vlan-mapping modulo
Function
The vlan-mapping modulo command enables VLAN-to-instance mapping assignment based on a default algorithm.
The undo vlan-mapping modulo command restores the default mapping.
By default, all VLANs are mapped to CIST, namely, spanning tree instance 0.
Parameters
| Parameter | Description | Value |
|---|---|---|
| modulo | Specifies the value of a module. | The value is an integer ranging from 1 to 64. |
Usage Guidelines
Usage Scenario
MSTP divides a switching network into multiple regions, each of which has multiple spanning trees that are independent of each other. Each spanning tree is called an MSTI and each region is called an MST region.
- MST region name
- Mappings between MSTIs and VLANs
- MST region revision level
In the command, vlan-mapping modulo indicates that the formula (VLAN ID-1)%modulo+1 is used. In the formula, (VLAN ID-1)%modulo means the remainder of (VLAN ID-1) divided by the value of modulo. This formula is used to map a VLAN to the corresponding MSTI. The calculation result of the formula is ID of the mapping MSTI. For example, if the modulus is 16, the switch maps VLAN 1 to MSTI 1, VLAN 2 to MSTI 2 VLAN 16 to MSTI 16, VLAN 17 to MSTI 1, and so on.
Precautions
The instance instance-id vlan { vlan-id [ to vlan-id ] }&<1-10> command is recommended because VLAN-to-instance mapping assignments cannot meet actual mapping requirements.
VBST does not support regions. Therefore, this command does not take effect when the spanning tree protocol is VBST.