MST - VLAN Assignment to IST

## Operating Environment
OS : Windows 11 Home 23H2
VM : VMware® Workstation 17 Pro 17.5.2
Software：CML 2.7.2
Hardware：N/A

## Network Topology
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/1cbbb258-ff4d-65ca-c046-0ac6ad3de63e.png)

## Basic Configuration
### SW1
MGMT IP address : interface VLAN 10 - 192.168.1.1/24
G0/0 : access port, VLAN 10
G0/1 : access port, VLAN 20
G0/2 : access port, VLAN 10
### SW2
MGMT IP address : interface VLAN 10 - 192.168.1.2/24
G0/0 : access port, VLAN 10
G0/1 : access port, VLAN 20
G0/2 : access port, VLAN 10
### PC1
IP address : 192.168.1.100
### PC1
IP address : 192.168.1.200
### Ping test OK
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/84843593-a87c-24e6-29d1-76e5fb1ba0e7.png)
### Confirm Configuration
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/5907c571-1fbc-595f-ab10-fd6e680e142b.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/5366f4e3-9e7d-2b60-c0cd-d5e84b430e59.png)

## MST Configuration
### SW1
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/6a826a6a-61bb-f6c2-cb87-79a4eabb6090.png)

### SW2
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/8845ebd9-e75b-53c6-c77a-7333989fe72c.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/fc30a0de-75d0-3d03-0cc3-738f10cb82c9.png)

## Problem - VLAN 10 Blocked
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/9986b060-e1a2-f76c-2f91-6d0558870d0c.png)
![Screenshot 2024-11-21 105019.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/f08b0a61-f3fe-1c3d-ab9c-97e4aafa92d2.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/52f6fa15-b658-6066-7b4d-19fc5ea0d931.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/7ae8ddb8-4886-e13c-a7ca-bcc7098904ae.png)

:::note warn
Since IST runs on all MST ports, independent of VLAN configuration, it results in a redundant link between SW1 and SW2, which in turn blocks SW1's G0/2 port
:::

## Solution

### 1.Allow the VLANs assigned to IST on all interswitch (trunk) links
#### SW1 
G0/2
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/37c3de40-d141-6470-9964-c8546c774ff2.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/613983e9-09e7-1e6c-1507-786924eff1bc.png)
#### SW2
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/6e799f95-a30a-e143-87bc-a9894df83fa8.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/509c0632-8f22-e9f3-fac6-1b298471cf2e.png)
#### Ping test OK (PC2)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/06075358-b161-786e-1ac1-a2955af97c06.png)

### 2.Move VLAN 10 to an MSTI instance which is not IST. 
#### SW1 
![Screenshot 2024-11-21 112040.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/b98772a1-c462-e3d5-1978-1e19fc291192.png)
#### SW2
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/35554cf0-4667-c869-cb9c-09690ecbc181.png)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/1bdadfff-788f-5354-8c97-eecf31a83a9b.png)
#### Ping test OK (PC2)
![image.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/3923257/95c65229-6051-8a26-c657-4c372d4490a1.png)