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IS-IS Purge Originator Identification Overview

When the IS-IS protocol purges entries from IS-IS link-state database, there is no way to identify the origin of the purge. If there is a need to investigate the cause of the purge, it is difficult to determine the Intermediate system (IS) that initiated the purge. RFC 6232, Purge Originator Identification TLV for IS-IS defines a type, length, and value (TLV) that can be added to the purges, to record the system ID of the IS that had initiated the purge. If an IS generates a purge, this TLV is included in the purge, which also has the system ID of the IS. If an IS receives a purge, the Link State Protocol Data Unit (LSP) flooding does not change the LSP contents, and the TLV is propagated with the purge itself. If an IS receives a purge that does not include this TLV, it adds this TLV with both its own system ID and the system ID of the IS from which it received the purge. This allows the IS that receives this purge to log the system ID of the originator, or the upstream source of the purge. This makes it easier to locate the origin of the purge and its cause. This TLV is also helpful in lab environments.

Change History Table

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Release
Description
16.1
Configuration of Purge Origination Identification is available to identify the origin of an IS-IS purge.