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Example: Configuring Faster Convergence and Improving Network Stability with RSTP on EX-series Switches

EX-series switches use Rapid Spanning Tree Protocol (RSTP) to provide a loop-free topology. RSTP identifies certain links as point to point. When a point-to-point link fails, the alternate link can transition to the forwarding state. RSTP provides better reconvergence time than original STP because it uses protocol handshake messages rather than fixed timeouts. Eliminating the need to wait for timers to expire makes RSTP more efficient than STP.

This example describes how to configure RSTP on four EX-series switches:

Requirements

This example uses the following hardware and software components:

  • JUNOS Release 9.0 or later for EX-series switches
  • Four EX-series switches

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

Overview and Topology

In this example, four EX-series switches are connected in the topology displayed in Figure 1 to create a loop-free topology.

Figure 1: Network Topology for RSTP

Image g020031.gif

The interfaces shown in Table 1 will be configured for RSTP.

Note: You can configure the RSTP protocol on logical or physical interfaces. This example shows RSTP configured on logical interfaces.

Table 1: Components of the Topology for Configuring RSTP on EX-series Switches

Property

Settings

Switch 1

The following ports on Switch 1 are connected in this way:

  • ge-0/0/9 is connected to Switch 2
  • ge-0/0/13 is connected to Switch 4
  • ge-0/0/11 is connected to Switch 3

Switch 2

The following ports on Switch 2 are connected in this way:

  • ge-0/0/14 is connected to Switch 1
  • ge-0/0/18 is connected to Switch 3

Switch 3

The following ports on Switch 3 are connected in this way:

  • ge-0/0/26 is connected to Switch 1
  • ge-0/0/28 is connected to Switch 2
  • ge-0/0/24 is connected to Switch 4

Switch 4

The following ports on Switch 4 are connected in this way:

  • ge-0/0/19 is connected to Switch 1
  • ge-0/0/23 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

This configuration example creates a loop-free topology between four EX-series switches using RSTP.

An RSTP topology contains ports that 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 is a backup port for the designated port. When a designated port goes down, the backup port becomes the active designated port and starts forwarding data.

Note: You also can create a loop-free topology between the aggregation layer and the distribution layer using redundant trunk links. For more information about configuring redundant trunk links, see Example: Configuring Redundant Trunk Links for Faster Recovery.

Configuring RSTP on Switch 1

To configure RSTP on Switch 1, perform these tasks:

    CLI Quick Configuration

    To quickly configure interfaces and RSTP 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 rstp bridge-priority 16k

    set protocols rstp interface ge-0/0/13.0 cost 1000

    set protocols rstp interface ge-0/0/13.0 mode point-to-point

    set protocols rstp interface ge-0/0/9.0 cost 1000

    set protocols rstp interface ge-0/0/9.0 mode point-to-point

    set protocols rstp interface ge-0/0/11.0 cost 1000

    set protocols rstp interface ge-0/0/11.0 mode point-to-point

    Step-by-Step Procedure

    To configure interfaces and RSTP on Switch 1:

    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
    2. 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]
    3. 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
    4. Configure RSTP on the switch:
      [edit protocols]

      user@switch1# rstp bridge-priority 16k
      user@switch1# rstp interface ge-0/0/13.0 cost 1000
      user@switch1# rstp interface ge-0/0/13.0 mode point-to-point
      user@switch1# rstp interface ge-0/0/9.0 cost 1000
      user@switch1# rstp interface ge-0/0/9.0 mode point-to-point
      user@switch1# rstp interface ge-0/0/11.0 cost 1000
      user@switch1# rstp interface ge-0/0/11.0 mode point-to-point

    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 20 30 40];
    }
    }
    }
    }
    ge-0/0/9 {
    unit 0 {
    family ethernet-switching {
    port-mode trunk;
    vlan {
    members [10 20 30 40];
    }
    }
    }
    }
    ge-0/0/11 {
    unit 0 {
    family ethernet-switching {
    port-mode trunk;
    vlan {
    members [10 20 30 40];
    }
    }
    }
    }
    }
    protocols {
    rstp {
    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;
    }
    }
    }
    }
    vlans {
    voice-vlan {
    vlan-id 10;
    }
    employee-vlan {
    vlan-id 20;
    }
    guest-vlan {
    vlan-id 30;
    }
    camera-vlan {
    vlan-id 40;
    }
    }

    Configuring RSTP on Switch 2

    To configure RSTP on switch 2, perform these tasks:

      CLI Quick Configuration

      To quickly configure interfaces and RSTP 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 rstp bridge-priority 32k

      set protocols rstp interface ge-0/0/14.0 cost 1000

      set protocols rstp interface ge-0/0/14.0 mode point-to-point

      set protocols rstp interface ge-0/0/18.0 cost 1000

      set protocols rstp interface ge-0/0/18.0 mode point-to-point

      Step-by-Step Procedure

      To configure interfaces and RSTP on Switch 2:

      1. 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
      2. 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]
      3. 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
      4. Configure RSTP on the switch:
        [edit protocols]
        user@switch2# rstp bridge-priority 32k
        user@switch2# rstp interface ge-0/0/14.0 cost 1000
        user@switch2# rstp interface ge-0/0/14.0 mode point-to-point
        user@switch2# rstp interface ge-0/0/18.0 cost 1000
        user@switch2# rstp interface ge-0/0/18.0 mode point-to-point

      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 20 30 40];
      }
      }
      }
      }
      ge-0/0/18 {
      unit 0 {
      family ethernet-switching {
      port-mode trunk;
      vlan {
      members [10 20 30 40];
      }
      }
      }
      }
      }
      protocols {
      rstp {
      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;
      }
      }
      }
      }
      vlans {
      voice-vlan {
      vlan-id 10;
      }
      employee-vlan {
      vlan-id 20;
      }
      guest-vlan {
      vlan-id 30;
      }
      camera-vlan {
      vlan-id 40;
      }
      }

      Configuring RSTP on Switch 3

      To configure RSTP on switch 3, perform these tasks:

        CLI Quick Configuration

        To quickly configure interfaces and RSTP 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 rstp bridge-priority 8k

        set protocols rstp interface ge-0/0/26.0 cost 1000

        set protocols rstp interface ge-0/0/26.0 mode point-to-point

        set protocols rstp interface ge-0/0/28.0 cost 1000

        set protocols rstp interface ge-0/0/28.0 mode point-to-point

        set protocols rstp interface ge-0/0/24.0 cost 1000

        set protocols rstp interface ge-0/0/24.0 mode point-to-point

        Step-by-Step Procedure

        To configure interfaces and RSTP on Switch 3:

        1. 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
        2. 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]
        3. 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
        4. Configure RSTP on the switch:
          [edit protocols]
          user@switch3# rstp bridge-priority 8k
          user@switch3# rstp interface ge-0/0/26.0 cost 1000
          user@switch3# rstp interface ge-0/0/26.0 mode point-to-point
          user@switch3# rstp interface ge-0/0/28.0 cost 1000
          user@switch3# rstp interface ge-0/0/28.0 mode point-to-point
          user@switch3# rstp interface ge-0/0/24.0 cost 1000
          user@switch3# rstp interface ge-0/0/24.0 mode point-to-point

        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 20 30 40];
        }
        }
        }
        }
        ge-0/0/28 {
        unit 0 {
        family ethernet-switching {
        port-mode trunk;
        vlan {
        members [10 20 30 40];
        }
        }
        }
        }
        ge-0/0/24 {
        unit 0 {
        family ethernet-switching {
        port-mode trunk;
        vlan {
        members [10 20 30 40];
        }
        }
        }
        }
        }
        }
        protocols {
        rstp {
        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;
        }
        }
        bridge-priority 8k;
        }
        }
        }
        }
        vlans {
        voice-vlan {
        vlan-id 10;
        }
        employee-vlan {
        vlan-id 20;
        }
        guest-vlan {
        vlan-id 30;
        }
        camera-vlan {
        vlan-id 40;
        }
        }

        Configuring RSTP on Switch 4

        To configure RSTP on switch 4, perform these tasks:

          CLI Quick Configuration

          To quickly configure interfaces and RSTP 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 rstp bridge-priority 16k

          set protocols rstp interface ge-0/0/23.0 cost 1000

          set protocols rstp interface ge-0/0/23.0 mode point-to-point

          set protocols rstp interface ge-0/0/19.0 cost 1000

          set protocols rstp interface ge-0/0/19.0 mode point-to-point

          Step-by-Step Procedure

          To configure interfaces and RSTP on Switch 4:

          1. 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
          2. 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]
          3. 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
          4. Configure RSTP on the switch:
            [edit protocols]
            user@switch4# rstp bridge-priority 16k
            user@switch4# rstp interface all cost 1000
            user@switch4# rstp interface ge-0/0/23.0 cost 1000
            user@switch4# rstp interface ge-0/0/23.0 mode point-to-point
            user@switch4# rstp interface ge-0/0/19.0 cost 1000
            user@switch4# rstp interface ge-0/0/19.0 mode point-to-point

          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 20 30 40];
          }
          }
          }
          }
          ge-0/0/19 {
          unit 0 {
          family ethernet-switching {
          port-mode trunk;
          vlan {
          members [10 20 30 40];
          }
          }
          }
          }
          }
          protocols {
          rstp {
          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;
          }
          }
          }
          }
          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 RSTP Configuration on Switch 1

          Purpose

          Verify the RSTP configuration on Switch 1.

          Action

          Use the operational mode command:


          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

          Meaning

          Refer to the topology in Figure 1. The operational mode command show spanning-tree interface shows that ge-0/0/13.0 is in a forwarding state. The other interfaces on Switch 1 are blocking.

          Verifying RSTP Configuration on Switch 2

          Purpose

          Verify the RSTP configuration on Switch 2.

          Action

          Use the operational mode command:


          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  BLK    DESG 
ge-0/0/18.0     128:519      128:515   8192.0019e25051e0      1000  FWD    ROOT

          Meaning

          Refer to the topology in Figure 1. The operational mode command show spanning-tree interface shows that ge-0/0/18.0 is in a forwarding state and the root port. The other interface on Switch 2 is blocking.

          Verifying RSTP Configuration on Switch 3

          Purpose

          Verify the RSTP configuration on Switch 3.

          Action

          Use the operational mode commands:


          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

          Meaning

          Refer to the topology in Figure 1. The operational mode command show spanning-tree interface shows that no interface is the root interface.

          Verifying RSTP Configuration on Switch 4

          Purpose

          Verify the RSTP configuration on Switch 4.

          Action

          Use the operational mode commands:


          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

          Meaning

          Refer to the topology in Figure 1. The operational mode command show spanning-tree interface shows that interface ge-0/0/23.0 is the root interface and forwarding.

          [an error occurred while processing this directive]