H3C Technologies H3C S7500E Series Switches - Manual (Page 178)

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Configuring SPF Parameters
When the LSDB changes on a router, a route calculation starts. Frequent route calculations consume a
lot of system resources, while route calculations at a proper interval improve efficiency. You can set an
appropriate interval for SPF calculations as needed.
Follow these steps to configure the SPF parameters:
To do… Use the command... Remarks
Enter system view system-view ––
Enter IS-IS view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
––
Configure the SPF calculation
interval
timer spf maximum-interval [ initial-interval
[ second-wait-interval ] ]
Optional
The default SPF
calculation interval is 10
seconds.
Setting the LSDB Overload Bit
By setting the overload bit in sent LSPs, a router informs other routers of a failure that makes it
incapable of routing and forwarding packets.
When an IS-IS router cannot record the complete LSDB due to running out of memory or some other
reasons, it will calculate wrong routes. To make troubleshooting easier in this case, you can
temporarily isolate the router from the IS-IS network by setting the overload bit.
Follow these steps to set the LSDB overload bit:
To do… Use the command… Remarks
Enter system view system-view ––
Enter IS-IS view isis [ process-id ] [ vpn-instance vpn-instance-name ] ––
Set the overload bit
set-overload [ on-startup [ [ start-from-nbr system-id
[ timeout1 [ nbr-timeout ] ] ] | timeout2 ] [ allow { external |
interlevel } * ]
Required
Not set by default
Configuring IS-IS Authentication
To enhance the security of an IS-IS network, you can configure IS-IS authentication. IS-IS
authentication involves neighbor relationship authentication, area authentication and routing domain
authentication.
Configuration Prerequisites
Complete the following tasks before this configuration: