The virtual-system command configures the virtual system ID for an IS-IS process.
The undo virtual system virtual-system-id command deletes the virtual system ID.
By default, there is no virtual system ID for an IS-IS process.
Usage Scenario
The virtual-system command is used to set a virtual system ID for an IS-IS process. If no virtual system ID exists, no extended LSPs are generated.
The virtual ID must be unique in the entire area. The virtual-system command is used together with the lsp-fragments-extend command. The configured virtual system ID takes effect only after LSP fragment extension is enabled. If LSP fragment extension is not enabled, virtual system IDs can be configured, but they do not take effect.Configuration Impact
After LSP fragment extension is configured, if information is lost because of LSP overflow, the system restarts the IS-IS process. After the IS-IS process is restarted, the system tries its best to load and package routing information. The excessive routing information that is beyond the forwarding capability of the system is placed into the LSPs of virtual systems. In addition, when a virtual system that is used to load routing information is deleted, the system automatically restarts the IS-IS process.