Understanding interface configurations for takeover

About interface takeover

When one filer takes over another, it also takes over the interfaces of the failed filer so that it can maintain the same network connections as before the takeover. You can configure interfaces to enable the takeover by using the setup command to configure interfaces for a new filer or the ifconfig command to add interfaces to an existing filer.

Role of network interfaces in a cluster

The role of network interfaces in a cluster is to ensure that each filer in a cluster can assume the identity of its partner on the networks to which the filers are connected:

Each filer in a cluster must have interface attachments to the same collection of subnets.
Each filer must have interfaces that can take over each IP address or interface on the partner filer.

In a noncluster configuration, each interface acts in one role: supporting the identity of the local filer.

In a cluster configuration, each interface can act in one of two roles:

Normal mode, which is the state of the filer when there is no takeover being performed in the cluster.
Takeover mode, in which the partner filer has taken over the failed filer.

The following table shows the role of each interface type in normal and takeover mode.

Interface type	Normal mode	Takeover mode
Dedicated	Supports the identity of the local filer	Supports the identity of the local filer
Standby	Idle	Supports the identity of the failed filer
Shared	Supports the identity of the local filer	Supports the identity of both the local filer and the failed filer

Takeover configurations

You can have two kinds of interface configurations for takeover:

A configuration using separate mirrored network interfaces. You use this configuration with cards that support only single Media Access Control (MAC) addresses. For each interface, you configure a dedicated interface on one filer and a standby interface on the other.
A configuration using NICs with dual MAC capability. A pair of dual-MAC interfaces, one interface to a filer, mirror each other.

FORE/IP and LANE interface configurations

You can configure FORE/IP and LAN Emulation (LANE) interfaces as follows:

You must configure FORE/IP interfaces as dedicated and standby interfaces.
For LANE, you can configure ATM adapter interfaces as mirrored interface pairs, provided that after takeover, a given Emulated LAN is configured only once on an adapter. Otherwise, you must use dedicated and standby interfaces.
You can specify FORE/IP partners using IP addresses or the FORE/IP interface name.
You can specify the LANE partner for an ATM adapter using the ATM adapter interface name.

Interface types and configurations

The following table lists the configurations supported by each type of interface in a cluster.

Interface	Shared	Dedicated	Standby	Partner parameter
Ethernet	X	X	X	IP address or interface name
Gigabit Ethernet		X	X	IP address or interface name
Gigabit Ethernet II	X	X	X	IP address or interface name
FDDI	X	X	X	IP address or interface name
Virtual interface	X	X	X	Virtual interface name
FORE/IP		X	X	IP address or FORE/IP interface name
ATM adapter for LANE1	X2	X	X	ATM adapter interface name

1The OC-12 adapter does not support clusters on F700 series filers.

2ATM adapters in a cluster can be shared for LANE provided that the two adapters do not have Emulated LANs in common.