Wide Area Link Monitoring

Contents
casp1032
Contents
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polls any ports connected to a WA_Link model for status automatically. This polling is controlled by the PollingStatus and Polling_Interval of the WA_Link model.
If the PollingStatus of a WA_Link model is TRUE, and its Polling_Interval is non-zero,
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automatically makes the pipes that are connected to a WA_Link "live" and sets the PollPortStatus for port models to TRUE. The live pipe lets you visually verify that
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is monitoring the status of the connected ports.
If you disable the live pipe but leave the PollingStatus of the WA_Link set to TRUE, the Polling_Interval set to a non-zero number, and the ports’ PollPortStatus set to TRUE,
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continues to monitor the status of the ports.
WA_Link models can only represent point-to-point connections, such as T1 and T3 lines. No more than two devices can be connected to it at a time.
LinkFaultDisposition
The LinkFaultDisposition setting provides control and flexibility over fault alarming. When a wide area connection goes down, alarms can be generated on ports and on the link model. You can set the LinkFaultDisposition (0x129e2) attribute from the WA_Link model Attributes tab.
LinkFaultDisposition can be set to one of the following three modes:
  • BothPortsAndLink
    If set to BothPortsAndLink, alarms are generated on both the connected ports and on the link model. This is the default setting.
  • PortsOnly
    If set to PortsOnly, only the connected ports are alarmed, and the WA_Link is suppressed.
  • LinkOnly
    If set to LinkOnly, only the WA_Link model will be alarmed, and the ports will be suppressed.
Wide Area Link Monitoring Scenarios
Consider the sample WA_Link network topology shown in the following diagram:
spec--wa_link_diagram_OTH
The following tables illustrate two possible WA_Link monitoring scenarios for this topology.
Scenario 1: Link Goes Down, Device B Loses Contact
LinkFaultDisposition
Port 1 Condition
WA_Link Condition
Port 2 Condition
BothPortsAndLink
Red
Red
Gray
PortsOnly
Red
Gray
Gray
LinkOnly
Gray
Red
Gray
If the Suppress Linked Port Alarms setting is set to TRUE, then the alarm on the upstream port will be suppressed, even if Link Fault Disposition is set to BothPortsAndLink. If Link Fault Disposition is set to Ports Only, and the Suppress Linked Port Alarms setting is set to TRUE,
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generates an alarm on the Port model.
Scenario 2: Link Goes Down, Device B Remains Reachable
LinkFaultDisposition
Port 1 Condition
WA_Link Condition
Port 2 Condition
BothPortsAndLink
Red
Red
Red
PortsOnly
Red
Gray
Red
LinkOnly
Gray
Red
Gray
If the Suppress Linked Port Alarms setting is set to TRUE, then only one of the ports is alarmed (red). The other port will be suppressed (gray). If Link Fault Disposition is set to Ports Only, and the Suppress Linked Port Alarms setting is set to TRUE,
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generates an alarm on the Port model.
Wide Area Link Modeling Best Practices
When you model a Wide Area Link, be sure to supply the IP address for the Network_Address parameter. As a best practice, supply values for the WA_Link model Network_Address and Network_Mask attributes based on the subnet of the connected router interfaces. In a proxy environment, the "real" and "proxy" links must have the same value for Network_Address.
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relies on the Network_Address (0x12d7f) attribute of a WA_Link to find duplicate WA_Link models and to collapse proxies into a single icon.The Network_Address is the only unique attribute that can be used to find duplicate WA_Links. However, this attribute is not automatically populated by
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unless the WA_Link models are created by Discovery. When you manually create WA_Links, the Network_Address and Network_Mask attributes are not automatically populated, even when they are connected to router interface models with valid IP addresses.
In our testing, we have found that the Global Collection topology view does not collapse proxied WA_Link models correctly if the Network_Address parameter is not configured.
Set the Network_Address attribute of the WA Link model to the network ID of the subnet to which the interface belongs. For example, a serial interface has an IP address of 10.253.9.2 and a subnet mask of 255.255.255.252. Set the Network_Address attribute of the WA Link to 10.253.9.0 (10.253.9.2 with subnet mask 255.255.255.252).
In addition, do not simply draw pipes between the router and WA_Link icons. Proper WA_Links require a nested WA_Segment. In addition, an interface model on each router must be connected to the WA_Segment (and not to the WA_Link). This modeling paradigm enables
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to establish fully resolved connections. It also enables the proper display of pipes in the Global Collection topology view.