There are three global level and four interface level IS-IS timers. See IS-IS Timers for IS-IS timer details.
IS-IS Timers
| Timer | Description | Command |
|---|---|---|
| LSP Generation Interval | The minimum interval between the generation of LSPs, configured in the IS-IS configuration mode. | lsp-gen-interval |
| Maximum LSP Lifetime | The maximum time the LSPs persist without being refreshed. | max-lsp-lifetime |
| SFP Interval | The minimum amount of time between Shortest Path First (SFP) processing on an IS-IS instance. When a topology change occurs the SPF calculation is run. The SPF calculation is not run when external routes change. The SPF calculation is CPU intensive. For a network with a large area and frequent topology changes you may want to increase the minimum time between SPF calculations. Increasing the SPF interval reduces the processor load, but potentially slows the rate of convergence. |
sfp-interval |
| Complete Sequence Number PDU Interval | The IS-IS Complete Sequence Number PDU (CSNP) interval for the interface. Designated Routers (DRs) send out CSNP packets on the interface to maintain database synchronization. | isis csnp-interval |
| Hello Interval | The IS-IS Hello PDU interval for the interface. The advertised holdtime in the hello packet is set to three times the hello interval seconds. Topological changes are detected faster with a smaller hello interval, but there is more routing traffic. The number of hello packets a neighbor must miss before the intermediate system declares the adjacency down on the interface is the holdtime multiplier which can be changed using the isis hello-multiplier command. |
isis hello-interval |
| LSP transmission interval | The minimum interval between the transmission of Link-State Packets (LSP)s on the interface. | isis lsp-throttle |
| LSP retransmission interval | The minimum interval between the retransmission of the same LSP. The retransmit interval should be greater than the expected round-trip delay between any two intermediate systems on the attached network. Retransmissions occur when LSPs are dropped. Higher retransmission values have little effect on reconvergence. The more neighbors intermediate systems have, and the more paths over which LSPs can be flooded, the higher this value can be made. | isis retransmission-interval |
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