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Example: Configuring Network Regions for VLANs with MSTP on EX Series Switches
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
This example uses the following hardware and software components:
- Junos OS Release 9.0 or later for EX Series switches
- Four EX 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.
Figure 1: Network Topology for MSTP
The interfaces shown in Figure 1 will be configured for MSTP.
 | Note: You can configure MSTP on logical or physical interfaces. This example shows configuring MSTP on logical interfaces. |
Table 1: 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:
|
Switch 2 | The following interfaces on Switch 2 are connected in this way:
|
Switch 3 | The following interfaces on Switch 3 are connected in this way:
|
Switch 4 | The following interfaces on Switch 4 are connected in this way:
|
VLAN names and tag IDs | voice-vlan, tag 10 |
MSTIs | 1 |
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, copy the following commands and paste them into the switch terminal window:
[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 ge-0/0/13
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge–0/0/9
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge–0/0/11
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge–0/0/13
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/9
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/11
unit 0 family ethernet-switching port-mode trunk
set protocols mstp
configuration-name region1 set protocols mstp
bridge-priority 16k set protocols mstp
interface ge-0/0/13.0 cost 1000 set protocols mstp
interface ge-0/0/13.0 mode point-to-point
set protocols mstp
interface ge-0/0/9.0 cost 1000 set protocols mstp
interface ge-0/0/9.0 mode point-to-point
set protocols mstp
interface ge-0/0/11.0 cost 1000 set protocols mstp
interface ge-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 ge-0/0/11.0 cost 1000
set protocols mstp
msti 2 bridge-priority 8k set protocols mstp
msti 2 vlan [30 40] Step-by-Step Procedure
To configure interfaces and MSTP on Switch 1:
- Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:
[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:
[edit interfaces]
user@switch1# set ge–0/0/13 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch1# set ge-0/0/9 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch1# set ge-0/0/11 unit 0 family ethernet-switching vlan members [10 20 30 40]
- Configure the port mode for the interfaces:
[edit interfaces]
user@switch1# set ge–0/0/13 unit 0 family ethernet-switching port-mode trunk
user@switch1# set ge-0/0/9 unit 0 family ethernet-switching port-mode trunk
user@switch1# set ge-0/0/11 unit 0 family ethernet-switching port-mode trunk - Configure MSTP on the switch, including the two MSTIs:
[edit protocols]
user@switch1# mstp configuration-name region1
user@switch1# mstp bridge-priority 16k
user@switch1# mstp interface ge-0/0/13.0 cost 1000
user@switch1# mstp interface ge-0/0/13.0 mode point-to-point
user@switch1# mstp interface ge-0/0/9.0 cost 1000
user@switch1# mstp interface ge-0/0/9.0 mode point-to-point
user@switch1# mstp interface ge-0/0/11.0 cost 1000
user@switch1# mstp interface ge-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 ge-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:
user@switch1> show configuration
interfaces {ge-0/0/13 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/9 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/11 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}}
protocols {mstp {configuration-name region1;bridge-priority 16k;interface ge-0/0/13.0 {cost 1000;mode point-to-point;}interface ge-0/0/9.0 {cost 1000;mode point-to-point;}interface ge-0/0/11.0 {cost 1000;mode point-to-point;}msti 1 {bridge-priority 16k;vlan [ 10 20];interface ge-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
CLI Quick Configuration
To quickly configure interfaces and MSTP on Switch 2, copy the following commands and paste them into the switch terminal window:
[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 ge–0/0/14
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge-0/0/18
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge-0/0/14
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/18
unit 0 family ethernet-switching port-mode trunk
set protocols mstp
configuration-name region1 set protocols mstp
bridge-priority 32k set protocols mstp
interface ge-0/0/14.0 cost 1000 set protocols mstp
interface ge-0/0/14.0 mode point-to-point
set protocols mstp
interface ge-0/0/18.0 cost 1000 set protocols mstp
interface ge-0/0/18.0 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] Step-by-Step Procedure
To configure interfaces and MSTP on Switch 2:
- Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:
[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:
[edit interfaces]
user@switch2# set ge-0/0/14 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch2# set ge-0/0/18 unit 0 family ethernet-switching vlan members [10 20 30 40]
- Configure the port mode for the interfaces:
[edit interfaces]
user@switch2# set ge-0/0/14 unit 0 family ethernet-switching port-mode trunk
user@switch2# set ge-0/0/18 unit 0 family ethernet-switching port-mode trunk - Configure MSTP on the switch, including the two MSTIs:
[edit protocols]
user@switch2# mstp configuration-name region1
user@switch2# mstp bridge-priority 32k
user@switch2# mstp interface ge-0/0/14.0 cost 1000
user@switch2# mstp interface ge-0/0/14.0 mode point-to-point
user@switch2# mstp interface ge-0/0/18.0 cost 1000
user@switch2# mstp interface ge-0/0/18.0 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:
user@switch2> show configuration
interfaces {ge-0/0/14 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/18 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}}
protocols {mstp {configuration-name region1;bridge-priority 32k;interface ge-0/0/14.0 {cost 1000;mode point-to-point;}interface ge-0/0/18.0 {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
CLI Quick Configuration
To quickly configure interfaces and MSTP on Switch 3, copy the following commands and paste them into the switch terminal window:
[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 ge–0/0/26
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge–0/0/28
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge–0/0/24
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge-0/0/26
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/28
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/24
unit 0 family ethernet-switching port-mode trunk
set protocols mstp
configuration-name region1 set protocols mstp
bridge-priority 8k set protocols mstp
interface ge-0/0/26.0 cost 1000 set protocols mstp
interface ge-0/0/26.0 mode point-to-point
set protocols mstp
interface ge-0/0/28.0 cost 1000 set protocols mstp
interface ge-0/0/28.0 mode point-to-point
set protocols mstp
interface ge-0/0/24.0 cost 1000 set protocols mstp
interface ge-0/0/24.0 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] Step-by-Step Procedure
To configure interfaces and MSTP on Switch 3:
- Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:
[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:
[edit interfaces]
user@switch3# set ge-0/0/26 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch3# set ge-0/0/28 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch3# set ge-0/0/24 unit 0 family ethernet-switching vlan members [10 20 30 40]
- Configure the port mode for the interfaces:
[edit interfaces]
user@switch3# set ge-0/0/26 unit 0 family ethernet-switching port-mode trunk
user@switch3# set ge-0/0/28 unit 0 family ethernet-switching port-mode trunk
user@switch3# set ge-0/0/24 unit 0 family ethernet-switching port-mode trunk - Configure MSTP on the switch, including the two MSTIs:
[edit protocols]
user@switch3# mstp configuration-name region1
user@switch3# mstp bridge-priority 8k
user@switch3# mstp interface ge-0/0/26.0 cost 1000
user@switch3# mstp interface ge-0/0/26.0 mode point-to-point
user@switch3# mstp interface ge-0/0/28.0 cost 1000
user@switch3# mstp interface ge-0/0/28.0 mode point-to-point
user@switch3# mstp interface ge-0/0/24.0 cost 1000
user@switch3# mstp interface ge-0/0/24.0 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:
user@switch3> show configuration
interfaces {ge-0/0/26 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/28 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/24 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}}}
protocols {mstp {configuration-name region1;bridge-priority 8k;interface ge-0/0/26.0 {cost 1000;mode point-to-point;}interface ge-0/0/28.0 {cost 1000;mode point-to-point;}interface ge-0/0/24.0 {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
CLI Quick Configuration
To quickly configure interfaces and MSTP on Switch 4, copy the following commands and paste them into the switch terminal window:
[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 ge-0/0/23
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge-0/0/19
unit 0 family ethernet-switching vlan members [10 20 30 40] set interfaces ge-0/0/23
unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/19
unit 0 family ethernet-switching port-mode trunk
set protocols mstp
configuration-name region1 set protocols mstp
bridge-priority 16k set protocols mstp
interface ge-0/0/23.0 cost 1000 set protocols mstp
interface ge-0/0/23.0 mode point-to-point
set protocols mstp
interface ge-0/0/19.0 cost 1000 set protocols mstp
interface ge-0/0/19.0 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] Step-by-Step Procedure
To configure interfaces and MSTP on Switch 4:
- Configure the VLANs voice-vlan, employee-vlan, guest-vlan, and camera-vlan:
[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:
[edit interfaces]
user@switch4# set ge-0/0/23 unit 0 family ethernet-switching vlan members [10 20 30 40]
user@switch4# set ge-0/0/19 unit 0 family ethernet-switching vlan members [10 20 30 40]
- Configure the port mode for the interfaces:
[edit interfaces]
user@switch4# set ge-0/0/23 unit 0 family ethernet-switching port-mode trunk
user@switch4# set ge-0/0/19 unit 0 family ethernet-switching port-mode trunk - Configure MSTP on the switch, including the two MSTIs:
[edit protocols]
user@switch4# mstp configuration-name region1
user@switch4# mstp bridge-priority 16k
user@switch4# mstp interface ge-0/0/23.0 cost 1000
user@switch4# mstp interface ge-0/0/23.0 mode point-to-point
user@switch4# mstp interface ge-0/0/19.0 cost 1000
user@switch4# mstp interface ge-0/0/19.0 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:
user@switch4> show configuration
interfaces {ge-0/0/23 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}ge-0/0/19 {unit 0 {family ethernet-switching {port-mode trunk;vlan {members 10;members 20;members 30;members 40;}}}}}
protocols {mstp {configuration-name region1;bridge-priority 16k;interface ge-0/0/23.0 {cost 1000;mode point-to-point;}interface ge-0/0/19.0 {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
Verify the MSTP configuration on Switch 1.
Action
Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:
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
ge-0/0/13.0 128:527 128:525 16384.0019e25040e0 1000 BLK ALT
ge-0/0/9.0 128:529 128:513 32768.0019e2503d20 1000 BLK ALT
ge-0/0/11.0 128:531 128:513 8192.0019e25051e0 1000 FWD ROOT
Spanning tree interface parameters for instance 1
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/13.0 128:527 128:525 16384.0019e25040e0 1000 BLK ALT
ge-0/0/9.0 128:529 128:513 32768.0019e2503d20 1000 BLK ALT
ge-0/0/11.0 128:531 128:513 4096.0019e25051e0 1000 FWD ROOT
Spanning tree interface parameters for instance 2
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/13.0 128:527 128:527 8192.0019e25044e0 1000 FWD DESG
ge-0/0/9.0 128:529 128:513 4096.0019e2503d20 1000 FWD ROOT
ge-0/0/11.0 128:531 128:531 8192.0019e25044e0 1000 FWD DESG
user@switch1> show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : MSTP
STP bridge parameters for CIST
Root ID : 8192.00:19:e2:50:51:e0
Root cost : 1000
Root port : ge-0/0/13.0
CIST regional root : 8192.00:19:e2:50:51:e0
CIST internal root cost : 2000
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 18
Message age : 0
Number of topology changes : 3
Time since last topology change : 921 seconds
Local parameters
Bridge ID : 16384.00:19:e2:50:44:e0
Extended system ID : 0
Internal instance ID : 0
STP bridge parameters for MSTI 1
MSTI regional root : 4096.00:19:e2:50:51:e0
Root cost : 1000
Root port : ge-0/0/13.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 18
Local parameters
Bridge ID : 16384.00:19:e2:50:44:e0
Extended system ID : 0
Internal instance ID : 1
STP bridge parameters for MSTI 2
MSTI regional root : 4096.00:19:e2:50:3d:20
Root cost : 1000
Root port : ge-0/0/9.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 19
Local parameters
Bridge ID : 8192.00:19:e2:50:44:e0
Extended system ID : 0
Internal instance ID : 2
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
Verify the MSTP configuration on Switch 2.
Action
Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:
user@switch2> show spanning-tree interface
Spanning tree interface parameters for instance 0
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/14.0 128:513 128:513 32768.0019e2503d20 1000 FWD DESG
ge-0/0/18.0 128:519 128:515 8192.0019e25051e0 1000 FWD ROOT
Spanning tree interface parameters for instance 1
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/14.0 128:513 128:513 32769.0019e2503d20 1000 FWD DESG
ge-0/0/18.0 128:519 128:515 4097.0019e25051e0 1000 FWD ROOT
Spanning tree interface parameters for instance 2
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/14.0 128:513 128:513 4098.0019e2503d20 1000 FWD DESG
ge-0/0/18.0 128:519 128:519 4098.0019e2503d20 1000 FWD DESG
user@switch2> show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : MSTP
STP bridge parameters for CIST
Root ID : 8192.00:19:e2:50:51:e0
Root cost : 1000
Root port : ge-0/0/18.0
CIST regional root : 8192.00:19:e2:50:51:e0
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 : 1
Time since last topology change : 782 seconds
Local parameters
Bridge ID : 32768.00:19:e2:50:3d:20
Extended system ID : 0
Internal instance ID : 0
STP bridge parameters for MSTI 1
MSTI regional root : 4096.00:19:e2:50:51:e0
Root cost : 1000
Root port : ge-0/0/18.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 19
Local parameters
Bridge ID : 32768.00:19:e2:50:3d:20
Extended system ID : 0
Internal instance ID : 1
STP bridge parameters for MSTI 2
MSTI regional root : 4096.00:19:e2:50:3d:20
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Local parameters
Bridge ID : 4096.00:19:e2:50:3d:20
Extended system ID : 0
Internal instance ID : 2Meaning
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
Verify the MSTP configuration on Switch 3.
Action
Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:
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
ge-0/0/26.0 128:513 128:513 8192.0019e25051e0 1000 FWD DESG
ge-0/0/28.0 128:515 128:515 8192.0019e25051e0 1000 FWD DESG
ge-0/0/24.0 128:517 128:517 8192.0019e25051e0 1000 FWD DESG
Spanning tree interface parameters for instance 1
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/26.0 128:513 128:513 4096.0019e25051e0 1000 FWD DESG
ge-0/0/28.0 128:515 128:515 4096.0019e25051e0 1000 FWD DESG
ge-0/0/24.0 128:517 128:517 4096.0019e25051e0 1000 FWD DESG
Spanning tree interface parameters for instance 2
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/26.0 128:513 128:531 8192.0019e25044e0 1000 BLK ALT
ge-0/0/28.0 128:515 128:519 4096.0019e2503d20 1000 FWD ROOT
ge-0/0/24.0 128:517 128:517 16384.0019e25051e0 1000 FWD DESG
user@switch3> show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : MSTP
STP bridge parameters for CIST
Root ID : 8192.00:19:e2:50:51:e0
CIST regional root : 8192.00:19:e2:50:51:e0
CIST internal root cost : 0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Number of topology changes : 3
Time since last topology change : 843 seconds
Local parameters
Bridge ID : 8192.00:19:e2:50:51:e0
Extended system ID : 0
Internal instance ID : 0
STP bridge parameters for MSTI 1
MSTI regional root : 4096.00:19:e2:50:51:e0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Local parameters
Bridge ID : 4096.00:19:e2:50:51:e0
Extended system ID : 0
Internal instance ID : 1
STP bridge parameters for MSTI 2
MSTI regional root : 4096.00:19:e2:50:3d:20
Root cost : 1000
Root port : ge-0/0/28.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 19
Local parameters
Bridge ID : 16384.00:19:e2:50:51:e0
Extended system ID : 0
Internal instance ID : 2
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.
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 4
Purpose
Verify the MSTP configuration on Switch 4.
Action
Issue the operational mode commands show spanning-tree interface and show spanning-tree bridge:
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
ge-0/0/23.0 128:523 128:517 8192.0019e25051e0 1000 FWD ROOT
ge-0/0/19.0 128:525 128:525 16384.0019e25040e0 1000 FWD DESG
Spanning tree interface parameters for instance 1
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/23.0 128:523 128:517 4096.0019e25051e0 1000 FWD ROOT
ge-0/0/19.0 128:525 128:525 16384.0019e25040e0 1000 FWD DESG
Spanning tree interface parameters for instance 2
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/23.0 128:523 128:517 16384.0019e25051e0 1000 BLK ALT
ge-0/0/19.0 128:525 128:527 8192.0019e25044e0 1000 FWD ROOT
user@switch4> show spanning-tree bridge
STP bridge parameters
Context ID : 0
Enabled protocol : MSTP
STP bridge parameters for CIST
Root ID : 8192.00:19:e2:50:51:e0
Root cost : 0
Root port : ge-0/0/23.0
CIST regional root : 8192.00:19:e2:50:51:e0
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 : 4
Time since last topology change : 887 seconds
Local parameters
Bridge ID : 16384.00:19:e2:50:40:e0
Extended system ID : 0
Internal instance ID : 0
STP bridge parameters for MSTI 1
MSTI regional root : 4096.00:19:e2:50:51:e0
Root cost : 1000
Root port : ge-0/0/23.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 19
Local parameters
Bridge ID : 16384.00:19:e2:50:40:e0
Extended system ID : 0
Internal instance ID : 1
STP bridge parameters for MSTI 2
MSTI regional root : 4096.00:19:e2:50:3d:20
Root cost : 2000
Root port : ge-0/0/19.0
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Hop count : 18
Local parameters
Bridge ID : 32768.00:19:e2:50:40:e0
Extended system ID : 0
Internal instance ID : 2
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.
