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Example: Configuring an EX2200 Virtual Chassis with Four Member Switches

 

A Virtual Chassis configuration is a scalable switch. You can provide secure, redundant network accessibility with an EX2200 Virtual Chassis. You can expand the Virtual Chassis configuration to include up to four EX2200 member switches to provide additional access interfaces as your office grows.

This example describes how to configure a four-member EX2200 Virtual Chassis. You can use this configuration with the same hardware and software configurations if the member switches are installed in the same or different wiring closets.

Requirements

This example uses the following hardware and software components:

  • Four EX2200 switches

  • Four Virtual Chassis port (VCP)-configurable optical modules.

    To confirm which optical modules are supported for EX2200 switches and are VCP-configurable, see Pluggable Transceivers Supported on EX2200 Switches.

  • Junos OS Release 12.2 or later for EX Series switches

Before you begin, be sure you have:

  1. Rack-mounted the switches. See Mounting an EX2200 Switch.
  2. Cabled the switches. See Installing and Connecting an EX2200 Switch.

Overview and Topology

This example shows a Virtual Chassis configuration composed of four EX2200 switches. You would typically use a four-member EX2200 Virtual Chassis to add ports at the access layer in a manner that minimized network complexity, or to combine two EX2200 access layer switches at different sites into a single switch. A Virtual Chassis reduces network complexity by allowing a single configuration to be applied to all member switches and by minimizing the need for a loop prevention protocol like Spanning Tree Protocol (STP).

You interconnect EX2200 switches into a Virtual Chassis by configuring uplink ports connecting EX2200 member switches as Virtual Chassis ports (VCPs). You must use the uplink ports configured as VCPs regardless of whether the member switches are installed in the same or different wiring closets.

After you interconnect the switches with the uplink ports and configure them as VCPs, the VCPs are operational. The mastership priorities and member IDs are assigned by the user using the Junos OS software in this example. The software elects a master based on several criteria, including how long a member switch has belonged to the Virtual Chassis configuration. For additional details on how the master switch is elected, see Understanding How the Master in a Virtual Chassis Is Elected.

Note

This example uses a nonprovisioned configuration. You can explicitly assign a role for each member switch by preprovisioning the Virtual Chassis. See Configuring an EX2200 Virtual Chassis (CLI Procedure).

Note

We recommend that you use the commit synchronize command to save any configuration changes that you make to a multimember Virtual Chassis.

The topology for this example consists of four EX2200 switches.

Table 1 shows the default configuration settings for the Virtual Chassis.

Table 1: Components of the Basic Virtual Chassis Access Switch Topology

Member SwitchHardwareMember IDRole and Priority

switch-0

EX2200 switch

0

Master: mastership priority 255

switch-1

EX2200 switch

1

Backup: mastership priority 255

switch-2

EX2200 switch

2

Line card; mastership priority 128

switch-3

EX2200 switch

3

Line card; mastership priority 128

Configuration

Step-by-Step Procedure

To configure a Virtual Chassis with four member switches in a single wiring closet:

  1. Make sure the optical ports on the member switches are properly cabled. See Install a Transceiver.
  2. Power on switch-0 (the member switch that you want to function as the master).
  3. When the CLI prompt becomes available, run the EZSetup program on switch-0, specifying the identification parameters. See Connecting and Configuring an EX Series Switch (CLI Procedure) or Connecting and Configuring an EX Series Switch (J-Web Procedure) for details.
  4. Configure switch-0 with the virtual management Ethernet (VME) interface for out-of-band management of the Virtual Chassis configuration, if desired.
    [edit]

    user@switch-0# set interfaces vme unit 0 family inet address /ip-address/mask/
  5. Configure the mastership priority of the switches that you want to act in the master and backup roles:
    [edit virtual-chassis]

    user@switch-0# set member 0 mastership-priority 255

    user@switch-0# set member 1 mastership-priority 255
  6. Power on switch-1. The default mastership priority selection algorithm uses the amount of time powered on to assign the backup role to a switch, so powering on switch-1 before switch-2 and switch-3 helps ensure the correct roles are assigned to each member switch.
  7. Power on switch-2 and switch-3. You do not need to configure the mastership priority values for these switches since the will use the default priority values of 128.
  8. Configure the optical ports on each switch as VCPs.
    user@switch-0> request virtual-chassis vc-port set pic-slot 1 port 0
    user@switch-0> request virtual-chassis vc-port set pic-slot 1 port 1
    user@switch-1> request virtual-chassis vc-port set pic-slot 1 port 0
    user@switch-1> request virtual-chassis vc-port set pic-slot 1 port 1
    user@switch-2> request virtual-chassis vc-port set pic-slot 1 port 0
    user@switch-2> request virtual-chassis vc-port set pic-slot 1 port 1
    user@switch-3> request virtual-chassis vc-port set pic-slot 1 port 0
    user@switch-3> request virtual-chassis vc-port set pic-slot 1 port 1

Verification

To confirm that the Virtual Chassis is operational, perform these tasks:

Verifying That the Member Switches are Present and the Roles are Properly Assigned

Purpose

Verify that the member switches are present in the Virtual Chassis and that the master switch, which has been selected by default, is the member switch that you want to function in that role.

Action

List the member switches of the Virtual Chassis configuration:

user@switch-0> show virtual-chassis


Meaning

The show virtual-chassis command lists the member switches interconnected in a Virtual Chassis configuration with the member IDs that have been assigned by the master, the status of each member switch, the mastership priority values, and the roles. It also displays the neighbor members with which each member is interconnected. The output shows that all switches are in the desired Prsnt state and that switch-0 and switch-1 are in the master and backup roles.

Troubleshooting the Virtual Chassis

To troubleshoot the configuration of an EX2200 Virtual Chassis, perform these tasks:

Troubleshooting the Assignment of Roles

Problem

The master and backup roles are not assigned to the member switches that you want to function in these roles.

Solution

Modify the mastership priority values.

To quickly modify the mastership priority of any switch in the Virtual Chassis (in this case, member ID 1), enter the following command:

[edit virtual-chassis]

user@switch-0# set member 1 mastership-priority 255

Troubleshooting the VCPs

Problem

The VCPs are down.

Solution

  1. Check to make sure that you have cabled the appropriate ports.
  2. Check to make sure that the cables are seated properly.
  3. Check the output of the show virtual-chassis vc-port command to ensure you properly configured the VCPs. Enter the request virtual-chassis vc-port command to reconfigure the VCPs, if needed.