HP HPE FlexNetwork 7500 series Configuration Manual page 166

Step
4. Specify the maximum length
of received LSPs.
Enabling LSP flash flooding
Changed LSPs can trigger SPF recalculation. To advertise the changed LSPs before the router
recalculates routes for faster network convergence, enable LSP flash flooding.
To enable LSP flash flooding:
Step
1. Enter system view.
2. Enter IS-IS view.
3. Enable LSP flash flooding.
Enabling LSP fragment extension
Perform this task to enable IS-IS fragment extension for an IS-IS process. The MTUs of all interfaces
running the IS-IS process must not be less than 512. Otherwise, LSP fragment extension does not
take effect.
To enable LSP fragment extension:
Step
1. Enter system view.
2. Enter IS-IS view.
3. Enable LSP fragment
extension.
4. Configure a virtual
system ID.
Limiting LSP flooding
In some networks, many P2P links exist. As shown in
When Router A generates an LSP, it floods the LSP out of GigabitEthernet 1/0/1, GigabitEthernet
1/0/2, and GigabitEthernet 1/0/3. After Router D receives the LSP from GigabitEthernet 1/0/3, it
floods it out of GigabitEthernet 1/0/2 and GigabitEthernet 1/0/1 to Router B and Router C. However,
Router B and Router C have already received the LSP from Router A. Repeated LSP flooding
consumes extra bandwidth.
Command
lsp-length receive size
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 ] ] *
Command
system-view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
lsp-fragments-extend [ level-1 |
level-1-2 | level-2 ]
virtual-system virtual-system-id
154
Remarks
By default, the maximum
length of received LSPs is
1497 bytes.
Remarks
N/A
N/A
By default, LSP flash
flooding is disabled.
Remarks
N/A
N/A
By default, this feature is disabled.
By default, no virtual system ID is
configured.
Configure a minimum of one virtual
system to generate extended LSP
fragments.
Figure 41, Routers A, B, C and D run IS-IS.