HP 4800G Series Configuration Manual page 534

Enabling LSP flash flooding
Since changed LSPs may trigger SPF recalculation, 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...
Enter system view
Enter IS-IS view
Enable LSP flash
flooding
Enabling LSP fragment extension
Follow these steps to enable LSP fragment extension:
To do...
Enter system view
Enter IS-IS view
Enable LSP fragment
extension and specify the
working mode
Configure a virtual system
ID
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 needs to be configured for the router to generate extended LSP
fragments. An IS-IS process allows 50 virtual systems at most.
Limiting LSP flooding
In well connected NBMA networks, many P2P links exist. The following figure shows a fully meshed
network, where Switchs A, B, C and D run IS-IS. When Switch A generates an LSP, it floods the LSP out
VLAN-interface 100, VLAN-interface 200 and VLAN-interface 300. After receiving the LSP from
VLAN-interface 100, Switch D floods it out VLAN-interface 200 and VLAN-interface 300 to Switch B and
Switch C, which however has received the LSP from Router A. In this case, LSP flooding consumes
extra bandwidth.
Use the command...
system-view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
flash-flood [ flood-count flooding-count |
max-timer-interval flooding-interval | [ level-1 |
level-2 ] ] *
Use the command...
system-view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
lsp-fragments-extend [ [ level-1 |
level-2 | level-1-2 ] | [ mode-1 |
mode-2 ] ] *
virtual-system virtual-system-id
1-27
Remarks
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––
Required
Not enabled by
default
Remarks
––
––
Required
Not enabled by default
Required
Not configured by default