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NOTE: When you do not enable Transition mode, you do not have IPv6 connectivity between routers operating in
single-topology mode and routers operating in multi-topology mode.
2. Exclude this router from other router’s SPF calculations.
ROUTER ISIS AF IPV6 mode
set-overload-bit
3. Set the minimum interval between SPF calculations.
ROUTER ISIS AF IPV6 mode
spf-interval [level-l | level-2 | interval] [initial_wait_interval
[second_wait_interval]]
Use this command for IPv6 route computation only when you enable multi-topology. If using single-topology mode, to apply
to both IPv4 and IPv6 route computations, use the spf-interval command in CONFIG ROUTER ISIS mode.
4. Implement a wide metric-style globally.
ROUTER ISIS AF IPV6 mode
isis ipv6 metric metric-value [level-1 | level-2 | level-1-2]
To configure wide or wide transition metric style, the cost can be between 0 and 16,777,215.
Configuring IS-IS Graceful Restart
To enable IS-IS graceful restart globally, use the following commands. Additionally, you can implement optional commands to
enable the graceful restart settings.
● Enable graceful restart on ISIS processes.
ROUTER-ISIS mode
graceful-restart ietf
● Configure the time during which the graceful restart attempt is prevented.
ROUTER-ISIS mode
graceful-restart interval minutes
The range is from 1 to 120 minutes.
The default is 5 minutes.
● Enable the graceful restart maximum wait time before a restarting peer comes up.
ROUTER-ISIS mode
graceful-restart restart-wait seconds
When implementing this command, be sure to set the t3 timer to adjacency on the restarting router.
The range is from 1 to 120 minutes.
The default is 30 seconds.
● Configure the time that the graceful restart timer T1 defines for a restarting router to use for each interface, as an interval
before regenerating Restart Request (an IIH with RR bit set in Restart TLV) after waiting for an acknowledgement.
ROUTER-ISIS mode
graceful-restart t1 {interval seconds | retry-times value}
○ interval: wait time (the range is from 5 to 120. The default is 5.)
○ retry-times: number of times an unacknowledged restart request is sent before the restarting router gives up the
graceful restart engagement with the neighbor. (The range is from 1 to 10 attempts. The default is 1.)
● Configure the time for the graceful restart timer T2 that a restarting router uses as the wait time for each database to
synchronize.
ROUTER-ISIS mode
graceful-restart t2 {level-1 | level-2} seconds
○ level-1, level-2: identifies the database instance type to which the wait interval applies.
The range is from 5 to 120 seconds.
The default is 30 seconds.
Intermediate System to Intermediate System
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