Product Documentation

Redundant Interface Set

Oct 19, 2016

A redundant interface set is a set of interfaces where one of the interfaces is active and the remaining ones are standby. If the active interface fails, one of the standby interfaces takes over and becomes active.

The following are the main benefits of using redundant interface sets:
  • A redundant interface set ensures connection reliability between the NetScaler appliance and a peer device by providing back up links between them.
  • Unlike link redundancy using LACP, no configuration is required on the peer device for a redundant interface set. To the peer device, redundant interface set appear as individual interfaces and not as a set or collection.
  • In an high availability configuration (HA), redundant interface sets can minimize the number the HA failovers.

A link redundant set is specified in LR/X notation, where X can range from 1 to 4. For example, LR/1.

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Redundant Interface Set was formerly known as 'NIC bundling' when first introduced in 10.5 release. 

How Redundant Interface Set Works

For a redundant interface set, the NetScaler appliance derives a MAC address on the basis of an internal algorithm and assigns it to the redundant interface set. This MAC address is shared by all the member interfaces and is used only by the active interface at a time. The active interface broadcasts GARP messages, which contains the MAC address assigned to the redundant interface set and not the interface's own physical MAC address. When the current active interface fails and is taken over by another interface, the new active interface sends GARP messages. The peer device updates its forwarding table with the new active interface information. The standby interfaces do not send any GARP messages. The standby interfaces do not send any packets and they drop any packets they receive.

In a redundant interface set, selection of the member interface as active is based on either of the following factors:
  • Redundant interface priority. This is a parameter of an interface and it defines the priority of the interface in a redundant interface set for the active member selection. This parameter specifies a positive integer. Lower the value higher the priority of active member selection. The member interface with the highest priority (lowest value) is selected as the active interface of the redundant interface set.
  • Binding order of the member interfaces. If all the member interfaces have the same redundant interface priority, the member interface that was bound first to the redundant interface set is selected as the active interface of the redundant interface set.
In a redundant interface set, active interface selection is triggered in one of the following events:
  • When the current active interface fails or you disable it.
  • When you set the priority of a standby interface to a value lower than that of the current active interface. The standby interface takes over as the active interface.
  • When you bind an interface whose priority is lower than that of the current active interface. The newly bound interface takes over as the active interface.

Points to Consider for Configuring Redundant Interface Sets

Updated: 2015-03-2

Consider the following points before you configure a redundant interface set:
  • In a high availability configuration, redundant interface set configurations do not propagate or synchronize to the secondary node.
  • In a NetScaler cluster configuration, redundant interface sets are not supported.
  • You can configure a maximum of four redundant interface sets.
  • You can bind a maximum of 16 interfaces to a redundant interface set.
  • Member interfaces of a redundant interface set cannot be bound to another redundant interface set.
  • Member interfaces of a redundant interface set cannot be bound to a LA channel.

Configuration Steps

Configuring redundant interface set on a NetScaler appliance consists of the following tasks:
  • Create a redundant interface set. Use the channel command operation for creating a redundant interface set.

    A link redundant set is specified in LR/X notation, where X can range from 1 to 4. For example, LR/1.

  • Bind interfaces to the redundant interface set. Associate the desired interfaces with the redundant interface set. An interface cannot be a part of multiple redundant interface sets.
  • (Optional) Set a redundant interface priority on the member interface. Use the interface command operation for setting the redundant interface priority on a desired member interface of a redundant interface set.

To create a redundant interface set by using the command line interface

At the command prompt:

  • add channel <ID>
  • show channel <ID>

To bind interfaces to a redundant interface set by using the command line interface

At the command prompt:

  • bind channel <ID> <ifnum>
  • show channel <ID>

To set a redundant interface priority of an interface by using the command line interface

At the command prompt:

  • set interface <ID> -lrsetpriority <positive_integer>
  • show interface <ID>

Example

In the following example, redundant interface set LR/1 is created, and interfaces 1/1, 1/2, 1/3, and 1/4 are bound to LR/1. The redundant interface priority is set to a default value of 1024 for all these member interfaces. Output of the show channel command displays that the interface 1/1 is the current active interface for the redundant interface set lr/1.

> add channel lr/1 
 Done 
> bind channel lr/1 1/1 1/2 1/3 1/4 
 Done 
> show channel 
1)    Interface LR/1 (Link Redundant) #23 
        flags=0x100c020 <ENABLED, UP, LINKREDUNDANT, UP, HAMON, 802.1q> 
        MTU=1500, native vlan=1, MAC=36:97:a2:b7:6b:a9, uptime 0h00m00s 
        Requested: media NONE, speed AUTO, duplex NONE, fctl OFF, 
                 throughput 0 
        Actual: throughput 1000 
        LLDP Mode: NONE, 
        RX: Pkts(1) Bytes(52) Errs(0) Drops(1) Stalls(0) 
        TX: Pkts(2) Bytes(84) Errs(0) Drops(4) Stalls(0) 
        NIC: InDisc(0) OutDisc(0) Fctls(0) Stalls(0) Hangs(0) Muted(0) 
        Bandwidth thresholds are not set. 
                1/1: UTP-1000-FULL-OFF          UP  0h14m06s    LR Active Member 
                1/2: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
                1/3: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
                1/4: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
Done

In the following example, redundant interface priority of the member interface 1/4 is set to 100, which is lower than the set redundant interface priority of all the other member interfaces of LR/1.

Output of the show channel command displays that the interface 1/4 is the current active interface for the redundant interface set LR/1.

> set interface 1/4 -lrsetPriority 100 
Done 
> show channel 
1)      Interface LR/1 (Link Redundant) #23 
        flags=0x100c020 <ENABLED, UP, LINKREDUNDANT, UP, HAMON, 802.1q> 
        MTU=1500, native vlan=1, MAC=36:97:a2:b7:6b:a9, uptime 0h00m00s 
        Requested: media NONE, speed AUTO, duplex NONE, fctl OFF, 
                 throughput 0 
        Actual: throughput 1000 
        LLDP Mode: NONE, 
        RX: Pkts(1) Bytes(52) Errs(0) Drops(1) Stalls(0) 
        TX: Pkts(2) Bytes(84) Errs(0) Drops(4) Stalls(0) 
        NIC: InDisc(0) OutDisc(0) Fctls(0) Stalls(0) Hangs(0) Muted(0) 
        Bandwidth thresholds are not set. 
                1/1: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
                1/2: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
                1/3: UTP-1000-FULL-OFF          UP  0h14m06s    LR Inactive Member 
                1/4: UTP-1000-FULL-OFF          UP  0h14m06s    LR Active Member 
Done