Cisco Nexus 5000 Series Switch CLI Software Configuration Guide, NX-OS 4.0(1a)N1 (OL-16597-01, January 2009)

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29-2
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
OL-16597-01
Chapter 29 Configuring FCoE
Information About FCoE
Converged Network Adapters
The following types of converged network adapters (CNAs) are available:
• Hardware adapter
– Works with the existing FC HBA driver and LAN NIC driver in the server.
– Server operating system view of the network is unchanged; the CNA presents a SAN interface
and a LAN interface to the operating system.
• FCoE software stack
– Runs on existing 10-Gigabit Ethernet adapters.
FCoE offers a number of optional capabilities. The available capabilities and their configurable values
are negotiated between the switch and the adapter. To accomplish this, the adapter and the switch
exchange information using the Data Center Bridging Exchange Protocol (DCBX).
To reduce configuration errors and simplify administration. you can configure the switch to distribute
the configuration data to all the connected adapters.
DCBX Capabilities
The DCBX capabilities supported by Cisco Nexus 5000 Series switches are described in the following
topics:
• FCoE, page 29-2
• Priority Flow Control, page 29-2
• Logical Link Up/Down, page 29-3
FCoE
By default, each Ethernet interface attempts to enable FCoE capability by advertising the capability to
the adapter.
If the FCoE negotiation fails, you can configure the switch to disable FCoE or to force-enable FCoE for
this interface.
Priority Flow Control
The priority flow control (PFC) capability allows you to apply pause functionality to specific classes of
traffic. PFC decides whether to apply pause based on the IEEE 802.1p CoS value. When the switch
enables PFC, it configures the connected adapter to apply the pause functionality to packets with specific
CoS values.
By default, the switch negotiates to enable the PFC capability. If the negotiation succeeds, PFC is
enabled and link-level flow control remains disabled (regardless of its configuration settings).
If the PFC negotiation fails, you can either force PFC to be enabled on the interface or you can enable
IEEE 802.x link-level flow control.
Link-level flow control can be enabled on the interface only if PFC is not enabled. For additional
information about link-level flow control, see the “Link-Level Flow Control” section on page 31-3.