Configuring Link Aggregation Devices on VNX » cyberfella ltd, since 2012.

If you intend migrating data to CIFS on VNX, then the networking should be set up to be resistant to failure. This is achieved by creating virtual lacp (link aggregation) or fsn (fail safe network) devices on the vnx and then assigning your IP addresses to those virtual network devices instead of physical ones. The virtual network devices use two or more underlying physical network devices for resilience, and be aware that lacp needs to be set up on the switch ports for it to all work too.

The main difference to be aware of regarding lacp and/or fsn devices is that lacp devices can move between multiple active datamovers, whereas fsn’s live on only one datamover. You also run into trouble later on if you create an fsn out of multiple lacp devices which are connected to different vlans.

Personally, I’m yet to use an fsn device, and seem to usually end up just creating interfaces (assigning IP addresses) to multiple, separate lacp devices in practice.

Another gotcha, and hence the reason for this blog post, is that Unisphere will let you create lacp devices on active datamovers, but not on your standby datamover, yet if you want lacp devices configuration to failover to a standby, the networking configuration has to be the same!

So, in summary, the safest way to set things up correctly, is to use the command line.

In this example, I’m specificly configuring an lacp device on a standby datamover. You can tweak the syntax accordingly to create devices on active datamovers or use unisphere.

Log onto VNX via SSH

List all Devices (Physical and Virtual)

server_sysconfig server_4 -pci

Create lacp Device

server_sysconfig server_4 -virtual -name lacp-3 -create trk -option “device=cge-2-0,cge-2-1 protocol=lacp lb=ip”

Check device exists and LACP is up

Either refresh Unisphere or use the command

server_ssyconfig server_4 -virtual -info lacp-3

If LACP column shows Down, then lacp has not been configured on the physical ports on the switch.

Delete the device if necessary

Compare the config of the device with that of an lacp device on your primary datamover to check the correct load balancing mode has been used (mac/ip/tcp). If you need to delete the device and start over, use Unisphere or the command

server_sysconfig server_4 -virtual -delete lacp-3

Assigning IP address to the lacp device

Beyond the scope of this blog post, but logically the next step would be to assign an IP address to the new network device on your primary active datamover. This can be done easily creating an Interface using Unisphere. Subsequently, when you create a CIFS Server, you’d then choose this interface as it’s connection to the network, safe in the knowledge it has more than one underlying physical connection. Needless to say, the ports on any single set of ports on the datamover should go off to a different blade on the switch.

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