Example: Configuring VSTP on a Trunk Port with Tagged Traffic

VSTP on a Trunk Port with Tagged Traffic Overview

Double-tagging can be useful for Internet service providers, allowing them to use VLANs internally while mixing traffic from clients that are already VLAN-tagged.

Example: Configuring VSTP on a Trunk Port with Tagged Traffic

This example shows how to configure the VSTP to send and receive standard untagged Rapid Spanning Tree Protocol (RSTP) bridge protocol data units (BPDUs) on access trunks that interoperate with tagged VSTP BPDUs sent over the double-tagged trunk ports.

• Requirements
• Overview
• Configuration
• Verification

Requirements

• Two CE devices (MX Series routers with DPCE or MPC cards)
• Two PE devices (MX Series routers with DPCE or MPC cards)
• Junos OS Release 12.3 or later running on the PE devices

Overview

This example shows how to configure VSTP on a trunk port with tagged traffic.

Topology

Figure 1 shows a sample topology in which two customer edge (CE) bridges are dual-homed to two provider edge (PE) devices. All of the PE-CE links are single-tagged trunks using C-VLANs 1-100. The core link between Devices PE1 and PE2 is a double-tagged trunk that carries traffic from both CE devices, using S-VLANs 100 and 200 to distinguish the CE traffic.

Two VSTP instances are created on the PE devices, one for each S-VLAN. The CE devices run the standard RSTP. The PE devices run VSTP on the core link while sending standard untagged RSTP BPDUs toward the CE devices.

Figure 1: Topology for VSTP Configured on a Trunk Port with Tagged Traffic

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Configuring PE1, PE2, CE1, and CE2

Step-by-Step Procedure

1. Configure the network interfaces.
   [edit interfaces]user@PE1# set ge-2/0/1 flexible-vlan-tagginguser@PE1# set ge-2/0/1 encapsulation flexible-ethernet-servicesuser@PE1# set ge-2/0/1 unit 1 vlan-id 100user@PE1# set ge-2/0/1 unit 1 family bridge interface-mode trunkuser@PE1# set ge-2/0/1 unit 1 family bridge inner-vlan-id-list 1-100user@PE1# set ge-2/0/1 unit 2 vlan-id 200user@PE1# set ge-2/0/1 unit 2 family bridge interface-mode trunkuser@PE1# set ge-2/0/1 unit 2 family bridge inner-vlan-id-list 1-100
   user@PE1# set ge-2/0/4 encapsulation ethernet-vplsuser@PE1#set ge-2/0/4 unit 0 description to_CE1 user@PE1# set ge-2/0/4 unit 0 family bridge interface-mode trunkuser@PE1#set ge-2/0/4 unit 0 family bridge vlan-id-list 1-100
   user@PE1# set ge-2/1/1 unit 0 description to_CE2user@PE1# set ge-2/1/1 unit 0 family bridge interface-mode trunkuser@PE1# set ge-2/1/1 unit 0 family bridge vlan-id-list 1-100
2. Configure the routing instances.
   [edit routing-instances]user@PE1# set vs1 instance-type virtual-switchuser@PE1# set vs1 interface ge-2/0/1.1user@PE1# set vs1 interface ge-2/0/4.0user@PE1# set vs1 protocols vstp vlan 100 interface ge-2/0/1user@PE1# set vs1 protocols vstp vlan 100 interface ge-2/0/4 access-trunkuser@PE1# set vs1 bridge-domains bd vlan-id-list 1-100
   user@PE1# set vs2 instance-type virtual-switchuser@PE1# set vs2 interface ge-2/0/1.2user@PE1# set vs2 interface ge-2/1/1.0user@PE1# set vs2 protocols vstp vlan 200 interface ge-2/0/1user@PE1# set vs2 protocols vstp vlan 200 interface ge-2/1/1 access-trunkuser@PE1# set vs2 bridge-domains bd vlan-id-list 1-100

Step-by-Step Procedure

1. Configure the interfaces.
   [edit interfaces]user@PE2# set ge-2/0/1 flexible-vlan-tagginguser@PE2# set ge-2/0/1 encapsulation flexible-ethernet-servicesuser@PE2# set ge-2/0/1 unit 1 vlan-id 100user@PE2# set ge-2/0/1 unit 1 family bridge interface-mode trunkuser@PE2# set ge-2/0/1 unit 1 family bridge inner-vlan-id-list 1-100user@PE2# set ge-2/0/1 unit 2 vlan-id 200user@PE2# set ge-2/0/1 unit 2 family bridge interface-mode trunkuser@PE2# set ge-2/0/1 unit 2 family bridge inner-vlan-id-list 1-100
   user@PE2# set ge-2/1/3 description to_CE1user@PE2# set ge-2/1/3 unit 0 family bridge interface-mode trunkuser@PE2# set ge-2/1/3 unit 0 family bridge vlan-id-list 1-100
   user@PE2# set ge-2/0/5 description to_CE2user@PE2# set ge-2/0/5 unit 0 family bridge interface-mode trunkuser@PE2# set ge-2/0/5 unit 0 family bridge vlan-id-list 1-100
2. Configure the routing instances.
   [edit routing-instances]user@PE2# set vs1 instance-type virtual-switchuser@PE2# set vs1 interface ge-2/0/1.1user@PE2# set vs1 interface ge-2/1/3.0user@PE2# set vs1 protocols vstp vlan 100 interface ge-2/0/1user@PE2# set vs1 protocols vstp vlan 100 interface ge-2/1/3 access-trunkuser@PE2# set vs1 bridge-domains bd vlan-id-list 1-100
   user@PE2# set vs2 instance-type virtual-switchuser@PE2# set vs2 interface ge-2/0/1.2user@PE2# set vs2 interface ge-2/0/5.0user@PE2# set vs2 protocols vstp vlan 200 interface ge-2/0/1user@PE2# set vs2 protocols vstp vlan 200 interface ge-2/0/5 access-trunkuser@PE2# set vs2 bridge-domains bd vlan-id-list 1-100

Step-by-Step Procedure

1. Configure the interfaces.
   [edit interfaces]user@CE1# set ge-2/0/7 unit 0 description to_PE1user@CE1# set ge-2/0/7 unit 0 family bridge interface-mode trunkuser@CE1# set ge-2/0/7 unit 0 family bridge vlan-id-list 1-100
   user@CE1# set ge-2/1/4 unit 0 description to_PE2user@CE1# set ge-2/1/4 unit 0 family bridge interface-mode trunkuser@CE1# set ge-2/1/4 unit 0 family bridge vlan-id-list 1-100
2. Configure the protocols.
   [edit protocols]user@CE1# set rstp interface ge-2/0/7user@CE1# set rstp interface ge-2/1/4
3. Configure the bridge domain.
   [edit bridge-domains]user@CE1# set bd vlan-id-list 1-100

Step-by-Step Procedure

1. Configure the interfaces.
   [edit interfaces]user@CE2# set ge-2/0/8 unit 0 description to_PE2user@CE2# set ge-2/0/8 unit 0 family bridge interface-mode trunkuser@CE2# set ge-2/0/8 unit 0 family bridge vlan-id-list 1-100
   user@CE2# set ge-2/1/1 unit 0 description to_PE1user@CE2# set ge-2/1/1 unit 0 family bridge interface-mode trunkuser@CE2# set ge-2/1/1 unit 0 family bridge vlan-id-list 1-100
2. Configure the protocols.
   [edit protocols]user@CE2# set rstp interface ge-2/0/8user@CE2# set rstp interface ge-2/1/1
3. Configure the bridge domain.
   [edit bridge-domains]user@CE2# set bd vlan-id-list 1-100

Results

From configuration mode, confirm your configuration by entering the show interfaces, show routing-instances, show protocols, and show bridge-domains commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

• Verifying That the Interfaces Are Operational
• Verifying the STP Bridge Parameters of the Routing Instances
• Displaying STP Statistics for the Configured Bridge

Verifying That the Interfaces Are Operational

Purpose

Verify that the interfaces are operational.

Action

Spanning tree interface parameters for VLAN 100

Interface    Port ID    Designated      Designated         Port    State  Role
                         port ID        bridge ID          Cost
ge-2/0/1        128:82       128:82  32868.0021590f37d0     20000  FWD    DESG 
ge-2/0/4        128:85       128:85  32868.0021590f37d0     20000  FWD    DESG 

Meaning

The output shows the status of the interfaces configured for VLAN 100.

Verifying the STP Bridge Parameters of the Routing Instances

Purpose

Verify the STP bridge parameters configured for the routing instances.

Action

STP bridge parameters 
Routing instance name               : vs1
Enabled protocol                    : RSTP

STP bridge parameters for VLAN 100
  Root ID                           : 32868.00:21:59:0f:37:d0
  Hello time                        : 2 seconds
  Maximum age                       : 20 seconds
  Forward delay                     : 15 seconds
  Message age                       : 0 
  Number of topology changes        : 2
  Time since last topology change   : 687 seconds
  Local parameters 
    Bridge ID                       : 32868.00:21:59:0f:37:d0
    Extended system ID              : 100

Meaning

The output shows the status of the STP bridge parameters for routing instance vs1.

Displaying STP Statistics for the Configured Bridge

Purpose

Display spanning-tree statistics for the configured bridge.

Action

STP Context  : default
STP Instance : 0  
Number of Root Bridge Changes: 0         
Number of Root Port Changes:   0         

STP Context  : x/default
STP Instance : 0  
Number of Root Bridge Changes: 0         
Number of Root Port Changes:   0         

STP Context  : vs1
STP Instance : 0  
Number of Root Bridge Changes: 2            Last Changed: Thu Sep 20 15:12:18 2012  
Number of Root Port Changes:   1            Last Changed: Thu Sep 20 15:01:13 2012  
Recent TC  Received:  ge-2/0/1.1            Received    : Thu Sep 20 15:01:17 2012   

STP Context  : vs2
STP Instance : 0  
Number of Root Bridge Changes: 2            Last Changed: Thu Sep 20 15:10:25 2012  
Number of Root Port Changes:   2            Last Changed: Thu Sep 20 15:10:25 2012  
Recent TC  Received:  ge-2/1/1.0            Received    : Thu Sep 20 15:10:47 2012   

STP Context  : CE1/default
STP Instance : 0  
Number of Root Bridge Changes: 0         
Number of Root Port Changes:   0         
Recent TC  Received:  ge-2/1/4.0            Received    : Thu Sep 20 15:12:15 2012   

Meaning

The command output shows spanning-tree statistics for the configured bridge.