ATM Configuration and Troubleshooting Guide

Conﬁguring EMS High Availability over ATM

Types of Recovery

Chapter 6 93

Types of Recovery

EMS HA-ATM consists of local recovery with EMS and remote recovery

with MC/ServiceGuard and EMS. Each of these recovery types is

described next.

Local Recovery

The EMS HA-ATM functionality manages local recovery of an ELAN

interface, ATM adapter, or link failure.

The EMS HA-ATM functionality performs the following tasks:

• Monitors ELAN interfaces to detect failure.

• Performs local recovery by transferring from one local ELAN

interface to another if a failure occurs.

You can conﬁgure a delay period for local recovery. The delayperiod

speciﬁes the amount of time the hatmmon monitor must wait before it

begins local recovery of an ELAN interface that has failed. If the

ELAN interface becomes operational during the delay period, the

delay period is ended and no local recovery occurs. If the delay period

expires and the interface is still down, hatmmon begins a local

recovery of the interface. Note that we recommend you do not use

this feature unless you are using specialized ATM equipment (for

example, a switch) that requires such a delay in the start of recovery.

• Logs events, in particular when the status of an active ELAN

interface changes from “up” to “down” (for example, ATM link and

ELAN failure).

Remote Recovery (with MC/ServiceGuard)

Remote recovery in an ATM network is provided by using

MC/ServiceGuard facilities over ATM to build a High Availability cluster

composed of systems linked together over an ATM network.

MC/ServiceGuard must run on every system in the cluster, because it

manages remote recovery and migration of the ATM applications and

services between resources. Each of these applications and services is