H3C Technologies H3C S7500E Series Switches - Manual (Page 176)

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To do… Use the command… Remarks
Enter system view system-view ––
Enter IS-IS view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
––
Enable LSP fragment
extension and specify the
working mode
lsp-fragments-extend [ [ level-1 | level-1-2 |
level-2 ] | [ mode-1 | mode-2 ] ] *
Required
Not enabled by default
Configure a virtual system ID virtual-system virtual-system-id
Required
Not configured by default
z 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.
z 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.