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Enabling LSP fragment extension
After LSP fragment extension is enabled for an IS-IS process, the MTUs of all the interfaces running the
IS-IS process must not be less than 512; otherwise, LSP fragment extension will not take effect.
At least one virtual system must be configured for the router to generate extended LSP fragments. An IS-IS
process allows 50 virtual systems.
To enable LSP fragment extension:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
3.
Enable LSP fragment
extension and specify the
working mode.
lsp-fragments-extend
[ [
level-1
|
level-1-2
|
level-2
] | [
mode-1
|
mode-2
] ] *
Not enabled by default.
4.
Configure a virtual system
ID.
virtual-system
virtual-system-id
Not configured by default.
Configuring SPF parameters
When the LSDB changes on a router, a route calculation starts. Frequent route calculations consume a lot
of system resources. You can set an appropriate interval for SPF calculations to improve efficiency.
To configure the SPF parameters:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
3.
Configure the SPF
calculation interval.
timer spf
maximum-interval
[
initial-interval
[
second-wait-interval
] ]
Optional.
The default SPF calculation
interval is 10 seconds.
Assigning a high priority to IS-IS routes
An IS-IS topology change causes network convergence. By assigning a high priority to specific IS-IS
routes, you can achieve faster network convergence.
To assign a high priority to IS-IS routes:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis
[
process-id
] [
vpn-instance
vpn-instance-name
]
N/A
