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Uplink interface and uplink
An uplink interface, also known as an external interface, is the interface through which an NPV switch
connects to the core switch. It can be an FC interface, FC aggregate interface, or VFC interface, both of
which must be configured to operate in NP mode.
An uplink is a link from an NPV switch to the core switch.
When the uplink becomes operational, the NPV switch sends a fabric login (FLOGI) packet to the core
switch for registration. The core switch assigns the uplink interface (NP_Port) an FC address. Then, the
NPV switch registers itself with the name server on the core switch. When receiving a packet from a node,
the NPV switch performs the following operations:
• Forwards the packet to the core switch through the mapped uplink interface.
• Passes the response packet from the core switch to the node through the downlink interface.
Downlink-to-uplink interface mappings
NPV switches automatically map downlink interfaces to uplink interfaces. Before a downlink interface is
brought up, the NPV switch maps it to the uplink interface to which the minimum number of downlink
interfaces is mapped.
Typically, automatic mapping can meet your requirements. When a downlink interface must be
connected to a fabric through the specified uplink interfaces, you can manually map the uplink interfaces.
After you configure the mapping, the downlink interface can be mapped to only the configured uplink
interfaces. If none of the configured uplink interfaces is operational, the downlink interface cannot be
operational.
A configured mapping selects the uplink interface with the minimum load from configured uplink
interfaces and then maps the downlink interface to it.
After a mapping is established, all traffic from the downlink interface is forwarded through the uplink
interface.
Disruptive load balancing
When a new uplink interface becomes operational, the NPV switch does not perform a remapping for
load balancing. In the event of remapping, the NPV switch reinitializes the downlink interface. Then, the
node connected to the downlink interface registers with the core switch again. This causes traffic
interruption to the node.
You can trigger a remapping by using commands for better load balancing. In this case, the NPV switch
reinitializes all downlink interfaces.
NPV configuration task list
Tasks at a
lance
Remarks
(Required.) FC and FCoE configuration guidelines
Configuring the switch to operate in NPV mode.
(Required.) Configuring uplink interfaces and downlink
interfaces
N/A
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