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Configure Multi-Topology IS-IS (MT IS-IS)
Configure IS-IS Graceful Restart
To enable IS-IS Graceful Restart globally, use the following command in ROUTER-ISIS mode. 
Additional, optional commands can be implemented to enable the Graceful Restart settings.
Step Task Command Syntax Command Mode
1 Enable Multi-Topology IS-IS for 
IPv6.
Enter the 
transition keyword to 
allow an IS-IS IPv6 user to continue 
to use single-topology mode while 
upgrading to multi-topology 
mode.After every router has been 
configured with the transition 
keyword, and all the routers are in 
MT IS-IS IPv6 mode users can 
remove the transition keyword on 
each router. 
multi-topology [transition] ROUTER ISIS AF IPV6
Note: When transition mode is not enabled, you will not have IPv6 connectivity between routers 
operating in single-topology mode and routers operating in multi-topology mode. 
2 Excluded this router from other 
router’s SPF calculations.
set-overload-bit
ROUTER ISIS AF IPV6
3 Set the minimum interval between 
SPF calculations.
spf-interval [level-l | level-2 | interval] 
[initial_wait_interval 
[second_wait_interval]]
ROUTER ISIS AF IPV6
This command is used for IPv6 route computation only when multi-topology is enabled. If using single-topology 
mode, use the spf-interval command in CONFIG ROUTER ISIS mode to apply to both IPv4 and IPv6 route 
computations.
4
Implement a wide metric-style 
globally.
To configure wide or wide transition 
metric style, the cost can be a 
between 0 and 16,777,215.
isis ipv6 metric metric-value [level-1 | 
level-2 | level-1-2]
ROUTER ISIS AF IPV6
Command Syntax Command Mode Purpose
graceful-restart ietf
ROUTER-ISIS Enable Graceful Restart on ISIS processes
graceful-restart interval minutes ROUTER-ISIS Configure the period of time during which the Graceful 
Restart attempt will be prevented. 
Range: 1-120 minutes
Default: 5 minutes