R0106-HP MSR Router Series Layer 3 - IP Routing Configuration Guide(V7)

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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:
Ste
p
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 flash
flooding.
flash-flood [ flood-count flooding-count |
max-timer-interval flooding-interval | [ level-1 |
level-2 ] ] *
By default, LSP flash
flooding is disabled.
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:
Ste
p
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.
lsp-fragments-extend [ level-1 |
level-1-2 | level-2 ]
By default, this feature is disabled.
4. Configure a virtual system
ID.
virtual-system virtual-system-id
By default, no virtual system ID is
configured.
Configure at least one virtual system to
generate extended LSP fragments.
Limiting LSP flooding
In NBMA networks such as ATM and FR, many P2P links exist. As shown in Figure 39, Routers A, B, C
and D run IS-IS. When Router A generates an LSP, it floods the LSP out of GigabitEthernet 2/1/1,
GigabitEthernet 2/1/2, and GigabitEthernet 2/1/3. After Router D receives the LSP from
GigabitEthernet 2/1/3, it floods it out of GigabitEthernet 2/1/1 and GigabitEthernet 2/1/2 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.