H3C Technologies H3C SecPath F1000-E - Manual (Page 538)

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Step Command Remarks
2. Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3. 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.
4. Specify the maximum length
of received LSPs.
lsp-length receive size 1497 bytes by default.
Enabling LSP flash flooding
Because 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.
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 ] ] *
Not enabled by
default.
Enabling 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 and specify the
working mode.
lsp-fragments-extend [ [ level-1 | level-1-2 |
level-2 ] | [ mode-1 | mode-2 ] ] *
Not enabled by default.
4. Configure a virtual system
ID.
virtual-system virtual-system-id 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 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 ATM, FR and NBMA networks, many P2P links exist. Figure 296 shows a fully meshed
network, where Routers A, B, C and D run IS-IS. When Router A generates an LSP, it floods the LSP out
Ethernet 1/1, Ethernet 1/2 and Ethernet 1/3. After receiving the LSP from Ethernet 1/3, Router D floods
it out 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. LSP flooding consumes extra bandwidth.