The isis circuit-level command sets a link type for an interface on a Level-1-2 router that runs IS-IS.
The undo isis circuit-level command restores the default setting.
By default, the link type of an interface on a Level-1-2 router that runs IS-IS is Level-1-2, and both Level-1 and Level-2 adjacencies can be established on the interface.
| Parameter | Description | Value |
|---|---|---|
| level-1 | Indicates the Level-1 link type. That is, you can set up only Level-1 adjacencies rather than Level-2 adjacencies on the interface. | - |
| level-1-2 | Indicates the Level-1-2 link type. That is, you can set up both Level-1 and Level-2 adjacencies on the interface. | - |
| level-2 | Indicates the Level-2 link type. That is, you can set up only Level-2 adjacencies on the interface. | - |
Ethernet interface view, Ethernet sub-interface view, Eth-Trunk interface view, Eth-Trunk sub-interface view, Tunnel interface view, Loopback interface view, Dialer interface view, VLANIF interface view, Virtual-Template interface view
Usage Scenario
When an adjacency is established between a Level-1-2 router and a remote device, the Level-1-2 router sends and receives both Level-1 and Level-2 Hello packets, wasting bandwidth and memory resources. To solve this problem, run the isis circuit-level command to set a specified link type for an interface.
Prerequisites
IS-IS has been enabled using the isis enable command in the interface view.
Configuration Impact
Network flapping may occur if the link type of an IS-IS interface is changed during network operation. Therefore, setting a link type for an IS-IS interface on the router when configuring IS-IS is recommended.
Precautions
The link type takes effect only when the system type of IS-IS is Level-1-2. Otherwise, the level defined by the is-level command is used as the link type.
# If the GigabitEthernet0/0/0 is connected to a non-backbone router in the same area. You can set this interface to Level-1, and prohibit the interface from sending and receiving Level-2 Hello packets.
<sysname> system-view
[sysname] interface GigabitEthernet 0/0/0 [sysname-GigabitEthernet0/0/0] isis enable [sysname-GigabitEthernet0/0/0] isis circuit-level level-1