H3C Technologies H3C S10500 Series Switches - Manual (Page 174)

159
If the IS-IS routers have different interface MTUs, H3C recommends configuring the maximum size of
generated LSP packets to be smaller than the smallest interface MTU in this area. If they are not, the
routers must dynamically adjust the LSP packet size to fit the smallest interface MTU, which takes time and
affects other services.
Follow these steps to specify LSP lengths:
To do… Use the command… Remarks
Enter system view system-view —
Enter IS-IS view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
—
Specify the maximum length of
generated Level-1 LSPs or Level-2
LSPs
lsp-length originate size [ level-1 | level-2 ] 1497 bytes by default
Specify the maximum length of
received LSPs
lsp-length receive size 1497 bytes by default
Enabling LSP flash flooding
Changed LSPs may trigger SPF recalculation, so you can enable LSP flash flooding to advertise the
changed LSPs before the router recalculates routes. Doing so can speed up network convergence.
Follow these steps to enable LSP flash flooding:
To do… Use the command… Remarks
Enter system view system-view —
Enter IS-IS view isis [ process-id ] [ vpn-instance vpn-instance-name ] —
Enable LSP flash flooding
flash-flood [ flood-count flooding-count |
max-timer-interval flooding-interval | [ level-1 |
level-2 ] ] *
Required
Not enabled by
default
Enabling LSP fragment extension
Follow these steps to enable LSP fragment extension:
To do… Use the command… Remarks
Enter system view system-view —
Enter IS-IS view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
—
Enable LSP fragment extension
and specify the working mode lsp-fragments-extend [ [ level-1 | level-1-2 |
level-2 ] | [ mode-1 | mode-2 ] ] * Required
Not enabled by default
Configure a virtual system ID virtual-system virtual-system-id
Required
Not configured by default
NOTE:
•
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.