White Papers

Name Server
Each participant in the FC environment has a unique ID, which is called the World Wide Name (WWN). This WWN is a 64-bit
address.
A Fibre Channel fabric uses another addressing scheme to address the ports in the switched fabric. Each port in the switched
fabric is assigned a 24-bit address by the FC switch. When the device logs into the switch fabric on a specific port with its
WWN, the switch assigns the port address to that port, and the switch also maintains the correlation between the port address
and the WWN address of the device on that port. This function of the switch is implemented by using a name server, a database
of objects in which the fabric attached device registers its values.
FC-ID: 24-bit port address. Consists of three parts:
● Domain: Address of the switch itself. There are only 239 addresses available for switches in your SAN environment.
● Area: Identifies a group of F_Ports. Each group of ports has a different area number, even if there is only one port in the
group.
● Port: Provides 256 addresses for identifying attached N_Ports and NL_Ports.
The following sequence explains the operation for the attached N_Port:
● N_Port sends a Fabric Login (FLOGI) as it requests a unique 24-bit address from the Fabric Login Server.
● N_Port sends FLOGI to address 0xFFFFFE. Upon success, it obtains a valid address (FCID).
● N_Port sends a Port Login (PLOGI) to inform the Fabric Name Server of its personality and capabilities, this includes
WWNN, WWPN.
● N_Port sends PLOGI to address 0xFFFFFC to register this address with the name server.
Command
Description
show fc ns
switch
Display all the devices in name server database of the switch.
show fc ns
switch brief
Displays the local name server entries — brief version.
The following configurations are applicable only after configuring the switch mode to FCF Port mode using the feature fc
fport domain id 2 command. When you set Switch mode to FCF Port mode, any previously configured fcoe-map is
removed.
FCoE Maps
To identify the SAN fabric to which FCoE storage traffic is sent, use an FCoE map.
Using an FCoE map, an NPG operates as an FCoE-FC bridge between an FC SAN and FCoE network by providing FCoE-enabled
servers and switches with the necessary parameters to log in to a SAN fabric.
An FCoE map applies the following parameters on server-facing Ethernet and fabric-facing FC ports:
● The dedicated FCoE VLAN used to transport FCoE storage traffic.
● The FC-MAP value used to generate a fabric-provided MAC address.
●
The association between the FCoE VLAN ID and FC fabric ID where the desired storage arrays are installed. Each Fibre
Channel fabric serves as an isolated SAN topology within the same physical network.
● A server uses the priority to select an upstream FCoE forwarder (FCF priority).
● FIP keepalive (FKA) advertisement timeout.
NOTE:
In each FCoE map, the fabric ID, FC-MAP value, and FCoE VLAN must be unique. To access one SAN fabric, use
one FCoE map.
When you configure a switch as an NPG, FCoE transit with FIP snooping is automatically enabled and configured using the
parameters in the FCoE map applied to server-facing Ethernet and fabric-facing FC interfaces.
After you apply an FCoE map on an FC port, when you enable the port (using the no shutdown command), the NPG starts
sending FIP multicast advertisements on behalf of the FC port to downstream servers to advertise the availability of a new FCF
port on the FCoE VLAN. The FIP advertisement also contains a keepalive message to maintain connectivity between a SAN
fabric and downstream servers.
FC FPORT
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