linkDown - CRITICAL

Description

This alarm signifies that the SNMP entity, acting in an agent role, has detected that the ifOperStatus object for one of its communication links is about to enter the down state from some other state (but not from the notPresent state). This other state is indicated by the included value of ifOperStatus.

Repetition

None

Event Codes

ifIndex—A unique value, greater than zero, for each interface. It is recommended that values are assigned contiguously starting from 1. The value for each interface sub-layer must remain constant at least from one re-initialization of the entity's network management system to the next re-initialization.

ifAdminStatus—The desired state of the interface:

• up(1)
• down(2)
• testing(3)
  The testing(3) state indicates that no operational packets can be passed. When a managed system initializes, all interfaces start with ifAdminStatus in the down(2) state. As a result of either explicit management action or per configuration information retained by the managed system, ifAdminStatus is then changed to either the up(1) or testing(3) states (or remains in the down(2) state).

ifOperStatus—The current operational state of the interface:

• up(1)
• down(2)
• testing(3)
• unknown(4)
• dormant(5)
• notPresent(6)
• lowerLayerDown(7)

The testing(3) state indicates that no operational packets can be passed. If ifAdminStatus is down(2) then ifOperStatus should be down(2). 

If ifAdminStatus is changed to up(1), then ifOperStatus should either change or remain in one of the following states:

• Change to up(1) state if the interface is ready to transmit and receive network traffic.
• Change to dormant(5) state if the interface is waiting for external actions (such as a serial line waiting for an incoming connection).
• Remain in the down(2) state if and only if there is a fault that prevents it from going to the up(1) state.
• Remain in the notPresent(6) state if the interface has missing (typically, hardware) components.

Instance Fields

1. Determine what circumstances caused the link to go down, and rectify.
2. Bring the link back up.