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play_arrow Overview
- Spanning Tree Protocol Overview
play_arrow Spanning-Tree Instances and Interfaces
- Spanning Tree Instances and Interfaces
play_arrow Configuring Spanning-Tree Protocols
play_arrow BPDU Protection for Spanning-Tree Protocols
- BPDU Protection for Spanning-Tree Protocols
play_arrow Loop Protection for Spanning-Tree Protocols
- Loop Protection for Spanning-Tree Protocols
play_arrow Root Protection for VPLS Multihome Environments
- Root Protection for VPLS Multihome Environments
play_arrow Monitoring and Troubleshooting
- Monitoring and Troubleshooting Spanning Tree Protocols
play_arrow Configuration Statements and Operational Commands
- Junos CLI Reference Overview

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English

Configuring MSTP

date_range 09-Dec-23

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Multiple Spanning Tree Protocol (MSTP) maps multiple VLANs into a spanning tree instance, with each instance having a spanning tree topology independent of other spanning tree instances.

Understanding MSTP

Ethernet networks are susceptible to broadcast storms if loops are introduced. However, an Ethernet network needs to include loops because they provide redundant paths in case of a link failure. Spanning-tree protocols address both of these issues because they provide link redundancy while simultaneously preventing undesirable loops.

Spanning-tree protocols intelligently avoid loops in a network by creating a tree topology (spanning tree) of the entire bridged network with only one available path between the tree root and a leaf. All other paths are forced into a standby state. The tree root is a switch within the network elected by the STA (spanning-tree algorithm) to use when computing the best path between bridges throughout the network and the root bridge. Frames travel through the network to their destination– a leaf. A tree branch is a network segment, or link, between bridges. Switches that forward frames through an STP spanning-tree are called designated bridges.

Juniper Networks devices provide Layer 2 loop prevention through Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), Multiple Spanning Tree Protocol (MSTP), and VLAN Spanning Tree Protocol (VSTP). This topic explains MSTP.

Note:

If you are using Junos OS for EX Series and QFX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style, you can force the original IEEE 802.1D Spanning Tree Protocol (STP) version to run in place of RSTP or VSTP by setting force-version.

This topic describes:

Benefits of MSTP
MSTP Maps Multiple VLANs
Configuring MSTP Regions
Selecting a Spanning Tree Protocol

Benefits of MSTP

MSTP has the following benefits:

Multiple Spanning Tree Protocol works with most VLANs.
MSTP supports multiple instances on a single physical interface.
On MX Series and ACX Series routers, you can configure RSTP, MSTP, and VSTP instance interfaces as edge ports.

MSTP Maps Multiple VLANs

MSTP is an extension of RSTP that maps multiple independent spanning-tree instances onto one physical topology. Each spanning-tree instance (STI) includes one or more VLANs. Unlike in STP and RSTP configurations, a port might belong to multiple VLANs and be dynamically blocked in one spanning-tree instance, but forwarding in another. This behavior significantly improves network resource utilization by load-balancing across the network and maintaining switch CPU loads at moderate levels. MSTP also leverages the fast reconvergence time of RSTP when a network, switch, or port failure occurs within a spanning-tree instance.

MSTP creates a common and internal spanning tree (CIST) to interconnect and manage all MSTP regions and even individual devices that run RSTP or STP, which are recognized as distinct spanning-tree regions by MSTP. The CIST views each MSTP region as a virtual bridge, regardless of the actual number of devices participating in the MSTP region, and enables multiple spanning-tree instances (MSTIs) to link to other regions. The CIST is a single topology that connects all switches (STP, RSTP, and MSTP devices) through an active topology, ensuring connectivity between LANs and devices within a bridged network. This functionality provided by MSTP enables you to better utilize network resources while remaining backward-compatible with older network devices.

Configuring MSTP Regions

When enabling MSTP, you define one or more MSTP regions. An MSTP region defines a logical domain where multiple spanning-tree instances (MSTIs) can be administered independently of MSTIs in other regions, setting the boundary for bridge protocol data units (BPDUs) sent by one MSTI. An MSTP region is a group of switches that is defined by three parameters:

Region name—User-defined alphanumeric name for the region.
Revision level—User-defined value that identifies the region.
Mapping table—Numerical digest of VLAN-to-instance mappings.

An MSTP region can support up to 64 MSTIs,, and each MSTI can support from 1 to 4094 VLANs. When you define a region, MSTP automatically creates an internal spanning-tree instance (IST instance 0) that provides the root switch for the region and includes all currently configured VLANs that are not specifically assigned to a user-defined MSTI. An MSTI includes all static VLANs that you specifically add to it. The switch places any dynamically created VLANs in the IST instance by default, unless you explicitly map them to another MSTI. Once you assign a VLAN to a user-defined MSTI, the switch removes the VLAN from the IST instance.

Selecting a Spanning Tree Protocol

The default factory configuration is RSTP, a faster version of STP. To determine which spanning-tree protocol is best for your situation, see Table 1 below.

Table 1: Selecting a Spanning Tree Protocol
Protocol	Advantages	Disadvantages
RSTP	Rapid Spanning Tree Protocol is the default switch configuration and is recommended for most network configurations because it converges more quickly than STP after a failure. Voice and video work better with RSTP than they do with STP. RSTP is backward compatible with STP; therefore, switches do not all have to run RSTP.	RSTP does not work with 802.1D 1998 bridges.
STP	Spanning Tree Protocol works with 802.1D 1998 bridges. RSTP is backward compatible with STP; therefore, switches do not all have to run STP.	STP is slower than RSTP. STP is not recommended for multiple VLAN networks because it is not VLAN-aware—as a result, all VLANs within a LAN share the same spanning-tree. This limits the number of forwarding paths for data traffic. If you are using Junos OS for EX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style, you can force the original IEEE 802.1D Spanning Tree Protocol (STP) version to run in place of RSTP or VSTP by setting force-version. However, the CLI does not include `[edit protocols stp].`
MSTP	Multiple Spanning Tree Protocol works with most VLANs. RSTP and STP are recognized as distinct spanning-tree regions by MSTP.	Some protocols require compatibility that is not provided by MSTP. In this case, use VSTP. MSTP uses more CPU than RSTP and does not converge as fast as RSTP.
VSTP	VLAN Spanning Tree Protocol works with VLANs that require device compatibility. VSTP and RSTP are the only spanning-tree protocols that can be configured concurrently on a switch.	With VSTP there can be only STP instance per VLAN, whereas MSTP lets you combine multiple VLANs in one instance. VSTP supports a limited number of ports compared to RSTP. VSTP uses more CPU than RSTP and does not converge as fast as RSTP. Having a large number of VSTP and RSTP instances can cause continuous changes in the topology. Ensure to check the scale limits before configuring large number of VSTP instances.

Configuring MSTP

You can configure the Multiple Spanning Tree Protocol (MSTP) under the [edit protocols] hierarchy.

You can configure the Multiple Spanning Tree Protocol (MSTP) under the following hierarchy levels:

[edit logical-systems logical-system-name protocols]
[edit logical-systems logical-system-name routing-instances routing-instance-name protocols]
[edit protocols]
[edit routing-instances routing-instance-name protocols]

The routing instance type can be either virtual-switch or layer2-control.

To configure the Multiple Spanning Tree Protocol:

Enable MSTP as the version of spanning-tree protocol to be configured:
```
[edit]
user@switch@ edit ... protocols mstp 
```
Configure the interfaces that participate in the MSTP instance for all interfaces at one time, or for configured interface ranges, or for specific interfaces individually:
- Enable MSTP on all the interfaces at one time, for switches that support this option (most switches):
  [edit ... protocols mstp] user@switch# set interface all
  Note:
  You cannot disable MSTP on all the interfaces with one command. See the configuration steps for configuring MSTP on specific interfaces later in this topic for how to disable MSTP on interfaces individually.
  For QFX5100 switches, which do not support the interface all option, you must configure interface ranges for the applicable interfaces on which you want to enable MSTP, and then issue the set protocols mstp interface name command for each name that you have configured as an interface range (described next).
- Enable MSTP on a range of interfaces, for switches such as QFX5100 switches that do not support the interface all option:
  1. Configure interface ranges using the interface-range statement at the [edit interfaces] hierarchy level for the applicable interfaces on which you want to enable MSTP:
    [edit interfaces] user@switch# set interface-range interface-range-name member-range interface-name1 to interface-name2
  2. Enable MSTP for each configured interface range interface-range-name at the [edit ... protocols mstp] hierarchy level:
    [edit ... protocols mstp] user@switch# set interface interface-range-name
- Configure a specific interface individually to enable MSTP and various MSTP options on that interface, or to disable MSTP on that interface:
  1. Enable MSTP on the specified interface:
    [edit ... protocols mstp] user@switch# edit interface interface-name
  2. Configure the interface priority:
    [edit ... protocols mstp interface interface-name] user@switch# set priority interface-priority
  3. (Optional) By default, the interface link cost is determined by the link speed. You can configure the interface link cost to control which bridge is the designated bridge and which port is the designated port:
    [edit ... protocols mstp interface interface-name] user@switch# set cost interface-link-cost
  4. Configure the interface link mode to identify point-to-point links:
    [edit ... protocols mstp interface interface-name] user@switch# set mode (p2p | shared)
    Specify p2p if the link is point to point. Specify shared if the link is a shared media.
  5. (Optional) Configure the interface as an edge port:
    [edit ... protocols mstp interface interface-name] user@switch# set edge
    Edge ports do not expect to receive bridge protocol data unit (BPDU) packets. If a BPDU packet is received for an edge port, the port becomes a nonedge port
  6. (Optional) Disable MSTP on a specific interface:
    [edit protocols mstp interface interface-name] user@switch# set disable
You can also enable BPDU root protection for all spanning-tree protocol instances on the interface. BPDU root protect ensures the port is the spanning-tree designated port. If the port receives superior BPDU packets, root protect moves this port to a root-prevented spanning-tree state. For configuration details, see Checking the Status of Spanning-Tree Instance Interfaces.
Configure the bridge priority.
```
[edit ... protocols mstp]
user@switch# set bridge-priority bridge-priority
```
For more information, see Understanding Bridge Priority for Election of Root Bridge and Designated Bridge.
Configure hello BPDU timers.
1. Configure the maximum expected arrival time of hello BPDUs:
  [edit ... protocols mstp] user@switch# set max-age seconds
2. Configure the time interval at which the root bridge transmits configuration BPDUs:
  [edit ... protocols mstp] user@switch# set hello-time seconds
(Optional) By default, the bridge port remains in the listening and learning states for 15 seconds before transitioning to the forwarding state. You can specify a delay from 4 through 20 seconds instead:
```
[edit ... protocols mstp]
user@switch# set forward-delay seconds
```
Configure MSTP-specific options.
1. Configure the MSTP region configuration name:
  [edit ... protocols mstp] user@switch# set configuration-name configuration-name
2. Configure the MSTP revision level:
  [edit ... protocols mstp] user@switch# set revision-level revision-level
3. Configure the maximum number of hops that can be forwarded in the MSTP region:
  [edit ... protocols mstp] user@switch# set max-hops hops

Configuring MSTP Instances on a Physical Interface

You can configure a Multiple Spanning Tree Instance (MSTI) under the following hierarchy levels:

[edit logical-systems logical-system-name protocols mstp]
[edit logical-systems logical-system-name routing-instances routing-instance-name protocols mstp]
[edit protocols mstp]
[edit routing-instances routing-instance-name protocols mstp]

The routing instance type can be either virtual-switch or layer2-control.

Before you begin, configure Multiple Spanning-Tree Protocol. For configuration details, see Configuring Multiple Spanning Tree Protocol.

Enable configuration of an MST instance:
```
[edit]
user@host# edit ... protocols mstp msti msti-id
```
The msti-id value must be from 1 through 64.
Configure the interfaces that participate in the MST instance.
1. Enable configuration of the interface:
  [edit ... protocols mstp msti msti-id] user@host# edit interface interface-name
2. Configure the interface priority:
  [edit ... protocols mstp msti msti-id interface interface-name] user@host# set priority interface-priority
3. (Optional) By default, the interface link cost is determined by the link speed. You can configure the interface link cost to control which bridge is the designated bridge and which port is the designated port:
  [edit ... protocols mstp msti msti-id interface interface-name] user@host# set cost interface-link-cost
4. (Optional) Configure the interface as an edge port:
  [edit ... protocols mstp msti msti-id interface interface-name] user@host# set edge
  Edge ports do not expect to receive bridge protocol data unit (BPDU) packets. If a BPDU packet is received for an edge port, the port becomes a non-edge port
Configure the bridge priority:
```
[edit ... protocols mstp msti msti-id]
user@host# set bridge-priority bridge-priority
```
For more information, see Understanding Bridge Priority for Election of Root Bridge and Designated Bridge.
(Optional) An MSTI can map to a range of VLANs just as a logical port can map to a range of VLANs. The MSTP VLAN specifies the VLAN or VLAN range to which this MSTI is mapped. The vlan-id is configured under the logical interface. Configure the VLAN or VLAN range of the MSTI instance:
```
[edit]
user@host# set vlan (vlan-id | vlan-id-range)
```

Verify the MST interface configuration.

[edit]
protocols {
    mstp {
        ...basic-mstp-configuration...
        
        msti msti-id { # Instance identifier 1 – 64.
            bridge-priority priority; 
            vlan vlan-id; # Optional
            interface interface-name {
                cost cost;
                edge;
                priority interface-priority;
            }
        }
    }
}

Example: Configuring Network Regions for VLANs with MSTP

Note:

This example uses Junos OS for EX Series and QFX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style. The example also describes the configuration statement differences that can be substituted in the same configuration on EX Series switches that do not support ELS.

Multiple Spanning Tree Protocol (MSTP) is used to create a loop-free topology in networks using multiple spanning-tree regions in which each region contains multiple spanning-tree instances (MSTIs). MSTIs provide different paths for different VLANs. This functionality facilitates better load sharing across redundant links.

Up to 64 MSTIs can be created for an EX Series switch, and each MSTI can support up to 4094 VLANs.

This example describes how to configure MSTP on four EX Series switches:

Requirements
Overview and Topology
Configuring MSTP on Switch 1
Configuring MSTP on Switch 2
Configuring MSTP on Switch 3
Configuring MSTP on Switch 4
Verification

Requirements

This example uses the following software and hardware components:

Junos OS Release 13.2X50-D10 or later for EX Series or QFX Series switches
Four QFX Series switches

Before you configure the switches for MSTP, be sure you have:

Installed and connected the four switches. See the hardware documentation for your switch.
Performed the initial software configuration on all switches. See Connecting and Configuring an EX Series Switch (CLI Procedure) or Connecting and Configuring an EX Series Switch (J-Web Procedure).

Overview and Topology

When the number of VLANs grows in a network, MSTP provides an efficient way of creating a loop-free topology by using MSTIs. Each MSTI in the spanning-tree domain maintains its own tree. Each tree can be mapped to different links, utilizing bandwidth that would be unavailable to a single tree. MSTIs reduce the demand on system resources.

Topology

Figure 1: Network Topology for MSTP

The interfaces shown in Figure 1 will be configured for MSTP.

Table 2: Components of the Topology for Configuring MSTP on EX Series Switches
Property	Settings
Switch 1	The following interfaces on Switch 1 are connected in this way: `xe-0/0/12:0` is connected to Switch 2 `xe-0/0/9:0` is connected to Switch 4 `xe-0/0/11:0` is connected to Switch 3
Switch 2	The following interfaces on Switch 2 are connected in this way: `xe-0/0/9:0` is connected to Switch 1 `et-0/0/3` is connected to Switch 3
Switch 3	The following interfaces on Switch 3 are connected in this way: `xe-0/0/11:0` is connected to Switch 1 `et-0/0/6` is connected to Switch 2 `xe-0/0/21:0` is connected to Switch 4
Switch 4	The following interfaces on Switch 4 are connected in this way: `xe-0/0/21:0` is connected to Switch 1 `xe-0/0/12:0` is connected to Switch 3
VLAN names and tag IDs	`voice-vlan`, tag `10` `employee-vlan`, tag `20` `guest-vlan`, tag `30` `camera-vlan`, tag `40`
MSTIs	`1` `2`
MSTI region	`region1`

The topology in Figure 1 shows a common and internal spanning tree (CIST). The CIST is a single spanning tree connecting all devices in the network. The switch with the lowest bridge priority is elected as the root bridge of the CIST. You can control the election of the root bridge by configuring the bridge priority. Switch 3 is the root bridge of the CIST.

The ports in an MSTP topology have specific roles:

The root port is responsible for forwarding data to the root bridge.
The alternate port is a standby port for the root port. When a root port goes down, the alternate port becomes the active root port.
The designated port forwards data to the downstream network segment or device.
The backup port becomes the active designated port and starts forwarding data when the designated port goes down.

In this example, one MSTP region contains Switch 1, Switch 2, Switch 3, and Switch 4. Within the region, four VLANs are created:

voice-vlan supports voice traffic and has the VLAN tag identifier of 10.
employee-vlan supports data traffic and has the VLAN tag identifier of 20.
guest-vlan supports guest VLAN traffic (for supplicants that fail authentication) and has the VLAN tag identifier of 30.
camera-vlan supports video traffic and has the VLAN tag identifier of 40.

The VLANs are associated with specific interfaces on each of the four switches. Two MSTIs, 1 and 2, are then associated with the VLAN tag identifiers, and some MSTP parameters, such as cost, are configured on each switch.

Configuring MSTP on Switch 1

CLI Quick Configuration

To quickly configure interfaces and MSTP on Switch 1, for ELS switches, copy the following commands and paste them into the switch terminal window:

content_copy zoom_out_map
[edit]
set vlans voice-vlan description “Voice VLAN”
set vlans voice-vlan vlan-id 10
set vlans employee-vlan description “Employee VLAN”
set vlans employee-vlan vlan-id 20
set vlans guest-vlan description “Guest VLAN”
set vlans guest-vlan vlan-id 30
set vlans camera-vlan description “Camera VLAN”
set vlans camera-vlan vlan-id 40
set interfaces xe-0/0/9:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/12:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/11:0 unit 0 family ethernet-switching vlan members [10 20 30 40] 
set interfaces xe-0/0/9:0 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/0/12:0 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/0/11:0 unit 0 family ethernet-switching interface-mode trunk
set protocols mstp configuration-name region1
set protocols mstp bridge-priority 16k
set protocols mstp interface xe-0/0/9:0 cost 1000
set protocols mstp interface xe-0/0/9:0 mode point-to-point
set protocols mstp interface xe-0/0/12:0 cost 1000
set protocols mstp interface xe-0/0/12:0 mode point-to-point
set protocols mstp interface xe-0/0/11:0 cost 1000
set protocols mstp interface xe-0/0/11:0 mode point-to-point
set protocols mstp msti 1 bridge-priority 16k
set protocols mstp msti 1 vlan [10 20]
set protocols mstp msti 1 interface xe-0/0/11:0 cost 1000
set protocols mstp msti 2 bridge-priority 8k
set protocols mstp msti 2 vlan [30 40]

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Step-by-Step Procedure

To configure interfaces and MSTP on Switch 1:

Note:

Starting with Junos OS Release 15.1 for EX Series and QFX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style, you can configure spanning tree parameters globally on all spanning tree interfaces. See Configuring MSTP on Switches for additional information.

Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:

content_copy zoom_out_map
[edit vlans]
user@switch1# set voice-vlan description “Voice VLAN”
user@switch1# set voice-vlan vlan-id 10
user@switch1# set employee-vlan description “Employee VLAN”
user@switch1# set employee-vlan vlan-id 20
user@switch1# set guest-vlan description “Guest VLAN”
user@switch1# set guest-vlan vlan-id 30
user@switch1# set camera-vlan description “Camera VLAN”
user@switch1# set guest-vlan vlan-id 40
      

Configure the VLANs on the interfaces, including support for the Ethernet Switching protocol:

content_copy zoom_out_map
[edit interfaces]
user@switch1# set xe-0/0/9:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch1# set xe-0/0/12:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch1# set xe-0/0/11:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
      

Configure the port mode for the interfaces:

content_copy zoom_out_map
[edit interfaces]
user@switch1# set xe-0/0/9:0 unit 0 family ethernet-switching interface-mode trunk
user@switch1# set xe-0/0/12:0 unit 0 family ethernet-switching interface-mode trunk
user@switch1# set xe-0/0/11:0 unit 0 family ethernet-switching interface-mode trunk      

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Configure MSTP on the switch, including the two MSTIs:

content_copy zoom_out_map
[edit protocols]
user@switch1# mstp configuration-name region1
user@switch1# mstp bridge-priority 16k
user@switch1# mstp interface xe-0/0/9:0 cost 1000
user@switch1# mstp interface xe-0/0/9:0 mode point-to-point
user@switch1# mstp interface xe-0/0/12:0 cost 1000
user@switch1# mstp interface xe-0/0/12:0 mode point-to-point
user@switch1# mstp interface xe-0/0/11:0 cost 1000
user@switch1# mstp interface xe-0/0/11:0 mode point-to-point
user@switch1# mstp msti 1 bridge-priority 16k
user@switch1# mstp msti 1 vlan [10 20]
user@switch1# mstp msti 1 interface xe-0/0/11:0 cost 1000
user@switch1# mstp msti 2 bridge-priority 8k
user@switch1# mstp msti 2 vlan [30 40]
      

Results

Check the results of the configuration:

content_copy zoom_out_map
user@switch1> show configuration  
interfaces {
    xe-0/0/9:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
    xe-0/0/12:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
    xe-0/0/11:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
}
protocols {
    mstp {
        configuration-name region1;
    bridge-priority 16k;
        interface xe-0/0/9:0 {
            cost 1000;
            mode point-to-point;
        }
        interface xe-0/0/12:0 {
            cost 1000;
            mode point-to-point;
        }
        interface xe-0/0/11:0 {
            cost 1000;
            mode point-to-point;
        }
    msti 1 {
        bridge-priority 16k;
        vlan [ 10 20];
        interface xe-0/0/11:0 {
            cost 1000;
        }
    }
    msti 2 {
        bridge-priority 8k;
        vlan [ 30 40 ];
    }
}
vlans {
    voice-vlan {
        vlan-id 10;
    }
    employee-vlan {
        vlan-id 20;
    }
    guest-vlan {
        vlan-id 30;
    }
    camera-vlan {
        vlan-id 40;
    }
}

Configuring MSTP on Switch 2

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

To quickly configure interfaces and MSTP on Switch 2, copy the following commands and paste them into the switch terminal window:

content_copy zoom_out_map
[edit]
set vlans voice-vlan description “Voice VLAN”
set vlans voice-vlan vlan-id 10
set vlans employee-vlan description “Employee VLAN”
set vlans employee-vlan vlan-id 20
set vlans guest-vlan description “Guest VLAN”
set vlans guest-vlan vlan-id 30
set vlans camera-vlan description “Camera VLAN”
set vlans camera-vlan vlan-id 40
set interfaces xe-0/0/9:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces et-0/0/3 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/9:0 unit 0 family ethernet-switching interface-mode trunk
set interfaces et-0/0/3 unit 0 family ethernet-switching interface-mode trunk
set protocols mstp configuration-name region1
set protocols mstp bridge-priority 32k
set protocols mstp interface xe-0/0/9:0 cost 1000
set protocols mstp interface xe-0/0/9:0 mode point-to-point
set protocols mstp interface et-0/0/3 cost 1000
set protocols mstp interface et-0/0/3 mode point-to-point
set protocols mstp msti 1 bridge-priority 32k
set protocols mstp msti 1 vlan [10 20]
set protocols mstp msti 2 bridge-priority 4k
set protocols mstp msti 2 vlan [30 40]

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Step-by-Step Procedure

To configure interfaces and MSTP on Switch 2:

Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:

content_copy zoom_out_map
[edit vlans]
user@switch2# set voice-vlan description “Voice VLAN”
user@switch2# set voice-vlan vlan-id 10
user@switch2# set employee-vlan description “Employee VLAN”
user@switch2# set employee-vlan vlan-id 20
user@switch2# set guest-vlan description “Guest VLAN”
user@switch2# set guest-vlan vlan-id 30
user@switch2# set camera-vlan vlan-description “Camera VLAN”
user@switch2# set guest-vlan vlan-id 40
      

Configure the VLANs on the interfaces, including support for the Ethernet Switching protocol:

content_copy zoom_out_map
[edit interfaces]
user@switch2# set xe-0/0/9:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch2# set et-0/0/3 unit 0 family ethernet-switching vlan members [10 20 30 40]
      

Configure the port mode for the interfaces:
```
[edit interfaces]
user@switch2# set xe-0/0/9:0 unit 0 family ethernet-switching interface-mode trunk
user@switch2# set et-0/0/3 unit 0 family ethernet-switching interface-mode trunk      
```
Note:
For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk
substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Configure MSTP on the switch, including the two MSTIs:

content_copy zoom_out_map
[edit protocols]
user@switch2# mstp configuration-name region1
user@switch2# mstp bridge-priority 32k
user@switch2# mstp interface xe-0/0/9:0 cost 1000
user@switch2# mstp interface xe-0/0/9:0 mode point-to-point
user@switch2# mstp interface et-0/0/3 cost 1000
user@switch2# mstp interface et-0/0/3 mode point-to-point
user@switch2# mstp msti 1 bridge-priority 32k
user@switch2# mstp msti 1 vlan [10 20]
user@switch2# mstp msti 2 bridge-priority 4k
user@switch2# mstp msti 2 vlan [30 40]
      

Results

Check the results of the configuration:

content_copy zoom_out_map
user@switch2> show configuration  
interfaces {
    xe-0/0/9:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
    et-0/0/3 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
}
protocols {
    mstp {
        configuration-name region1;
        bridge-priority 32k;
        interface xe-0/0/9:0 {
            cost 1000;
            mode point-to-point;
        }
        interface et-0/0/3 {
            cost 1000;
            mode point-to-point;
        }
        msti 1 {
            bridge-priority 32k;
            vlan [10 20];
        }
        msti 2 {
            bridge-priority 4k;
            vlan [30 40];
        }
    }
}
vlans {
    voice-vlan {
        vlan-id 10;
    }
    employee-vlan {
        vlan-id 20;
    }
    guest-vlan {
        vlan-id 30;
    }
    camera-vlan {
        vlan-id 40;
    }
}

Configuring MSTP on Switch 3

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

To quickly configure interfaces and MSTP on Switch 3, copy the following commands and paste them into the switch terminal window:

content_copy zoom_out_map
[edit]
set vlans voice-vlan description “Voice VLAN”
set vlans voice-vlan vlan-id 10
set vlans employee-vlan description “Employee VLAN”
set vlans employee-vlan vlan-id 20
set vlans guest-vlan description “Guest VLAN”
set vlans guest-vlan vlan-id 30
set vlans camera-vlan description “Camera VLAN”
set vlans camera-vlan vlan—id 40
set interfaces xe-0/0/11:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces et-0/0/6 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/21:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/11:0 unit 0 family ethernet-switching interface-mode trunk
set interfaces et-0/0/6 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/0/21:0 unit 0 family ethernet-switching interface-mode trunk
set protocols mstp configuration-name region1
set protocols mstp bridge-priority 8k
set protocols mstp interface xe-0/0/11:0 cost 1000
set protocols mstp interface xe-0/0/11:0 mode point-to-point
set protocols mstp interface et-0/0/6 cost 1000
set protocols mstp interface et-0/0/6 mode point-to-point
set protocols mstp interface xe-0/0/21:0 cost 1000
set protocols mstp interface xe-0/0/21:0 mode point-to-point
set protocols mstp msti 1 bridge-priority 4k
set protocols mstp msti 1 vlan [10 20]
set protocols mstp msti 2 bridge-priority 16k
set protocols mstp msti 2 vlan [30 40]

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Step-by-Step Procedure

To configure interfaces and MSTP on Switch 3:

Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:

content_copy zoom_out_map
[edit vlans]
user@switch3# set voice-vlan description “Voice VLAN”
user@switch3# set voice-vlan vlan-id 10
user@switch3# set employee-vlan description “Employee VLAN”
user@switch3# set employee-vlan vlan-id 20
user@switch3# set guest-vlan description “Guest VLAN”
user@switch3# set guest-vlan vlan-id 30
user@switch3# set camera-vlan description “Camera VLAN”
user@switch3# set guest-vlan vlan-id 40
      

Configure the VLANs on the interfaces, including support for the Ethernet Switching protocol:

content_copy zoom_out_map
[edit interfaces]
user@switch3# set xe-0/0/11:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch3# set et-0/0/6 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch3# set xe-0/0/21:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
      

Configure the port mode for the interfaces:

content_copy zoom_out_map
[edit interfaces]
user@switch3# set xe-0/0/11:0 unit 0 family ethernet-switching interface-mode trunk
user@switch3# set et-0/0/6 unit 0 family ethernet-switching interface-mode trunk
user@switch3# set xe-0/0/21:0 unit 0 family ethernet-switching interface-mode trunk      

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Configure MSTP on the switch, including the two MSTIs:

content_copy zoom_out_map
[edit protocols]
user@switch3# mstp configuration-name region1
user@switch3# mstp bridge-priority 8k
user@switch3# mstp interface xe-0/0/11:0 cost 1000
user@switch3# mstp interface xe-0/0/11:0 mode point-to-point
user@switch3# mstp interface et-0/0/6 cost 1000
user@switch3# mstp interface et-0/0/6 mode point-to-point
user@switch3# mstp interface xe-0/0/21:0 cost 1000
user@switch3# mstp interface xe-0/0/21:0 mode point-to-point
user@switch3# mstp msti 1 bridge-priority 4k
user@switch3# mstp msti 1 vlan [10 20]
user@switch3# mstp msti 2 bridge-priority 16k
user@switch3# mstp msti 2 vlan [30 40]
      

Results

Check the results of the configuration:

content_copy zoom_out_map
user@switch3> show configuration  
    interfaces {
        xe-0/0/11:0 {
            unit 0 {
                family ethernet-switching {
                    interface-mode trunk;
                    vlan {
                        members 10;
                        members 20;
                        members 30;
                        members 40;
                    }
                }
            }
        }
        et-0/0/6  {
            unit 0 {
                family ethernet-switching {
                    interface-mode trunk;
                    vlan {
                        members 10;
                        members 20;
                        members 30;
                        members 40;
                    }
                }
            }
        }
        xe-0/0/21:0 {
            unit 0 {
                family ethernet-switching {
                    interface-mode trunk;
                    vlan {
                        members 10;
                        members 20;
                        members 30;
                        members 40;
                    }
                }
            }
        }
    }
}
protocols {
    mstp {
        configuration-name region1;
        bridge-priority 8k;
        interface xe-0/0/11:0 {
            cost 1000;
            mode point-to-point;
        }
        interface et-0/0/6  {
            cost 1000;
            mode point-to-point;
        }
        interface xe-0/0/21:0 {
            cost 1000;
            mode point-to-point;
        }
        msti 1 {
            bridge-priority 4k;
            vlan [10 20];
        }
        msti 2 {
            bridge-priority 16k;
            vlan [30 40];
        }
    }
}
vlans {
    voice-vlan {
        vlan-id 10;
    }
    employee-vlan {
        vlan-id 20;
    }
    guest-vlan {
        vlan-id 30;
    }
    camera-vlan {
        vlan-id 40;
    }
}

Configuring MSTP on Switch 4

Procedure

CLI Quick Configuration
Step-by-Step Procedure
Results

CLI Quick Configuration

To quickly configure interfaces and MSTP on Switch 4, copy the following commands and paste them into the switch terminal window:

content_copy zoom_out_map
[edit]
set vlans voice-vlan description “Voice VLAN”
set vlans voice-vlan vlan-id 10
set vlans employee-vlan description “Employee VLAN”
set vlans employee-vlan vlan-id 20
set vlans guest-vlan description “Guest VLAN”
set vlans guest-vlan vlan-id 30
set vlans camera-vlan description “Camera VLAN”
set vlans camera-vlan vlan-id 40
set interfaces xe-0/0/12:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/21:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
set interfaces xe-0/0/12:0 unit 0 family ethernet-switching interface-mode trunk
set interfaces xe-0/0/21:0 unit 0 family ethernet-switching interface-mode trunk
set protocols mstp configuration-name region1
set protocols mstp bridge-priority 16k
set protocols mstp interface xe-0/0/12:0 cost 1000
set protocols mstp interface xe-0/0/12:0 mode point-to-point
set protocols mstp interface xe-0/0/21:0 cost 1000
set protocols mstp interface xe-0/0/21:0 mode point-to-point
set protocols mstp msti 1 bridge-priority 16k
set protocols mstp msti 1 vlan [10 20]
set protocols mstp msti 2 bridge-priority 32k
set protocols mstp msti 2 vlan [30 40]

Note:

For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk

substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:

content_copy zoom_out_map
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Step-by-Step Procedure

To configure interfaces and MSTP on Switch 4:

Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:

content_copy zoom_out_map
[edit vlans]
user@switch4# set voice-vlan description “Voice VLAN”
user@switch4# set voice-vlan vlan-id 10
user@switch4# set employee-vlan description “Employee VLAN”
user@switch4# set employee-vlan vlan-id 20
user@switch4# set guest-vlan description “Guest VLAN”
user@switch4# set guest-vlan vlan-id 30
user@switch4# set camera-vlan description “Camera VLAN”
user@switch4# set guest-vlan vlan-id 40
      

Configure the VLANs on the interfaces, including support for the Ethernet Switching protocol:

content_copy zoom_out_map
[edit interfaces]
user@switch4# set xe-0/0/12:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch4# set xe-0/0/21:0 unit 0 family ethernet-switching vlan members [10 20 30 40]
      

Configure the port mode for the interfaces:
```
[edit interfaces]
user@switch4# set xe-0/0/12:0 unit 0 family ethernet-switching interface-mode trunk
user@switch4# set xe-0/0/21:0 unit 0 family ethernet-switching interface-mode trunk      
```
Note:
For non-ELS switches, instead of the following command used above for ELS switches that sets an interface into trunk mode using the interface-mode statement:
set interfaces interface-name unit 0 family ethernet-switching interface-mode trunk
substitute the following command for those lines in the configuration, which uses the non-ELS port-mode statement to set an interface into trunk mode:
set interfaces interface-name unit 0 family ethernet-switching port-mode trunk

Configure MSTP on the switch, including the two MSTIs:

content_copy zoom_out_map
[edit protocols]
user@switch4# mstp configuration-name region1
user@switch4# mstp bridge-priority 16k
user@switch4# mstp interface xe-0/0/12:0 cost 1000
user@switch4# mstp interface xe-0/0/12:0 mode point-to-point
user@switch4# mstp interface xe-0/0/21:0 cost 1000
user@switch4# mstp interface xe-0/0/21:0 mode point-to-point
user@switch4# mstp msti 1 bridge-priority 16k
user@switch4# mstp msti 1 vlan [10 20]
user@switch4# mstp msti 2 bridge-priority 32k
user@switch4# mstp msti 2 vlan [30 40]
      

Results

Check the results of the configuration:

content_copy zoom_out_map
user@switch4> show configuration  
interfaces {
    xe-0/0/12:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
    xe-0/0/21:0 {
        unit 0 {
            family ethernet-switching {
                interface-mode trunk;
                vlan {
                    members 10;
                    members 20;
                    members 30;
                    members 40;
                }
            }
        }
    }
}
protocols {
    mstp {
        configuration-name region1;
        bridge-priority 16k;
        interface xe-0/0/12:0 {
            cost 1000;
            mode point-to-point;
        }
        interface xe-0/0/21:0 {
            cost 1000;
            mode point-to-point;
        }
        msti 1 {
            bridge-priority 16k;
            vlan [10 20];
        }
        msti 2 {
            bridge-priority 32k;
            vlan [30 40];
        }
    }
}
vlans {
    voice-vlan {
        vlan-id 10;
    }
    employee-vlan {
        vlan-id 20;
    }
    guest-vlan {
        vlan-id 30;
    }
    camera-vlan {
        vlan-id 40;
    }
}

Verification

To confirm that the configuration is working properly, perform these tasks:

Verifying MSTP Configuration on Switch 1
Verifying MSTP Configuration on Switch 2
Verifying MSTP Configuration on Switch 3
Verifying MSTP Configuration on Switch 4

Verifying MSTP Configuration on Switch 1

Purpose
Action
Meaning

Purpose

Verify the MSTP configuration on Switch 1.

Action

Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:

content_copy zoom_out_map
user@switch1> show spanning-tree interface

Spanning tree interface parameters for instance 0

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/9:0                128:1010     128:1010  16384.544b8c432703         1000    FWD    DESG 
xe-0/0/12:0               128:1011     128:1011  16384.40a677792303         1000    BLK    ALT  
xe-0/0/11:0               128:1012     128:1010   8192.544b8c44c103         1000    FWD    ROOT 

Spanning tree interface parameters for instance 1

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/9:0                128:1010     128:1010  16385.544b8c432703         1000    FWD    DESG 
xe-0/0/12:0               128:1011     128:1011  16385.40a677792303         1000    BLK    ALT  
xe-0/0/11:0               128:1012     128:1010   4097.544b8c44c103         1000    FWD    ROOT 

Spanning tree interface parameters for instance 2

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/9:0                128:1010     128:1012   4098.88a25e8c7603         1000    FWD    ROOT 
xe-0/0/12:0               128:1011     128:1011   8194.544b8c432703         1000    FWD    DESG 
xe-0/0/11:0               128:1012     128:1012   8194.544b8c432703         1000    FWD    DESG 


user@switch1> show spanning-tree bridge

STP bridge parameters 
Routing instance name               : GLOBAL
Context ID                          : 0
Enabled protocol                    : MSTP

STP bridge parameters for CIST
  Root ID                           : 8192.54:4b:8c:44:c1:03
  Root cost                         : 0
  Root port                         : xe-0/0/11:0
  CIST regional root                : 8192.54:4b:8c:44:c1:03
  CIST internal root cost           : 1000
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Message age                       : 0 
  Number of topology changes        : 3
  Time since last topology change   : 675 seconds
  Local parameters 
    Bridge ID                       : 16384.54:4b:8c:43:27:03

STP bridge parameters for MSTI 1
  MSTI regional root                : 4097.54:4b:8c:44:c1:03
  Root cost                         : 1000
  Root port                         : xe-0/0/11:0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Number of topology changes        : 3
  Time since last topology change   : 675 seconds
  Local parameters 
    Bridge ID                       : 16385.54:4b:8c:43:27:03

STP bridge parameters for MSTI 2
  MSTI regional root                : 4098.88:a2:5e:8c:76:03
  Root cost                         : 1000
  Root port                         : xe-0/0/9:0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Number of topology changes        : 3
  Time since last topology change   : 675 seconds
  Local parameters 
    Bridge ID                       : 8194.54:4b:8c:43:27:03
 

Meaning

The operational mode command show spanning-tree interface displays spanning-tree domain information such as the designated port and the port roles.

The operational mode command show spanning-tree bridge displays the spanning-tree domain information at either the bridge level or the interface level. If the optional interface name is omitted, all interfaces in the spanning-tree domain are displayed.

Verifying MSTP Configuration on Switch 2

Purpose
Action
Meaning

Purpose

Verify the MSTP configuration on Switch 2.

Action

Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:

content_copy zoom_out_map
user@switch2> show spanning-tree bridge

Spanning tree interface parameters for instance 0

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
et-0/0/3                  128:1010     128:1011   8192.544b8c44c103         1000    FWD    ROOT 
xe-0/0/9:0                128:1012     128:1010  16384.544b8c432703         1000    BLK    ALT  

Spanning tree interface parameters for instance 1

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
et-0/0/3                  128:1010     128:1011   4097.544b8c44c103         1000    FWD    ROOT 
xe-0/0/9:0                128:1012     128:1010  16385.544b8c432703         1000    BLK    ALT  

Spanning tree interface parameters for instance 2

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
et-0/0/3                  128:1010     128:1010   4098.88a25e8c7603         1000    FWD    DESG 
xe-0/0/9:0                128:1012     128:1012   4098.88a25e8c7603         1000    FWD    DESG 


user@switch2> show spanning-tree bridge

STP bridge parameters
Routing instance name               : GLOBAL
Context ID                          : 0
Enabled protocol                    : MSTP

STP bridge parameters for CIST
  Root ID                           : 8192.54:4b:8c:44:c1:03
  Root cost                         : 0
  Root port                         : et-0/0/3
  CIST regional root                : 8192.54:4b:8c:44:c1:03
  CIST internal root cost           : 1000
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19
  Message age                       : 0
  Number of topology changes        : 2
  Time since last topology change   : 659 seconds
  Local parameters
    Bridge ID                       : 32768.88:a2:5e:8c:76:03

STP bridge parameters for MSTI 1
  MSTI regional root                : 4097.54:4b:8c:44:c1:03
  Root cost                         : 1000
  Root port                         : et-0/0/3
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19
  Number of topology changes        : 2
  Time since last topology change   : 659 seconds
  Local parameters
    Bridge ID                       : 32769.88:a2:5e:8c:76:03

STP bridge parameters for MSTI 2
  MSTI regional root                : 4098.88:a2:5e:8c:76:03
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Number of topology changes        : 3
  Time since last topology change   : 655 seconds
  Local parameters
    Bridge ID                       : 4098.88:a2:5e:8c:76:03

Meaning

The operational mode command show spanning-tree interface displays spanning-tree domain information such as the designated port and the port roles. The spanning-tree interface parameters for instance 2 show that both ports are designated ports, which means Switch 2 is the root bridge for this instance.

The operational mode command show spanning-tree bridge displays the spanning-tree domain information at either the bridge level or interface level. If the optional interface name is omitted, all interfaces in the spanning-tree domain are displayed.

Verifying MSTP Configuration on Switch 3

Purpose
Action
Meaning

Purpose

Verify the MSTP configuration on Switch 3.

Action

Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:

content_copy zoom_out_map
user@switch3> show spanning-tree interface

Spanning tree interface parameters for instance 0

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/11:0               128:1010     128:1010   8192.544b8c44c103         1000    FWD    DESG 
et-0/0/6                  128:1011     128:1011   8192.544b8c44c103         1000    FWD    DESG 
xe-0/0/21:0               128:1012     128:1012   8192.544b8c44c103         1000    FWD    DESG 

Spanning tree interface parameters for instance 1

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/11:0               128:1010     128:1010   4097.544b8c44c103         1000    FWD    DESG 
et-0/0/6                  128:1011     128:1011   4097.544b8c44c103         1000    FWD    DESG 
xe-0/0/21:0               128:1012     128:1012   4097.544b8c44c103         1000    FWD    DESG 

Spanning tree interface parameters for instance 2

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/11:0               128:1010     128:1012   8194.544b8c432703         1000    BLK    ALT  
et-0/0/6                  128:1011     128:1010   4098.88a25e8c7603         1000    FWD    ROOT 
xe-0/0/21:0               128:1012     128:1012  16386.544b8c44c103         1000    FWD    DESG 

 

user@switch3> show spanning-tree bridge

STP bridge parameters 
Routing instance name               : GLOBAL
Context ID                          : 0
Enabled protocol                    : MSTP

STP bridge parameters for CIST
  Root ID                           : 8192.54:4b:8c:44:c1:03
  CIST regional root                : 8192.54:4b:8c:44:c1:03
  CIST internal root cost           : 0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Number of topology changes        : 2
  Time since last topology change   : 786 seconds
  Local parameters 
    Bridge ID                       : 8192.54:4b:8c:44:c1:03

STP bridge parameters for MSTI 1
  MSTI regional root                : 4097.54:4b:8c:44:c1:03
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Number of topology changes        : 1
  Time since last topology change   : 786 seconds
  Local parameters 
    Bridge ID                       : 4097.54:4b:8c:44:c1:03

STP bridge parameters for MSTI 2
  MSTI regional root                : 4098.88:a2:5e:8c:76:03
  Root cost                         : 1000
  Root port                         : et-0/0/6
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Number of topology changes        : 1
  Time since last topology change   : 786 seconds
  Local parameters 
    Bridge ID                       : 16386.54:4b:8c:44:c1:03

Meaning

The operational mode command show spanning-tree interface displays spanning-tree domain information such as the designated port and the port roles. Switch 3 is the root bridge for instance 0, which is the CIST, as well as for instance 1. In both instances, all ports on Switch 3 are designated ports.

Verifying MSTP Configuration on Switch 4

Purpose
Action
Meaning

Purpose

Verify the MSTP configuration on Switch 4.

Action

Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:

content_copy zoom_out_map
user@switch4> show spanning-tree interface

Spanning tree interface parameters for instance 0

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/12:0               128:1011     128:1011  16384.40a677792303         1000    FWD    DESG 
xe-0/0/21:0               128:1012     128:1012   8192.544b8c44c103         1000    FWD    ROOT 

Spanning tree interface parameters for instance 1

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/12:0               128:1011     128:1011  16385.40a677792303         1000    FWD    DESG 
xe-0/0/21:0               128:1012     128:1012   4097.544b8c44c103         1000    FWD    ROOT 

Spanning tree interface parameters for instance 2

Interface                  Port ID    Designated         Designated         Port    State  Role
                                       port ID           bridge ID          Cost
xe-0/0/12:0               128:1011     128:1011   8194.544b8c432703         1000    FWD    ROOT 
xe-0/0/21:0               128:1012     128:1012  16386.544b8c44c103         1000    BLK    ALT  
 


user@switch4> show spanning-tree bridge

STP bridge parameters 
Routing instance name               : GLOBAL
Context ID                          : 0
Enabled protocol                    : MSTP

STP bridge parameters for CIST
  Root ID                           : 8192.54:4b:8c:44:c1:03
  Root cost                         : 0
  Root port                         : xe-0/0/21:0
  CIST regional root                : 8192.54:4b:8c:44:c1:03
  CIST internal root cost           : 1000
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Message age                       : 0 
  Number of topology changes        : 2
  Time since last topology change   : 823 seconds
  Local parameters 
    Bridge ID                       : 16384.40:a6:77:79:23:03

STP bridge parameters for MSTI 1
  MSTI regional root                : 4097.54:4b:8c:44:c1:03
  Root cost                         : 1000
  Root port                         : xe-0/0/21:0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 19 
  Number of topology changes        : 2
  Time since last topology change   : 823 seconds
  Local parameters 
    Bridge ID                       : 16385.40:a6:77:79:23:03

STP bridge parameters for MSTI 2
  MSTI regional root                : 4098.88:a2:5e:8c:76:03
  Root cost                         : 2000
  Root port                         : xe-0/0/12:0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Hop count                         : 18 
  Number of topology changes        : 2
  Time since last topology change   : 823 seconds
  Local parameters 
    Bridge ID                       : 32770.40:a6:77:79:23:03
 

Meaning

The operational mode command show spanning-tree interface displays spanning-tree domain information such as the designated port and the port roles.

Disabling MSTP

To disable the entire MSTP instance:

Include the disable statement. You can include this statement at the following hierarchy levels:
- [edit logical-systems logical-system-name protocols mstp]
- [edit logical-systems logical-system-name routing-instances routing-instance-name protocols mstp]
- [edit protocols mstp]
- [edit routing-instances routing-instance-name protocols mstp]

Change History Table

Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.

Release

Description

15.1

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Spanning-Tree Protocols User Guide

ON THIS PAGE

Configuring MSTP

Understanding MSTP

Benefits of MSTP

MSTP Maps Multiple VLANs

Configuring MSTP Regions

Selecting a Spanning Tree Protocol

See Also

Configuring MSTP

See Also

Configuring MSTP Instances on a Physical Interface

Example: Configuring Network Regions for VLANs with MSTP

Requirements

Overview and Topology

Topology

Configuring MSTP on Switch 1

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Configuring MSTP on Switch 2

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Configuring MSTP on Switch 3

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Configuring MSTP on Switch 4

Procedure

CLI Quick Configuration

Step-by-Step Procedure

Results

Verification

Verifying MSTP Configuration on Switch 1

Purpose

Action

Meaning

Verifying MSTP Configuration on Switch 2

Purpose

Action

Meaning

Verifying MSTP Configuration on Switch 3

Purpose

Action

Meaning

Verifying MSTP Configuration on Switch 4

Purpose

Action

Meaning

Disabling MSTP

Change History Table

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