FCoE traffic should use a VLAN dedicated only to FCoE traffic. The Ethernet interfaces that connect to FCoE devices must include a native VLAN to transport FIP traffic, because devices exchange FIP VLAN discovery and notification frames as untagged packets. As a result, we recommend that you keep the native VLAN separate from the VLANs that carry the FCoE traffic. Other types of untagged traffic might use the native VLAN.
Keep the following in mind when setting up FCoE VLANs on FCoE transit switches :
* When a switch acts as a transit switch, the VLANs you configure for FCoE traffic can use any of the switch ports because the traffic in both directions is standard Ethernet traffic, not native FC traffic.
* On switches and QFabric system Node devices that do not use Enhanced Layer 2 software (ELS), you use only one CLI command to configure the native VLAN on the FCoE interfaces that belong to the FCoE VLAN :
set interfaces interface-name unit unit family ethernet-switching native-vlan-id native-vlan-id
On switches that use ELS software, you use two CLI commands to configure a native VLAN on FCoE interfaces:
* Configure the native VLAN on the interface : set interfaces interface-name native-vlan-id vlan-id
* Configure the port as a member of the native VLAN : set interfaces interface-name unit unit family ethernet-switching native-vlan-id vlan-id
* An FCoE VLAN (any VLAN that carries FCoE traffic) supports only Spanning Tree Protocol (STP) and link aggregation group (LAG) Layer 2 features.
* FCoE traffic cannot use a standard LAG because traffic might be hashed to different physical LAG links on different transmissions. This breaks the (virtual) point-to-point link that Fibre Channel traffic requires. If you configure a standard LAG interface for FCoE traffic, FCoE traffic might be rejected by the FC SAN.
* QFabric systems support a special LAG called an FCoE LAG, which you can use to transport FCoE traffic and regular Ethernet traffic (traffic that is not FCoE traffic) across the same link aggregation bundle. Standard LAGs use a hashing algorithm to determine which physical link in the LAG is used for a transmission, so communication between two devices might use different physical links in the LAG for different transmissions. An FCoE LAG ensures that FCoE traffic uses the same physical link in the LAG for requests and replies in order to preserve the virtual point-to-point link between the FCoE device converged network adapter (CNA) and the FC SAN switch across the QFabric system Node device. An FCoE LAG does not provide load balancing or link redundancy for FCoE traffic. However, regular Ethernet traffic uses the standard hashing algorithm and receives the usual LAG benefits of load balancing and link redundancy in an FCoE LAG.
