How vifs work in Data ONTAP
A virtual interface (vif) is a feature in Data ONTAP that implements link aggregation on your storage system. Vifs provide a mechanism to group together multiple network interfaces (links) into one logical interface (aggregate). After a vif is created, it is indistinguishable from a physical network interface.
The following figure shows four separate network interfaces, e3a, e3b, e3c, and e3d, before they are grouped into a vif.
The following figure shows the four network interfaces grouped into a single vif called Trunk1.
Different vendors refer to vifs
by the following terms:
- Virtual aggregations
- Link aggregations
provide several advantages over individual network interfaces:
- Higher throughput
Multiple interfaces work as one interface.
- Fault tolerance
If one interface in a vif goes down, your storage system stays connected to the network by using the other interfaces.
- No single point of failure
If the physical interfaces in a vif are connected to multiple switches and a switch goes down, your storage system stays connected to the network through the other switches.
- Types of vifs
You can create three different types of vifs on your storage system : single-mode vifs, static multimode vifs, and dynamic multimode vifs.
- Load balancing in multimode vifs
You can ensure that all interfaces of a multimode vif are equally utilized for outgoing traffic. You can use the IP address, MAC address, round-robin, or port based load-balancing methods to equalize traffic.
- Guidelines for configuring vifs
Before creating and configuring vifs, you must follow certain guidelines about the type, MTU size, speed, and media of the underlying interfaces.
- The vif command
You can manage vifs on your storage system by using the vif command. This command enables you to create vifs, add interfaces to vifs, delete interfaces from vifs, view status and statistics of vifs, and destroy vifs.
- Creating a single-mode vif
You can create a single-mode vif in which only one interface is active at a time and the others are ready to take over if the active interface fails. A single-mode vif increases the redundancy for providing more availability.
- Creating a static multimode vif
You can use the vif create command to create a static multimode vif. If you do not specify the type of vif in the vif create command, a static multimode vif is created by default.
- Creating a dynamic multimode vif
With a dynamic multimode vif, all interfaces in the vif are active and share a single MAC address. This logical aggregation of interfaces provides higher throughput than a single-mode vif. Dynamic multimode vifs can detect both loss of link and loss of data flow.
- Adding interfaces to a vif
You can add one or more interfaces to a vif to expand your network. You can add physical interfaces to a vif any time after you create it by using the vif add command.
- Deleting interfaces from a vif
You might have to delete a physical interface from a vif—for example, when the interface needs maintenance or when you want to use the interface for a different purpose. You can use the vif delete command to delete one or more interfaces from a vif.
- Viewing vif status
You can view the current status of a specified vif or all single-mode and multimode vifs on your storage system .
- Viewing vif statistics
You can view the statistics for a specific vif or for all vifs. The statistics include the number of packets received and sent by each vif.
- Destroying a vif
You destroy a vif when you no longer need it or when you want to use the interfaces that form the vif for other purposes. After you destroy the vif, the interfaces in the vif act individually rather than as an aggregate.
- Second-level vifs
If you have more than one multimode vif, you can use the vif create command to group them by creating a second layer of vif called the second-level vif. Second-level vifs enable you to provide a standby multimode vif in case the primary multimode vif fails.
- Second-level vifs in an active/active configuration
In an active/active configuration , you can access data from both storage systems even if one of the storage system in the configuration fails.