Supported Platforms
Example: Configuring an EX4500 Virtual Chassis with a Master and Backup in a Single Wiring Closet
A Virtual Chassis configuration is a scalable switch. You can provide secure, redundant network accessibility with a basic two-member EX4500 Virtual Chassis configuration and later expand the Virtual Chassis configuration to provide additional access ports as your office grows.
This example describes how to configure an EX4500 Virtual Chassis with a master and backup in a single wiring closet:
Requirements
This example uses the following hardware and software components:
- Junos OS Release 11.1 or later for EX Series switches
Note: You must use Junos OS Release 11.4 or later if you are including three or more EX4500 switches in an EX4500 Virtual Chassis or a mixed EX4200 and EX4500 Virtual Chassis.
- Two EX4500 switches with Virtual Chassis modules
Before you begin, be sure you have:
- Rack-mounted the switches. See Mounting an EX4500 Switch.
- Cabled the switches but not the Virtual Chassis ports (VCPs).
- Installed the same version of Junos OS Release 11.1 or later on both the switches
Overview and Topology
A Virtual Chassis configuration allows you to accommodate the networking needs of a growing office. The default configuration of a two-member Virtual Chassis includes a master and a backup switch. In addition to providing more access ports than a single switch can provide, a Virtual Chassis configuration provides high availability through redundancy.
After you interconnect the switches using the dedicated VCPs and power on the switches, the VCPs are operational. The mastership priorities and member IDs are assigned by the software. 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, see Understanding How the Master in an EX Series Virtual Chassis Is Elected. Therefore, we recommend that you start by powering on only one member switch, the one that you want to function as the master.
| Note: We recommend that you use the commit synchronize command to save any configuration changes that you make to a Virtual Chassis. |
The Virtual Chassis configuration provides networking access for onsite workers who are sitting within the range of a single wiring closet. The workers all use personal computers and VoIP phones. As the office grows, you can add EX4200 switches to meet increased needs for access ports.
The topology for this example consists of two EX4500 switches.
Table 1 shows the default configuration settings for the two-member Virtual Chassis.
Table 1: Components of the Basic Virtual Chassis Access Switch Topology
| Member Switch | Hardware | Member ID | Role and Priority |
|---|---|---|---|
SWA-0 | EX4500 switch | 0 | Master: mastership priority 128 |
SWA-1 | EX4500 switch | 1 | Backup: mastership priority 128 |
Figure 1 shows that switches SWA-0 and SWA-1 are interconnected with their dedicated VCPs on the rear panel. The LCD on the front displays the member ID and role.
Figure 1: Basic EX4500 Virtual Chassis with Master and Backup
Configuration
Configure a Virtual Chassis with a default master and backup in a single wiring closet:
Step-by-Step Procedure
To configure a Virtual Chassis with master and backup:
- Power on SWA-0 (the member switch that you want to function as the master).
- Power on SWA-1 (the member switch that you want to function as the backup).
- Set the PIC mode to Virtual Chassis mode on both switches:
user@switch> request chassis pic-mode virtual-chassis - Run the EZSetup program on SWA-0, specifying the identification parameters. See Connecting and Configuring an EX Series Switch (CLI Procedure) for details.
- Cable the Virtual Chassis member switches together.
- (Optional) Configure SWA-0 with the virtual management
Ethernet (VME) interface for out-of-band management of the Virtual
Chassis configuration, if desired:
[edit]
user@SWA-0# set interfaces vme unit 0 family inet address /ip-address/mask/ - (Optional, but recommended) Disable the split and merge
feature:
[edit virtual-chassis]
user@switch# set no-split-detection
Verification
To confirm that the Virtual Chassis configuration is operational, perform these tasks:
- Verifying That the Mastership Priority Is Assigned Appropriately
- Verifying That the VCPs Are Operational
Verifying That the Mastership Priority Is Assigned Appropriately
Purpose
Verify that the master, which has been selected by default, is the member switch that you want to function in that role.
Action
- Check the front-panel LCD to confirm that the switch has powered on correctly and that a member ID has been assigned.
- List the member switches of the Virtual Chassis configuration.
user@SWA-0> show virtual-chassisVirtual Chassis ID: 0019.e250.47a0
Mastership Neighbor List
Member ID Status Serial No Model priority Role ID Interface
0 (FPC 0) Prsnt AK0207360276 ex4500-40f 128 Master* 1 vcp-0
1 vcp-1
1 (FPC 1) Prsnt AK0207360281 ex4500-40f 128 Backup 0 vcp-0
0 vcp-1
Member ID for next new member: 2 (FPC 2)
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 mastership priority values, and the roles. It also displays the neighbor members with which each member is interconnected. The output shows that SWA-0, member 0, has been assigned default mastership priority 128. Because SWA-0 is the first member to be powered on, it has the most seniority and is therefore assigned the role of master. SWA-1 is powered on after member 0, so it is assigned the role of backup. The member IDs are displayed on the front panel of the switches. Check and confirm whether the default assignment is satisfactory.
Verifying That the VCPs Are Operational
Purpose
Verify that the dedicated VCPs interconnecting the switches are operational.
Action
Display the VCPs of all the members:
user@SWA-0> show virtual-chassis vc-port all-members
fpc0: -------------------------------------------------------------------------- Interface Type Status Speed Neighbor or (mbps) ID Interface PIC / Port vcp-0 Dedicated Up 32000 1 vcp-1 vcp-1 Dedicated Up 32000 1 vcp-0 fpc1: -------------------------------------------------------------------------- Interface Type Status Speed Neighbor or (mbps) ID Interface PIC / Port vcp-0 Dedicated Up 32000 1 vcp-1 vcp-1 Dedicated Up 32000 1 vcp-0
Meaning
The show virtual-chassis command lists the interfaces that are enabled for the member switches of the Virtual Chassis configuration and shows the status of the interfaces. The output in this example shows that two of the VCPs are operational. A single cable has been used to interconnect vcp-0 of member ID 0 and vcp-0 of member ID 1. That interconnection is sufficient for the switch to be operational. However, we recommend that you connect the second set of VCPs for redundancy.
Troubleshooting the Virtual Chassis
To troubleshoot the configuration of a 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 SWA-1 (member ID 1), copy the following command and paste it into the switch terminal window:
[edit virtual-chassis]
user@SWA-1# set member 1 mastership-priority 255 Troubleshooting the VCPs
Problem
The VCPs are down.
Solution
- Check to make sure that you have cabled the appropriate ports.
- Check to make sure that the cables are seated properly.
We recommend that you interconnect both of the VCPs on the member switches, for redundancy and high availability.
