ISIS-MIB::isisRejectedAdjacency #
A notification sent when we receive a Hello PDU from an IS but do not establish an adjacency for some reason. The agent must throttle the generation of consecutive isisRejectedAdjacency 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
- isisPduFragment
Definitions #
- isisNotificationSysLevelIndex
- The system level for this notification.
- isisNotificationCircIfIndex
- The identifier of this circuit relevant to this notification.
- isisPduFragment
- Holds up to 64 initial bytes of a PDU that triggered the notification.
Here is a sample runbook for the SNMP trap ISIS-MIB::isisRejectedAdjacency:
Meaning #
The isisRejectedAdjacency trap is generated when the ISIS (Intermediate System to Intermediate System) protocol receives a Hello PDU from an Intermediate System (IS) but is unable to establish an adjacency for some reason. This trap indicates a problem with forming a neighbor relationship between ISIS routers, which is essential for exchanging routing information and maintaining network topology.
Impact #
Failure to establish an adjacency can lead to incomplete or inaccurate network topology information, causing routing issues, and potentially leading to network instability or outages. This can result in poor network performance, packet loss, and decreased network reliability.
Diagnosis #
To diagnose the issue, collect the following information:
- The system level for this notification (
isisNotificationSysLevelIndex) - The identifier of the circuit relevant to this notification (
isisNotificationCircIfIndex) - Up to 64 initial bytes of the PDU that triggered the notification (
isisPduFragment)
Analyze the collected information to identify the specific reason for the adjacency rejection. Possible causes include:
- Misconfigured ISIS router IDs or circuit IDs
- Incompatible ISIS protocol versions or implementations
- Network connectivity issues or hardware faults
- Resource constraints or overload on the affected routers
Mitigation #
To mitigate the issue, perform the following steps:
- Verify ISIS router configuration: Check the configuration of the affected routers to ensure that ISIS router IDs and circuit IDs are correctly configured.
- Check network connectivity: Verify that there are no network connectivity issues or hardware faults affecting the routers.
- Review ISIS protocol versions: Ensure that all routers are running compatible ISIS protocol versions and implementations.
- Monitor resource utilization: Check the resource utilization on the affected routers to identify any potential overload or constraint issues.
- Take corrective action: Based on the diagnosis, take corrective action to resolve the underlying issue, such as reconfiguring the routers, replacing faulty hardware, or upgrading software.