isisVersionSkew

ISIS-MIB::isisVersionSkew #

A notification sent when we receive a Hello PDU from an IS running a different version of the protocol. This notification includes the header of the packet, which may help a network manager identify the source of the confusion. The agent must throttle the generation of consecutive isisVersionSkew notifications so that there is at least a 5-second gap between notifications of this type. When notifications are throttled, they are dropped, not queued for sending at a future time.

Variables #

  • isisNotificationSysLevelIndex
  • isisNotificationCircIfIndex
  • isisPduProtocolVersion
  • isisPduFragment

Definitions #

isisNotificationSysLevelIndex
The system level for this notification.
isisNotificationCircIfIndex
The identifier of this circuit relevant to this notification.
isisPduProtocolVersion
Holds the Protocol version reported in PDU we received.
isisPduFragment
Holds up to 64 initial bytes of a PDU that triggered the notification.

Here is a runbook for the ISIS-MIB::isisVersionSkew SNMP trap:

Meaning #

The ISIS-MIB::isisVersionSkew trap is generated when a network device receives a Hello PDU from another Intermediate System (IS) running a different version of the IS-IS protocol. This trap is sent to notify the network administrator of a potential configuration issue or incompatibility between devices.

Impact #

The impact of this trap is that it may indicate a problem with IS-IS protocol interoperability between devices, which can lead to connectivity issues or routing instability in the network. If left unaddressed, this issue can cause network outages, packet loss, or delays.

Diagnosis #

To diagnose the issue, the following steps can be taken:

  1. Check the protocol version: Use the isisPduProtocolVersion variable to determine the protocol version reported in the PDU that triggered the trap.
  2. Identify the source of the issue: Analyze the isisPduFragment variable to extract the initial bytes of the PDU that triggered the trap, which may help identify the source of the confusion.
  3. Verify device configurations: Check the IS-IS protocol configurations on both devices to ensure they are running the same protocol version and compatible settings.
  4. Review network topology: Verify that the network topology is correctly configured and that there are no issues with network connectivity or routing.

Mitigation #

To mitigate the issue, the following steps can be taken:

  1. Upgrade or downgrade IS-IS protocol version: If the protocol version mismatch is the cause of the issue, upgrade or downgrade the IS-IS protocol version on the affected devices to match the version used by the other devices in the network.
  2. Configure compatible settings: Ensure that the IS-IS protocol settings are configured consistently across all devices in the network.
  3. Verify network topology: Re-verify the network topology to ensure that it is correctly configured and that there are no issues with network connectivity or routing.
  4. Monitor network performance: Continuously monitor network performance to detect any potential issues or degradation in network connectivity or routing.
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