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max-lsp-lifetime
Specifying the SPF Interval
Copyright © 2010, Juniper Networks, Inc.
Use to set the LSP rate at which locally generated LSPs are periodically transmitted.
The refresh interval determines the rate at which the router software periodically
transmits the route topology information that it originates. These transmissions refresh
the link-state information, reaffirming that the router is still up and that the link-state
information in the LSP is still valid.
You can set the interval rate in the range 1–65535 seconds; the default is 900 seconds.
LSPs must be periodically refreshed before their lifetimes expire. The refresh interval
must be less than the LSP lifetime specified by max-lsp-lifetime.
In the unlikely event that link stage database corruption is undetected, reducing the
refresh interval reduces the amount of time that the corruption can persist.
Increasing the interval reduces the link utilization caused by the flooding of refreshed
packets.
Example
host1(config-router)#lsp-refresh-interval 1000
Use the no version to restore the default value, 900 seconds.
See lsp-refresh-interval
Use to set the maximum time that LSPs persist without being refreshed.
You can select a maximum time in the range 1–65535 seconds.
The default value is 1200 seconds (20 minutes).
You might need to adjust the maximum LSP lifetime if you change the LSP refresh
interval with the lsp-refresh-interval command. The maximum LSP lifetime must be
greater than the LSP refresh interval.
Example
host1(config-router)#max-lsp-lifetime 1500
Use the no version to restore the default value, 1200 seconds.
See max-lsp-lifetime
You can configure how often the router performs the shortest-path-first (SPF) calculation.
IS-IS runs SPF calculations in response to any change in its link-state database. Because
SPF calculation is processor intensive, increasing the SPF interval reduces the processor
load of the router, but can slow down the rate of convergence.
Topology changes in a network cause all routers involved in the change to regenerate
their LSDB and flood new LSPs throughout the network. Therefore, a router that receives
a new LSP is likely to receive more LSPs in the following seconds. An immediate response
to a given change is going to miss the subsequent topology changes and spend CPU
Chapter 6: Configuring IS-IS
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