration Guide, Release 6.2(x)

Managing Fibre Channel NPV traffic

Updated: July 7, 2026

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Provides guidance on managing FC NPV traffic when automatic traffic engineering does not meet specific network requirements. It helps administrators determine when to override default uplink traffic distribution.

FC NPV traffic management is a configuration method used to control how traffic is distributed across available uplinks.

  • Overrides automatic traffic engineering.

  • Optimizes uplink utilization based on specific network requirements.

Note

We recommend that you allow all traffic to use all available uplinks.

Use FC NPV traffic management only when automatic traffic engineering does not meet your network requirements.

Automatic Uplink Selection is a feature that enables NPV to choose an external interface with the minimum load when a server interface becomes operational.

  • Selection occurs from available external interfaces within the same VSAN as the server interface.

  • Load balancing is determined by the current traffic load on the available uplinks.

Operational behavior of uplink selection

The system manages uplink selection based on the operational state of interfaces:

  • Initial Selection: When a server interface is brought up, the system selects the external interface with the minimum load.

  • New Uplink Availability: When a new external interface becomes operational, existing traffic is not automatically redistributed to the new link.

  • Post-Availability Selection: Server interfaces that transition to an operational state after the new external interface is available can select that new uplink.

Traffic maps

A traffic map is a configuration that allows you to specify the external (NP uplink) interfaces that a server (host) interface can use to connect to core switches.

  • Enables traffic engineering by pinning server interfaces to a fixed set of external interfaces.

  • Supports persistent FC ID operations by maintaining consistent traffic paths after reinitialization or reboot.

Traffic map operational requirements

When an FC NPV traffic map is configured for a server interface, the following operational constraints apply:

  • The server interface must select only from the external interfaces defined in its traffic map.

  • If none of the specified external interfaces are operational, the server interface remains in a non-operational state.

Note

When an FC NPV traffic map is configured for a server interface, the server interface must select only from the external interfaces in its traffic map. If none of the specified external interfaces are operational, the server remains in a non-operational state.

Disruptive auto load balancing

Disruptive auto load balancing is a feature that redistributes server interfaces across all available NP uplinks when a new NP uplink becomes operational.

When you enable this feature, the system forces a reinitialization of the server interface. This process forces the server to perform a new login to the core switch. Note the following operational behaviors:

  • Forces reinitialization of server interfaces to facilitate new logins to the core switch.

  • Redistributes traffic only for server interfaces moved to a different uplink.

  • Generates a system message for each moved server interface.

Operational considerations for disruptive load balancing

To maintain network stability, consider the following operational guidelines:

  • Enable this feature only after adding a new NP uplink.

  • Disable the feature immediately after server interfaces have been redistributed to prevent unnecessary traffic disruption.

  • Perform manual reinitialization of server interfaces if disruptive load balancing is not enabled.

Note

Redistributing a server interface causes traffic disruption to the attached end devices. Adding a member to the existing port-channel does not trigger disruptive auto load-balance.

FC NPV traffic management guidelines

FC NPV traffic management is a configuration feature that allows administrators to manually control the mapping of server interfaces to specific NP uplink interfaces.

  • Provides manual control over traffic engineering when automatic methods are insufficient.

  • Enables pinning of server interfaces to specific core switches via NP uplinks.

  • Supports persistent FC ID configurations for consistent traffic routing.

Traffic management operational guidelines

Follow these guidelines when deploying FC NPV traffic management:

  • Use FC NPV traffic management only when automatic traffic engineering does not meet your network requirements.

  • You do not need to configure traffic maps for all server interfaces. By default, FC NPV will use automatic traffic management.

  • Server interfaces configured to use a set of NP uplink interfaces cannot use any other available NP uplink interfaces, even if none of the configured interfaces are available.

  • When disruptive load balancing is enabled, a server interface may be moved from one NP uplink to another NP uplink. Moving between NP uplink interfaces requires FC NPV to relogin to the core switch, causing traffic disruption.

  • To link a set of servers to a specific core switch, associate the server interfaces with a set of NP uplink interfaces that all connect to that core switch.

  • Configure Persistent FC IDs on the core switch and use the traffic map feature to direct server interface traffic onto NP uplinks that all connect to the associated core switch.

  • When initially configuring traffic map pinning, you must shut the server host port before configuring the first traffic map.

  • If traffic mapping is configured for more than one uplink, when removing the traffic map through which a host has logged in, you must first shut the host before removing the traffic map.

  • While configuring a traffic map for an FCoE host behind a FEX, you can map one host to either multiple FCoE NP/uplinks (VFC or VFC-PO) or to a single Fibre Channel/SAN port channel NP/uplink.

Note

When a server is statically mapped to an external interface, the server traffic is not redistributed in the event that the external interface becomes down for any reason.