Reference Guide

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FCoE Transit
The Fibre Channel over Ethernet (FCoE) Transit feature is supported on the S4820T switch on Ethernet interfaces. When
you enable the switch for FCoE transit, the switch functions as a FIP snooping bridge.
NOTE: FIP snooping is not supported on Fibre Channel interfaces or in a S4820T switch stack.
Fibre Channel over Ethernet
FCoE provides a converged Ethernet network that allows the combination of storage-area network (SAN) and LAN traffic
on a Layer 2 link by encapsulating Fibre Channel data into Ethernet frames.
FCoE works with the Ethernet enhancements provided in data center bridging (DCB) to support lossless (no-drop) SAN
and LAN traffic. In addition, DCB provides flexible bandwidth sharing for different traffic types, such as LAN and SAN,
according to 802.1p priority classes of service. DCBx should be enabled on the system before the FIP snooping feature is
enabled. For more information, refer to the Data Center Bridging (DCB) chapter.
Ensure Robustness in a Converged Ethernet Network
Fibre Channel networks used for SAN traffic employ switches that operate as trusted devices. To communicate with
other end devices attached to the Fibre Channel network, end devices log into the switch to which they are attached.
Because Fibre Channel links are point-to-point, a Fibre Channel switch controls all storage traffic that an end device
sends and receives over the network. As a result, the switch can enforce zoning configurations, ensure that end devices
use their assigned addresses, and secure the network from unauthorized access and denial-of-service (DoS) attacks.
To ensure similar Fibre Channel robustness and security with FCoE in an Ethernet cloud network, FIP establishes virtual
point-to-point links between FCoE end-devices (server ENodes and target storage devices) and FCoE forwarders (FCFs)
over transit FCoE-enabled bridges.
Ethernet bridges commonly provide ACLs that can emulate a point-to-point link by providing the traffic enforcement
required to create a Fibre Channel-level of robustness. You can configure ACLs to emulate point-to-point links, providing
control over the traffic received or transmitted into the switch. To automatically generate ACLs, use FIP snooping. In
addition, FIP serves as a Layer 2 protocol to:
• Operate between FCoE end-devices and FCFs over intermediate Ethernet bridges to prevent unauthorized
access to the network and achieve the required security.
• Allow transit Ethernet bridges to efficiently monitor FIP frames passing between FCoE end-devices and an FCF.
To dynamically configure ACLs on the bridge to only permit traffic authorized by the FCF, use the FIP snooping
data.
FIP enables FCoE devices to discover one another, initialize and maintain virtual links over an Ethernet network, and
access storage devices in a storage area network (SAN). FIP satisfies the Fibre Channel requirement for point-to-point
connections by creating a unique virtual link for each connection between an FCoE end-device and an FCF via a transit
switch.
FIP provides functionality for discovering and logging into an FCF. After discovering and logging in, FIP allows FCoE
traffic to be sent and received between FCoE end-devices (ENodes) and the FCF. FIP uses its own EtherType and frame
format. The following illustration shows the communication that occurs between an ENode server and an FCoE switch
(FCF).
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