3Com Switch 8800 Family Configuration Guide

Configuring Integrated IS-IS 355
By default, LSP is refreshed every 900 seconds (15 minutes).
Setting Lifetime of LSP When a router generates the LSP of the system, it will fill in the maximum lifetime
of this LSP. When other routers receive this LSP, its life time will be reduced
continuously as the time goes. If updated LSP has not been received before the old
one times out, this LSP will be deleted from the LSDB.
Perform the following configuration in IS-IS view.
By default, LSP can live for 1200 seconds (20 minutes).
Setting Parameters
Related to SPF
Setting SPF calculation interval
When IS-IS LSDB changes, the router will compute the shortest path again.
However, the immediate calculation upon every change will occupy too many
resources and affect the efficiency of the router. In the case that SPF computing
interval is set, when LSDB changes, SPF algorithm will be run after the SPF interval
times out.
Perform the following configuration in IS-IS view.
If the level is not specified, it defaults to setting the SPF calculation interval of
Level-1.
By default, SPF calculation runs every 10 seconds.
Setting SPF calculation in slice
When there is a large number of routes in the routing table (over 150,000), SPF
calculation of IS-IS may occupy the system resources for a long time. To prevent
such a case, SPF calculation can be set to perform in slice.
Perform the following configuration in IS-IS view.
Tab le 336 Set LSP refreshment interval
Operation Command
Set LSP refreshment interval timer lsp-refresh seconds
Restore the default LSP refreshment interval undo timer lsp-refresh
Tab le 337 Set Lifetime of LSP
Operation Command
Set lifetime of LSP timer lsp-max-age seconds
Restore the default LSP lifetime undo timer lsp-max-age
Tab le 338 Set SPF calculation interval
Operation Command
Set SPF calculation interval timer spf second [ level-1 | level-2 ]
Restore default SPF calculation interval undo timer spf [ level-1 | level-2 ]