Configuring an FCoE LAG
SUMMARY A Fibre Channel over Ethernet (FCoE) link aggregation group (LAG) is a special LAG that enables you to transport FCoE traffic and regular Ethernet traffic across the same link aggregation bundle. This procedure shows how you configure an FCoE LAG with enhanced FIP snooping scaling enabled (scaling up to 2,500 sessions) or with enhanced FIP snooping scaling disabled (which reduces the number of supported FIP snooping sessions to 376).
How to Configure an FCoE LAG
A Fibre Channel over Ethernet (FCoE) link aggregation group (LAG) is a special LAG that enables you to transport FCoE traffic and regular Ethernet 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 a series of communications between two devices might use different physical links in the LAG for different transmissions.
However, FCoE traffic requires a point-to-point link (or a virtual point-to-point link) between the FCoE device and the Fibre Channel (FC) storage area network (SAN) switch. This requirement means that communication between an FCoE device and a QFabric system Node device must use the same physical link in a LAG to maintain the virtual point-to-point connection.
An FCoE LAG solves the problem by ensuring that the same LAG link is used for communication between an FC SAN switch and a given FCoE device across a QFabric system Node device, preserving point-to-point link emulation. At the same time, regular Ethernet traffic (traffic that is not FCoE traffic) on the LAG is distributed across member interfaces in the same way as on a standard LAG. FCoE traffic is treated properly in terms of maintaining a virtual point-to-point link with the FC SAN, and regular Ethernet traffic enjoys the usual LAG benefits of load balancing and link redundancy.
Configuring a LAG as an FCoE LAG does not provide link redundancy for FCoE traffic, and does not load balance FCoE traffic.
On FCoE-FC gateway Fibre Channel fabrics (fc-fabrics) that are untrusted, if you configure an FCoE LAG, you must also disable enhanced FIP snooping scaling (scaling up to 2,500 sessions), which reduces the number of supported FIP snooping sessions to 376 sessions. On an FCoE-FC gateway, disabling enhanced FIP snooping scaling is global to the Node device. Trusted fc-fabrics on an FCoE-FC gateway support enhanced FIP snooping scaling.
You can configure an FCoE LAG with enhanced FIP snooping scaling enabled or with enhanced FIP snooping scaling disabled.
The steps required to create the FCoE LAG are:
Configure an FCoE LAG interface.
Assign the Ethernet interfaces connected to the FCoE device to the FCoE LAG.
Configure FIP snooping.
In addition to configuring the FCoE LAG and FIP snooping scaling, you also must do the following:
Configure a dedicated FCoE VLAN for the FCoE traffic.
Configure a native VLAN for the untagged FIP traffic.
Enable FIP snooping on the FCoE VLAN.
Configure the FCoE LAG interface membership in the FCoE VLAN and the native VLAN.
For FCoE-FC gateway switches, configure a Layer 3 FCoE VLAN interface, and add the FCoE VLAN interface to the Fibre Channel fabric.
For FCoE-FC gateway switches, configure the fc-fabric as an FCoE trusted fabric if you are using enhanced FIP snooping scaling (and if the FCoE traffic is trusted).
Example: Configuring an FCoE LAG on a Redundant Server Node Group includes a full example of this configuration.
Configure an FCoE LAG When Enhanced FIP Snooping Scaling is Enabled
This configuration procedure shows how you configure an FCoE LAG when you can use enhanced FIP snooping scaling, such as when the FCoE-FC gateway fabrics are trusted or on an FCoE transit switch.
Configure an FCoE LAG When Enhanced FIP Snooping Scaling Must be Disabled
This configuration procedure shows how you configure an FCoE LAG when you need to disable enhanced FIP snooping scaling, for example, when an FCoE-FC gateway fabric is untrusted.