H3C Technologies H3C S12500-X Series Switches - Manual (Page 104)

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Configuring NPV
Overview
NPV enables an FC SAN to accommodate more than 239 switches.
NPV switches forward traffic from nodes to the core switch.
Figure 29 shows a typical NPV network diagram.
Figure 29 NPV network diagram
NOTE:
An NPV switch must be directly connected to the core switch.
Downlink interface and downlink
A downlink interface, also known as a server interface, is an interface through which an NPV switch
connects to a node. It can only be a VFC interface operating in F mode.
A downlink is a link from an NPV switch to its node.
Each downlink interface is uniquely mapped to an operational uplink interface, through which all traffic
from the nodes connected to the downlink interface is forwarded to the core switch.
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 only be a VFC interface operating in NP mode.
An uplink is a link from an NPV switch to the core switch.
After the uplink is operational, the NPV switch sends a fabric login (FLOGI) packet to the core switch for
registration, which assigns the uplink interface (NP_Port) an FC address. Then, the NPV switch registers
itself with the name server on the core switch. The NPV switch forwards traffic (including FLOGI packets)
from a node to the core switch through the mapped uplink interface and passes response packets from
the core switch to nodes through the downlink interface.