3Com Switch 7750 Configuration Guide

IS-IS Basic Configuration 343
Assigning an LSP
Maximum Aging Time
An LSP is given a maximum aging value when it is generated by the router. When
the LSP is sent to other routers, its maximum aging value goes down gradually. If
the router does not get the update for the LSP before the maximum aging value
reaches 0, the LSP will be deleted from the LSDB.
Configuring SPF
Parameters
Configuring the SPF interval
In IS-IS, a router needs to recalculate the shortest path when the LSDB changes.
Recalculating the shortest path upon change consumes enormous resources as
well as affects the operation efficiency of the router. With an SPF calculation
interval configured, when the LSDB changes, the SPF algorithm is not executed
until the SPF timer expires.
n
If you do not provide the level-1 or level-2 keyword, this command applies to
Level-1 and Level-2 by default.
Configuring SPF calculation durations
SPF calculation in IS-IS may occupy system resources for a long time if the routing
table contains a great number of entries (over 30,000). To avoid this, you can
configure SPF calculation durations.
Table 279 Assign an LSP refresh time
Operation Command Description
Enter system view system-view -
Enter IS-IS view isis [ tag ] Required
Assign an LSP refresh
time
timer lsp-refresh seconds Optional
By default, LSPs are refreshed
every 900 seconds, namely, 15
minutes.
Table 280 Assign an LSP maximum aging time
Operation Command Description
Enter system view system-view -
Enter IS-IS view isis [ tag ] Required
Assign an LSP maximum
aging time
timer lsp-max-age
seconds
Optional
By default, the LSP maximum aging time
is 1,200 seconds, namely, 20 minutes.
Table 281 Configure the SPF interval
Operation Command Description
Enter system view system-view -
Enter IS-IS view isis [ tag ] Required
Configure the SPF
interval
timer spf seconds [ level-1 |
level-2 ]
Optional
The default SPF interval is 10
seconds.
Table 282 Configure SPF calculation durations
Operation Command Description
Enter system view system-view -