IBM Remote Supervisor Adapter II, Installation Manual

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During normal operation, each Remote Supervisor Adapter, ASM processor,
ASM PCI adapter, and ISMP on the ASM interconnect network communicates
with the other processors and adapters on the network. Processors or adapters
that have a modem or Ethernet connection notify the other processors and
adapters that these communication resources are available for use by other
servers on the ASM interconnect network. These resources are then used as
ASM interconnect network resources, enabling Remote Supervisor Adapters,
ASM processors, ASM PCI adapters, and ISMPs on the ASM interconnect
network to send alerts using a modem or the network, even if they do not
have a modem or network connection physically attached.
Note: ISMPs can use the communication resources of a Remote Supervisor
Adapter or Remote Supervisor Adapter II only.
When alerts are generated, they are forwarded to the Remote Supervisor
Adapter II, Remote Supervisor Adapter, ASM processor, or ASM PCI adapter
on the ASM interconnect network that has the communication resources to
forward the alert. If no system on the ASM interconnect network meets the
requirements, the alert is set for transmission if the connection type is
configured or becomes available later.
If multiple modems or network connections exist in the ASM interconnect
network, you cannot specify which system will receive an alert or which will
use its modem or network connection to forward the alert. If an alert is
forwarded to a Remote Supervisor Adapter II, Remote Supervisor Adapter,
ASM processor, or ASM PCI adapter that is unable to deliver the alert (for
example, the modem it is configured to use has failed or the network cannot
resolve the destination IP address), the processor or adapter attempts to
forward the alert to another system on the ASM interconnect network that has
the communication resources to forward the alert.
Alerts are typically sent only once (per connection type), but an alert is
forwarded to another interconnect device if the resources exist on other
interconnect devices in the network. For example, on a three-ASM-processor
network where ASM processor 1 generates a modem alert but does not have a
modem and the two other ASM servers with ASM processors have modems
connected to them, the following situation might occur:
If ASM processor 1 generates an alert and the modem is disconnected from
ASM processor 2 within 45 seconds before ASM processor 1 generates the alert,
ASM processor 1 forwards the alert to ASM processor 2, having previously
determined that ASM processor 2 had an available modem (which is now no
longer available). When ASM processor 2 receives the forwarded alert,
knowing its modem is not available, it determines that a modem is attached to
ASM processor 3 and forwards the alert to ASM processor 3. Therefore,
depending upon the time frame (45 seconds) within which a resource (modem)
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Remote Supervisor Adapter II: Installation Guide