How are link down and link up traps processed in Spectrum

Document ID : KB000112994
Last Modified Date : 05/10/2018
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Introduction:
This is a tech doc explaining how link down and link up traps are processed in Spectrum and how the alerts such as "BAD LINK DETECTED" and "THE COMMUNICATION LINK IS DOWN" are asserted against the relevant device or interface models.
 
Question:
How are link down and link up traps processed in Spectrum?
 
Environment:
Spectrum 10.x
Answer:
  1. There is additional underlying code used to process the link down and link up traps.
  2. The reason being is because traps are processed at the device level.
  3. In order to process the link up/down traps on the interface model, when the traps are received, Spectrum reads the value of the ifIndex varbind sent with the trap, checks the status of the associated interface model and if ifOper down ifAdmin up, will assert the critical “BAD LINK DETECTED” alarm on the interface model.
  4. In addition, if the AssertLinkDownAlarm attribute id 0x12957 is set to Yes on that interface model, then Spectrum asserts the minor “THE COMMUNICATION LINK IS DOWN” alarm on the associated device model.
 
AssertLinkDownAlarm (0x12957) - Determines if SPECTRUM should generate a yellow alarm on the device model when a link down trap is received for this port.  Valid values are TRUE or FALSE.
 
  1. This minor alarm should be cleared when either the 0x00220102 or 0x00220103 events are generated on the device model. It does not use an event discriminator.
  2. Most customers find this minor alarm to be useless because the critical alarm is asserted on the interface. That is why the AssertLinkDownAlarm attribute id 0x12957 is set to No by default.
  3. One major issue with this alarm is if when the first link down trap is received, the minor alarm is asserted.
  4. While this minor alarm is asserted, if another link down trap is received for a different interface, it does not generate a new alarm, it increments the occurrence value of the existing alarm.
  5. In addition, if a link up trap comes in, it clears the minor alarm even if there is still a critical alarm on a different interface.