Overview; Information About Fibre Channel Over Ethernet; Fibre Channel Forwarder; Chapter - Cisco Nexus 7000 series Configuration Manual

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Table of Contents

Overview

This chapter includes the following sections:

•

Fibre Channel over Ethernet (FCoE) allows Fibre Channel traffic to be encapsulated over a physical Ethernet

link. FCoE and FIP frames use a unique EtherType so that FCoE traffic and standard Ethernet traffic can be

carried on the same link.

Classic Ethernet is a best-effort protocol, which means that in a congested network, Ethernet discards packets

and relies on higher level protocols to provide retransmission and other reliability mechanisms.

Fibre Channel traffic requires a lossless transport layer; as a data storage protocol, it is unacceptable to lose

a single data packet. Native Fibre Channel implements a lossless service at the transport layer using a

buffer-to-buffer credit system.

Ethernet links on Cisco NX-OS switches provide two mechanisms to ensure lossless transport for FCoE traffic:

link-level flow control and priority flow control.

IEEE 802.3x link-level flow control allows a congested receiver to signal the far end to pause the data

transmission for a short period of time. The pause functionality is applied to all traffic on the link.

The priority flow control (PFC) feature on Cisco NX-OS platforms applies pause functionality to specific

classes of traffic on the Ethernet link. For example, PFC can provide lossless service for the FCoE traffic and

best-effort service for the standard Ethernet traffic using IEEE 802.1p traffic classes.

Fibre Channel traffic requires a lossless transport layer, which means that it requires a data storage protocol

that does not lose a single data packet. A FCoE Forwarder (FCF) communicates with FCoE end devices, such

as converged network adapters (CNAs). The FCF accepts the Fibre Channel frame that is encapsulated in an

Ethernet packet and forwards that packet over a VLAN across an Ethernet network to a remote FCoE end

OL-25809-02

Information About Fibre Channel Over Ethernet, page 1

Fibre Channel Forwarder, page 1

Fibre Channel Bridge, page 2

C H A P T E R

Cisco NX-OS FCoE Configuration Guide for Nexus 7000 and MDS 9500

Table of Contents

Mds 9500 series