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HP OpenVMS System Manager's Manual, Volume 2:... |
Managing the Local Area Network (LAN) Software |
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The system manager defines and creates a LAN Failover set using LANCP utility program. A failover set consists of one adapter that is used for LAN traffic and one or more adapters that remain idle. If the active adapter fails, one of the idle set members automatically takes over, allowing for continuous operation.
LAN Failover integrates multiple network devices on the same LAN segment into a failover set and presents it as a single virtual device, LLc, to the LAN applications (where c is a user-specified alphabetic character uniquely identifying the LAN virtual device).The virtual LAN driver, Lldriver, supports LAN Failover. Lldriver provides the standard IEEE 803 interfaces to the higher software layers, maintains the logical groupings of all the adapters in a failover set, and transfers I/O to the active physical port driver.
One network device in the set is active while the others remain idle. If the active device fails, Lldriver selects one of the idle devices from the failover set to become active. The physical address and multicast addresses of the virtual device remain the same, allowing for continuous operation of LAN applications.
LAN Failover requires that redundant network interface cards be on the same local area network. The network interface cards supported by LAN Failover are the DEGPA, the DEGXA, and the DE600 series.
Detecting Network Connectivity Failures
LAN Failover provides a mechanism to protect against certain kinds of network connectivity failures. The virtual and physical LAN drivers detect network interface card (NIC) failures and failures that exist between the NIC and the switch.
Restrictions for Using LAN Failover
Restrictions for using LAN Failover are the following:
The LAN volatile and permanent device databases contain a single entry for each LAN device that exists on the system. The virtual device, LLc, is added to these databases through LANCP when the system manager creates a LAN Failover set.
To enter the LLc device into the LAN permanent device database or to modify an existing entry, enter the LANCP command DEFINE DEVICE LLc using the following syntax:DEFINE DEVICE LLc[/qualifiers]
This command allows the settings to take effect on subsequent boots.
Before a physical adapter can be added to a failover set, all users on that adapter must be stopped.
Creating
a LAN Failover Set
The virtual device, LLc, is created when you create a LAN
Failover set. To create a LAN Failover set, enter the LANCP command
SET DEVICE LLc using the following syntax:SET DEVICE LLc/FAILOVER_SET=(device-name[,...])
In this command, supply the LAN physical device name for the device-name; for example:
LANCP> SET DEVICE LLA/FAILOVER_SET=(EWA,EIA,EWB)Removing
a LAN Failover Set
To remove a LAN Failover set, enter the LANCP command SET
DEVICE LLc using the following syntax:SET DEVICE LLc/NOFAILOVER_SET=(device_name[,...])
In this command, supply the LAN physical device name for the device-name; for example:
LANCP> SET DEVICE LLA/NOFAILOVER_SET=(EWB)This command fails if one of the specified devices is the active physical device.
Setting
the Priority of a LAN Failover Participant
To give preference to a physical LAN device when you select
the active participant of a LAN Failover set, enter the LANCP command
SET DEVICE/PRIORITY command using the following syntax:SET
DEVICE device-name/PRIORITY=value
In this command, supply the LAN physical device name for the device-name and an integer for the value parameter; for example:
LANCP> SET DEVICE EIA/PRIORITY=20When selecting the active participant, the system gives preference to the device with the highest priority.
Enabling
LAN Failover
Enabling a LAN Failover device establishes the physical address
of the virtual device and selects the active participant of the
LAN Failover set.
To enable LAN Failover, enter the LANCP command SET DEVICE LLc using the following syntax:SET DEVICE LLc/ENABLE
This command fails if a LAN Failover set does not exist.
Disabling
LAN Failover
Disabling a LAN Failover device disassociates the virtual
device from a physical device. This allows all physical devices
to be removed from the LAN Failover set.
To disable LAN Failover, enter the LANCP command SET DEVICE using the following syntax:SET DEVICE LLc/DISABLE
This command fails if the virtual device has active users.
Displaying
LAN Failover Characteristics
To display LAN Failover status, enter the LANCP command SHOW
DEVICE LLc using the following syntax:SHOW DEVICE LLc/CHARACTERISTICS
The display shows the characteristics that are specific to LAN Failover for a particular node, as shown in the following example:
Device Characteristics LLAO:
Value Characteristic
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"EIA" Failover device (active)
"EWA" Failover device
Enabled/Active Logical LAN state
Validating
a LAN Failover Set
The network devices associated with a LAN Failover set must
provide physically redundant paths on the same local network for
LAN Failover to function correctly. Since networks are highly stable,
the active member of a LAN Failover set might not change often.
However, when the active member does change, it is crucial that
the idle NICs have been set up properly. The system manager can
validate each member of the failover set by simulating LAN failures
using the LANCP qualifier /SWITCH. The /SWITCH qualifier simulates
a network failure on the active device and selects another device
from the failover set to be the active device.
To simulate a LAN failure, enter the LANCP command SET DEVICE LLc using the following syntax:
SET DEVICE LLc/SWITCH
Illustration
of LAN Failover
The following figure illustrates LAN Failover.
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Figure 1 LAN Failover |
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