16FCoE TransitThe Fibre Channel over Ethernet (FCoE) Transit feature is supported on Ethernet interfaces. When you enable the switch for FCoEtransit, the switch functions as a FIP snooping bridge.NOTE: FIP snooping is not supported on Fibre Channel interfaces or in a switch stack.Fibre Channel over EthernetFCoE provides a converged Ethernet network that allows the combination of storage-area network (SAN) and LAN traffic on aLayer 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 LANtraffic. In addition, DCB provides flexible bandwidth sharing for different traffic types, such as LAN and SAN, according to 802.1ppriority 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 NetworkFibre Channel networks used for SAN traffic employ switches that operate as trusted devices. To communicate with other enddevices 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 andreceives over the network. As a result, the switch can enforce zoning configurations, ensure that end devices use their assignedaddresses, 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 tocreate a Fibre Channel-level of robustness. You can configure ACLs to emulate point-to-point links, providing control over the trafficreceived or transmitted into the switch. To automatically generate ACLs, use FIP snooping. In addition, FIP serves as a Layer 2protocol to:• Operate between FCoE end-devices and FCFs over intermediate Ethernet bridges to prevent unauthorized access to thenetwork and achieve the required security.• Allow transit Ethernet bridges to efficiently monitor FIP frames passing between FCoE end-devices and an FCF. To dynamicallyconfigure 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 storagedevices in a storage area network (SAN). FIP satisfies the Fibre Channel requirement for point-to-point connections by creating aunique 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 sentand received between FCoE end-devices (ENodes) and the FCF. FIP uses its own EtherType and frame format. The followingillustration shows the communication that occurs between an ENode server and an FCoE switch (FCF).The following table lists the FIP functions.308 FCoE Transit
