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Configuring VLANs for FCoE Traffic on an FCoE Transit Switch

Fibre Channel over Ethernet (FCoE) transit switches transport FCoE traffic on a dedicated VLAN (it cannot be shared with any other type of traffic). You configure a VLAN for FCoE traffic using different procedures on switches that use the Enhanced Layer 2 Software (ELS) configuration style than on switches that don’t use ELS.

Considerations When Configuring FCoE VLANs

When you configure a switch as a Fibre Channel over Ethernet (FCoE) transit switch, you must configure a VLAN that transports only FCoE traffic. FCoE traffic requires a dedicated VLAN and cannot share a VLAN with any other type of traffic.

Because FCoE traffic is tagged traffic, the port (or interface) mode cannot be access mode;you must use either trunk interface-mode for ELS switches or tagged-access port-mode for switches that don’t use ELS.

However, each interface that belongs to an FCoE VLAN must not only transport the tagged FCoE traffic, it must also transport the untagged FCoE Initialization Protocol (FIP) traffic. FIP communicates with the storage area network (SAN) Fibre Channel (FC) switch to set up the FCoE session for the FCoE client.

To transport untagged traffic on a tagged-access or trunk mode interface, the interface must have a native VLAN configured on it. Therefore, each interface that belongs to an FCoE VLAN must also have a native VLAN on it.

There are slight differences in the way you configure a native VLAN on an interface depending on whether the switch uses the Enhanced Layer 2 Software (ELS) configuration style or the original non-ELS CLI.

Note:

FCoE VLANs (any VLAN that carries FCoE traffic) support 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 enables you 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.

Note:

To configure an FCoE VLAN on a QFX3500 switch that you are using as an FCoE-FC gateway, you must also configure an FCoE VLAN interface as described in Configuring an FCoE VLAN Interface on an FCoE-FC Gateway. (Only the QFX3500 switch supports FCoE-FC gateway configuration.)

Configuring an FCoE VLAN includes the following steps:

  • Configure a VLAN to use as a dedicated FCoE VLAN

  • Configure the interface members of the FCoE VLAN.

  • Configure a native VLAN for FIP traffic.

Configure an FCoE VLAN on ELS FCoE Transit Switches

To configure an FCoE VLAN on a switch that uses the Enhanced Layer 2 Software (ELS) configuration style:

  1. Configure a dedicated FCoE VLAN:

    For example, to configure a VLAN named fcoe_vlan with a VLAN ID of 100 as the FCoE VLAN:

  2. Configure the FCoE VLAN on the interface (use ethernet-switching as the family and trunk as the interface mode):

    For example, to configure the interface xe-0/0/10 as a member of the FCoE VLAN fcoe_vlan:

  3. Configure the Ethernet interface membership in the FCoE VLAN:

    For example, to assign the interface xe-0/0/10.0 to the FCoE VLAN named fcoe_vlan:

  4. Configure a native VLAN on the physical Ethernet interface for the untagged FIP traffic:

    For example, to configure the native VLAN on interface xe-0/0/10 with a VLAN ID of 1:

  5. Configure the Ethernet interface as a member of the native VLAN:
    Note:

    The native-vlan-id number must be the same as the native VLAN ID number that you configured on the physical Ethernet interface (see step 4).

    For example, to configure the interface xe-0/0/10 as a member of the native VLAN with the native VLAN ID 1:

Configure an FCoE VLAN on Non-ELS FCoE Transit Switches

To configure an FCoE VLAN on a switch that does not use the ELS CLI:

  1. Configure a dedicated FCoE VLAN:

    For example, to configure a VLAN named fcoe_vlan with a VLAN ID of 100 as the FCoE VLAN:

  2. Configure the FCoE VLAN on the interface (use ethernet-switching as the family and tagged-access as the port mode):

    For example, to configure the interface xe-0/0/10 as a member of the FCoE VLAN fcoe_vlan:

  3. Configure the Ethernet interface membership in the FCoE VLAN:

    For example, to assign the interface xe-0/0/10.0 to the FCoE VLAN named fcoe_vlan:

  4. Configure a native VLAN for the untagged FIP traffic:

    For example, to configure the native VLAN with a VLAN ID of 1:

  5. Assign member interfaces to the native VLAN:

    For example, to configure the interface xe-0/0/10 as a member of the native VLAN with the native VLAN ID 1:

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