show isis statistics

PDU type

Protocol data unit type:

• CSNP—Complete sequence number PDUs contain a complete list of all link-state PDUs in the IS-IS database. CSNPs are sent periodically on all links, and the receiving systems use the information in the CSNP to update and synchronize their link-state PDU databases. The designated router multicasts CSNPs on broadcast links in place of sending explicit acknowledgments for each link-state PDU.
• IIH—IS-IS hello packets are broadcast to discover the identity of neighboring IS-IS systems and to determine whether the neighbors are Level 1 or Level 2 intermediate systems.
• LSP—Link-state PDUs contain information about the state of adjacencies to neighboring IS-IS systems. Link-state PDUs are flooded periodically throughout an area.
• PSNP—Partial sequence number PDUs are sent multicast by a receiver when it detects that it is missing a link-state PDU; that is, when its link-state PDU database is out of date. The receiver sends a PSNP to the system that transmitted the CSNP, effectively requesting that the missing link-state PDU be transmitted. That router, in turn, forwards the missing link-state PDU to the requesting router.
• Unknown—The PDU type is unknown.

Received

Number of PDUs received since IS-IS started or since the statistics were set to zero.

Processed

Number of PDUs received less the number dropped.

Drops

Number of PDUs dropped.

Sent

Number of PDUs transmitted since IS-IS started or since the statistics were set to zero.

Rexmit

Number of PDUs retransmitted since IS-IS started or since the statistics were set to zero.

Total packets received/sent

Total number of PDUs received and transmitted since IS-IS started or since the statistics were set to zero.

SNP queue length

Number of CSPN and PSNP packets currently waiting in the queue for processing. This value is almost always 0.

LSP queue length

Number of link-state PDUs waiting in the queue for processing. This value is almost always 0.

SPF runs

Number of shortest-path-first (SPF) calculations that have been performed. If this number is incrementing rapidly, it indicates that the network is unstable.

Fragments rebuilt

Number of link-state link-state PDU fragments that the local system has computed.

LSP regenerations

Number of link-state PDUs that have been regenerated. A link state PDU is regenerated when it is nearing the end of its lifetime and it has not changed.

Purges initiated

Number of purges that the system initiated. A purge is initiated if the software decides that a link-state PDU must be removed from the network.