143
Step Command
Remarks
4.
Specify the maximum length
of received LSPs.
lsp-length receive
size
By default, the maximum length
of received LSPs is 1497 bytes.
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 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 128. Otherwise, LSP fragment extension does not take
effect.
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.
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 38
, Routers A, B, C
and D run IS-IS. When Router A generates an LSP, it floods the LSP out of Ethernet 1/1, Ethernet 1/2 and
Ethernet 1/3. After Router D receives the LSP from Ethernet 1/3, it floods it out of Ethernet 1/1 and
Ethernet 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.
