The isis circuit-level command sets the link type of an interface on a Level-1-2 router.
The undo isis circuit-level command restores the default link type of an interface on a Level-1-2 router.
By default, the link type of an interface on a Level-1-2 router is Level-1-2, and both Level-1 and Level-2 neighbor relationships can be established on the interface.
| Parameter | Description | Value |
|---|---|---|
| level-1 | Specifies the Level-1 link type. That is, only Level-1 neighbor relationship can be established on the interface. | - |
| level-1-2 | Specifies the Level-2 link type. That is, both Level-1 and Level-2 neighbor relationships can be established on the interface. | - |
| level-2 | Specifies the Level-2 link type. That is, only Level-2 neighbor relationship can be established on the interface. | - |
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.
Precautions
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 switch when configuring IS-IS is recommended.
The configuration of the isis circuit-level command takes effect only when the IS-IS system type is Level-1-2. Otherwise, the level configured using the is-level command is used as the link type.
# If VLANIF100 is connected to a non-backbone router in the same area, set this interface to Level-1, and prohibit the interface from sending and receiving Level-2 Hello packets.
<HUAWEI> system-view [HUAWEI] isis [HUAWEI-isis-1] network-entity 01.0000.0000.0001.00 [HUAWEI-isis-1] quit [HUAWEI] interface vlanif 100 [HUAWEI-Vlanif100] isis enable 1 [HUAWEI-Vlanif100] isis circuit-level level-1
# If GE0/0/1 is connected to a non-backbone router in the same area, set this interface to Level-1, and prohibit the interface from sending and receiving Level-2 Hello packets.
<HUAWEI> system-view [HUAWEI] isis [HUAWEI-isis-1] network-entity 01.0000.0000.0001.00 [HUAWEI-isis-1] quit [HUAWEI] interface gigabitethernet 0/0/1 [HUAWEI-GigabitEthernet0/0/1] undo portswitch [HUAWEI-GigabitEthernet0/0/1] isis enable 1 [HUAWEI-GigabitEthernet0/0/1] isis circuit-level level-1