Configuring summary addresses

Enter the configure terminal command to access global configuration mode.
```
device# configure terminal
```
Enter the router isis command to enter IS-IS router configuration mode and enable IS-IS on the device.
```
device(config)# router isis
```
Enter the address-family ipv4 unicast command to enable ISIS address-family IPv4 unicast configuration mode.
```
device(config-isis-router)# address-family ipv4 unicast
```
Enter the summary-address command with the level-1 and level-2 parameters, specifying an IPv4 address and network mask to configure a summary address and network mask for Level 1 and Level 2 routes.
```
device(config-router-isis-ipv4u)# summary-address 10.1.0.0 255.255.0.0 level-1 level-2
```

Example

The following example configures a summary address of 10.1.0.0 with a mask of 255.255.0.0 for Level 1 and Level 2 routes.

device# configure terminal
device(config)# router isis
device(config-isis-router)# address-family ipv4 unicast
device(config-router-isis-ipv4u)# summary-address 10.1.0.0 255.255.0.0 level-1 level-2