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Understanding VIFs

Understanding VIFs. Rick Triana Professional Services Consultant. About VIFs. 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).

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Understanding VIFs

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  1. Understanding VIFs Rick Triana Professional Services Consultant

  2. About VIFs 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 being created, a vif is indistinguishable from a physical network interface. Different vendors also refer to vifs using these terms: • Virtual aggregations • Link aggregations • Trunks • EtherChannel • NIC Teaming

  3. Advantages of VIFs Using vifs provides several advantages over using individual network interfaces, such as the following: • Higher throughput - Multiple interfaces work as one interface. • Fault tolerance - If one interface in a vif goes down, your storage system can stay connected to the network using the other interfaces. • No single point of failure - If the physical interfaces in a vif are connected to different switches and a switch goes down, your storage system stays connected to the network through the other switches.

  4. Filer interfaces before grouping into a vif • The following figure shows four separate storage system interfaces, e3a, e3b, e3c, and e3d, before grouping into a vif.

  5. Filer interfaces after grouping into a vif • The following figure shows the four storage system interfaces grouped into a single vif called Trunk1.

  6. Types of VIFs • There are three kinds of vifs (ok four): • Single-mode • Multimode • static • dynamic (LACP) • Second Level VIF

  7. Single-Mode VIF • In a single-mode vif, only one of the interfaces in the vif is active. The other interfaces are on standby, ready to take over if the active interface fails. • Failure means that the link status of the interface is down, which signals that the interface has lost connection with the switch. • There can be more than one interface on standby in a single-mode vif. • If an active interface fails, your storage system randomly picks one of the standby interfaces to be the next active link. • The active link is monitored and link failover is controlled by the storage system; therefore, single-mode vif does not require any switch configuration or a switch that supports link aggregation. • All interfaces in a single-mode vif share a common Media Access Control (MAC) address.

  8. Example of Single-Mode VIF • In the following figure, e0 and e1 are part of the SingleTrunk1 singlemode vif. The active interface, e0, fails. The standby e1 interface takes over and maintains the connection to the switch.

  9. MultiMode VIF • All interfaces in the VIF are active and share a single MAC address. • Provides higher throughput than a single-mode VIF (Load Balancing). • Can recover from a failure of up to (n-1) interfaces (Link Failover). • A multimode VIF requires a switch that supports Etherchannel. • All interfaces of the VIF must be connected to the same switch • The multimode VIF implementation in Data ONTAP is in compliance with IEEE 802.3ad (static). • Dynamic 802.3ad, also known as Link Aggregation Control Protocol (LACP), is NOW supported for multimode VIFs starting with Ontap 7.2.1 and above. • Additionally, Port Aggregation Protocol (PAgP), Cisco’s proprietary link aggregation protocol, is NOTsupported.

  10. Example of MultiMode VIF • In the following figure, e0, e1, e2, and e3 are part of the MultiTrunk1 multimode vif. • All four interfaces in the MultiTrunk1 multimode vif are active.

  11. Notes on dynamic VIF (LACP) • The dynamic multimode vif implementation in Data ONTAP is in compliance with IEEE802.3ad (dynamic), also known as LACP. • Dynamic multimode vifs can detect not only the loss of link status, but also a loss of data flow. Thus, dynamic multimode vifs are compatible with high-availability environments. • However, dynamic multimode vifs have some special requirements: • Dynamic multimode vifs must be connected to a switch that supports LACP. • Dynamic multimode vifs must be configured as first-level vifs. • Dynamic multimode vifs should be configured to use the IP-based loadbalancing method.

  12. Second Level VIF • You group multiple multimode vifs to obtain 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. You can use second-level vifs on a single storage system or in a cluster. • NOTE: You cannot use LACP vifs as second-level vifs.

  13. Example of Second Level VIF • In the following illustration, Secondlev is the single-mode second-level vif comprising the Firstlev1 and Firstlev2 vifs. • Firstlev1 is initially the active interface; if Switch 1 drops both links, Switch 2 and Firstlev2 take over and maintain the connection to the network

  14. Summary of VIFs • Single-Mode VIF (Good) • Advantages • Provides Link Failover. • Can span multiple switches. • Easy to configure. No special switch configuration required. • Minimum of two interfaces required. • Disadvantage • No load balancing.

  15. Summary of VIFs • Multi-Mode VIF (Better) • Advantages • Provides Link Failover • Provides Load Balancing • Two or more interfaces required • Disadvantages • More complex. Must configure Etherchannel on switch • Does not span switches. Switch is SPOF.

  16. Summary of VIFs • Second-Level VIF (Best) • Advantages • A NetApp Best Practice • Provides Link Failover • Provides Load Balancing • Spans multiple switches eliminating switch as SPOF • Disadvantages • Even more complex. Must configure Etherchannel on multiple switches. • Minimum of four interfaces required. (Done this with three interfaces).

  17. Additonal Notes TOE Limitiations LACP Notes Guidelines for creating & configuring VIF Example configs

  18. Notes about 10GbE TOE NIC limitations The 10GbE TOE NIC cards have a number of limitations. They include: • Multimode vif limited to two (2) 10GbE TOE NICs • LACP not supported with 10GbE TOE NICs • TOE functionality disabled on 10GbE NIC in vif

  19. LACP Notes • The dynamic multimode vif implementation in Data ONTAP is in compliance with IEEE 802.3ad (dynamic), also known as LACP. Dynamic multimode vifs can detect not only the loss of link status, but also a loss of data flow. Thus, dynamic multimode vifs are compatible with high-availability environments. However, dynamic multimode vifs have some special requirements: • Dynamic multimode vifs must be connected to a switch that supports LACP. • Dynamic multimode vifs must be configured as first-level vifs. • Dynamic multimode vifs should be configured to use the IP-based load- balancing method.

  20. Guidelines for creating and configuring vifs • You can group up to 16 physical Ethernet interfaces on your storage system to obtain a vif. • The network interfaces that are part of a vif do not have to be on the same network adapter, but it is best that all network interfaces be full-duplex. • You cannot include a virtual LAN (VLAN) interface in a vif. • The interfaces that form a vif must have the same Maximum Transmission Unit (MTU) size. • You can use the ifconfig command to configure the MTU size on the interfaces of a vif. You need to configure the MTU size only if you are enabling jumbo frames on the interfaces. • Do not mix interfaces of different speeds or media in the same multimode vif. • Some switches might not support multimode link aggregation of ports configured for jumbo frames.

  21. Example Configurations Single-Mode VIF: vif create single VIF1 e0 e1 MultiMode VIF (static): vif create multi mult1 e0a e0b LACP MultiMode VIF (dynamic): vif create lacp VIF3 e1a e2a Second Level VIF: vif create multi multi1 e0a e0b vif create multi multi2 e0c e0d vif create single multi1 multi2

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